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A study of the photorearrangements of crystalline dibenzobarrelene and cyclohexenone derivatives Chen, Jianxin 1991

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A STUDY OF THE PHOTOREARRANGEMENTS OF CRYSTALLINE DIBENZOBARRELENE AND CYCLOHEXENONE DERIVATIVES by Jianxin Chen B.Sc. Wuhan University, China, 1982 M.Sc, Academy, of Sciences of China, Beijing, 1985 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (DEPARTMENT OF CHEMISTRY) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA FEBRUARY 1991 © Jianxin Chen, 1991 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University of British Columbia Vancouver, Canada Department DE-6 (2/88) - i i -\ ABSTRACT Two s e r i e s o f compounds, 4 , 4 - d i a r y l c y c l o h e x e n o n e s and 9-s u b s t i t u t e d d i b e n z o b a r r e l e n e s , were s y n t h e s i z e d and t h e i r p h o t o c h e m i s t r y was i n v e s t i g a t e d i n t h e c r y s t a l l i n e s t a t e and i n s o l u t i o n medium. The d i f f e r e n c e s i n p h o t o r e a c t i v i t y and p r o d u c t s e l e c t i v i t y o f t h e s e compounds between the s o l u t i o n a n d s o l i d s t a t e s have been d e t e r m i n e d , and p o s s i b l e s t r u c t u r e - r e a c t i v i t y c o r r e l a t i o n s a r e d i s c u s s e d b a s e d on X -r a y c r y s t a l l o g r a p h i c d a t a f o r some o f the s u b s t a n c e s . The p h o t o r e a r r a n g e m e n t o f 4 , 4 - d i a r y l c y c l o h e x e n o n e s was found to be a f f e c t e d m o d e r a t e l y by the c r y s t a l l a t t i c e . The m i g r a t o r y a p t i t u d e o f the a r y l groups f o r 4 - p h e n y l - 4 - a r y l c y c l o h e x e n o n e s was shown to be c o n t r o l l e d to a l e s s e r e x t e n t b y the e l e c t r o n i c e f f e c t i n the s o l i d s t a t e compared to s o l u t i o n . I r r a d i a t i o n o f 4 , 4 - d i p h e n y l - 6 - m e t h y l -c y c l o h e x e n o n e i n the c r y s t a l l i n e phase gave the same p h o t o p r o d u c t s and a s i m i l a r p r o d u c t d i s t r i b u t i o n as t h a t i n the s o l u t i o n p h a s e . I n t h i s c a s e , c o n f o r m a t i o n a l a n a l y s i s r e v e a l s t h a t b o t h p s e u d o - a x i a l and pseudo-e q u a t o r i a l p h e n y l groups o f the enone m o i e t y a r e c a p a b l e o f m i g r a t i n g . The d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f a number o f 9 - s u b s t i t u t e d d i b e n z o b a r r e l e n e d e r i v a t i v e s gave two r e g i o i s o m e r i c d i b e n z o -s e m i b u l l v a l e n e p r o d u c t s upon p h o t o l y s i s i n s o l u t i o n and i n the s o l i d s t a t e . I n g e n e r a l , the e f f e c t o f the c r y s t a l l i n e e n v i r o n m e n t on the r e a c t i o n r e g i o s e l e c t i v i t y i s f o u n d t o be s m a l l . R e s o l v e d c h i r a l s u b s t i t u e n t s ( h a n d l e s ) a t the 9 - p o s i t i o n o f t h e d i b e n z o b a r r e l e n e m o i e t y were used t o f o r c e the compounds to c r y s t a l l i z e i n c h i r a l space g r o u p s . A s y m m e t r i c i n d u c t i o n s via p h o t o l y s i s o f the c h i r a l c r y s t a l s v a r i e d from - i l l -small to moderate depending on the nature of the c h i r a l substituent. It was found that, i n some cases, asymmetric induction i n the s o l i d state i s s i g n i f i c a n t l y higher than in s o l u t i o n , but i s lower i n one instance. In addition, the c h i r a l c r y s t a l l i n e environment has d i f f e r e n t e f f e c t s on the asymmetric inductions in a dual pathway di-w-methane rearrangement. The di-w-methane photorearrangement of 9,12-bridged dibenzobarrelene lactones was found to proceed very e f f i c i e n t l y i n s o l u t i o n and i n the s o l i d state. The unusual r e g i o s e l e c t i v i t y observed was r a t i o n a l i z e d i n terms of an intramolecular s t e r i c e f f e c t rather than an e l e c t r o n i c s t a b i l i z i n g e f f e c t . An absolute asymmetric synthesis with high o p t i c a l y i e l d was achieved by photolyses of c h i r a l c r y s t a l s of the a c h i r a l compound, methyl 3,5-dihydro-3-oxo-1H-5,9b[1',2']benzeno-naphtho[1,2-c]furan-4-carboxylate. Photochemical [2+2] cycloaddition of t h i s substrate to 1,3-dienes was found to be mechanistically i n t e r e s t i n g , involving an excited t r i p l e t state of 1,3-diene which i s formed by energy transfer. An unusual excited s i n g l e t state rearrangement of 9-chloromethyl substituted dibenzobarrelene d i e s t e r was discovered. X-ray c r y s t a l l o g r a p h i c analyses revealed that an intermolecular chlorine atom transfer i s involved i n the formation of unusual dibenzopentalene photoproducts. F i n a l l y , a novel s o l i d state photochromism was found, and a r a d i c a l species was proposed as the intermediate responsible for the observed photochromic phenomenon. - iv -To my parents and To my wife and daughter - V -TABLE OF CONTENTS TITLE PAGE i ABSTRACT i i DEDICATION i v TABLE OF CONTENTS v LIST OF TABLES x LIST OF FIGURES x i LIST OF SCHEMES x i v ACKNOWLEDGMENTS x v i i i INTRODUCTION 1 I. Photochemistry i n the S o l i d State 3 I I . The Topochemical P r i n c i p l e 7 I I I . R e a c t i v i t y and S e l e c t i v i t y of Organic Reactions i n the C r y s t a l l i n e State 10 IV. Asymmetric Syntheses v i a Photoreaction of C h i r a l Crystals 16 V. Unimolecular Photorearrangements 22 A. Photorearrangement of Cyclohexenone Systems 23 B. The Di-7r-Methane Rearrangement 26 VI. Objectives of Present Research 32 RESULTS AND DISCUSSION 37 I. Preparation of Sta r t i n g Materials 38 A. Synthesis of Cyclohexenone Substrates 38 - v i -B. Synthesis of 9-Substituted 9,10-Ethenoanthracene Substrates 40 C. Preparation of C r y s t a l l i n e Samples 47 I I . Studies on 4,4-Diarylcyclohexenones 48 A. Photorearrangement of 4-Phenyl-4-arylcyclohexenones 48 1. Photochemistry of 4-Phenyl-4-p-cyanophenyl-cyclohexenone (71b) and 4-Phenyl-4-p-bromophenylcyclohexenone (71a) 50 2. Migratory Aptitude i n the S o l i d State 55 3. Molecular Cr y s t a l Structure of 4-Phenyl-4-p-bromophenylcyclohexenone (71a) and Its Photochemical Implications 59 B. Photorearrangement of 4,4-Diphenyl-6-alkylcyclohexenones 63 1. Photochemistry 63 2. Product Ratio Studies on Enone 74a i n Solution and i n the S o l i d State 67 I I I . Studies on the Di-*-Methane Photorearrangement of 9-Substituted Dibenzobarrelene Diesters 75 A. Photochemistry of 9-Formyl, 9-Hydroxymethyl and 9-Acetoxymethyl 9,10-Ethenoanthracene-ll,12-dicarboxylates (94, 95 and 93c) 77 B. S o l i d State Results 81 1. R e g i o s e l e c t i v i t y i n the S o l i d State vs Solution 81 - v i i -2. Molecular C r y s t a l Structure of 9-Formyl 9,10-Ethenoanthracene Diester 94 84 IV. Asymmetric Induction v i a Photoreactions of C h i r a l C r y s t a l s 89 A. Studies on 9-Substituted Dibenzobarrelene V i n y l Monoesters 89 1. Photochemistry of 9-Substituted Dibenzo-barrelene V i n y l Monoesters 99 and 100 92 2. Results on D i a s t e r e o s e l e c t i v i t y i n the S o l i d State vs Solution 95 B. Studies on 9,10-Ethenoanthracene Diesters with Resolved C h i r a l Handles at the 9-Position 97 1. Photochemistry 97 2. Results on the Regio- and D i a s t e r e o s e l e c t i v i t i e s 98 3. Molecular C r y s t a l Structure of Compound 93b and Its Photochemical Implications 102 V. Studies on the Photoreactivity and S e l e c t i v i t y of Dibenzobarrelene Lactones 108 A. Photochemical Studies on Dibenzobarrelene Lactone-Ester 96 108 1. Photochemistry of Lactone-Ester 96 108 2. Interpretation on the Reaction R e g i o s e l e c t i v i t y of 96 i n Solution I l l 3. Absolute Asymmetric Synthesis v i a Photoreaction of C h i r a l Crystals of Lactone-Ester 96 118 - v i i i -4. Mechanistic Interpretation of the S o l i d State Asymmetric Induction from Lactone-Ester 96 125 B. Photochemistry of Methyl Lactone-Ester 97 127 1. Photolysis of Methyl Lactone-Ester 97 i n Solution 128 2. S o l i d State Results 132 C. E l e c t r o n i c versus S t e r i c E f f e c t i n the Photorearrangement of Lactone 98 137 D. Studies on the Photoreactivity of 9,10-Etheno-anthracene Lactones 96, 97, 98 and 93c 140 1. Quantum Y i e l d ($) Measurements 140 2. Quenching Results on the Lactone-Ester 96 and Diester 93c 144 E . Photocycloadditions of Lactone-ester 96 to 1,3-Dienes 148 1. Cycloaddition of Lactone-ester 96 to 2,5-Dimethyl-2,4-hexadiene 150 2. Cycloaddition of Lactone-Ester 96 to 1,3-Cyclohexadiene 155 3. Mechanistic Studies on the Photocycloaddition of Lactone-Ester 96 to 1,3-Dienes 167 VI. Studies on 9-Chloromethyl 9,10-Ethenoanthracene Diester 93d 170 A. Unusual Photorearrangement of 9-Chloromethyl Dibenzobarrelene Diester 93d 173 1. Photolysis i n Solution and i n the S o l i d State 173 - ix -2. Product Ratio Analysis 175 3. A Possible Mechanism for the Formation of exo-Methylene Dibenzopentalenes 196 and 197 177 B. S o l i d State Photochromism of 9-Chloromethyl Dibenzobarrelene 93d 185 1. General Observations on the Photochromism of Compound 93d 187 2. Speculation on the Nature of the Colored Species 189 EXPERIMENTAL 194 I. General 195 II . Synthesis of Substrates 199 A. Cyclohexenone Derivatives 199 B. Dibenzobarrelene Derivatives 206 I I I . Photochemical Studies 228 A. General Procedures 228 B. Photochemistry of Substrates 229 1. Cyclohexenone Derivatives 229 2. Dibenzobarrelene Derivatives 240 C. Quantum Y i e l d s and Quenching Studies 268 REFERENCES 272 LIST OF TABLES Table 1 Summary of Cr y s t a l Preparations 47 Table 2 Photolysis of 4-Phenyl-4-p-cyanophenyl-cyclohexenone at D i f f e r e n t I r r a d i a t i o n Wavelengths 52 Table 3 Photolysis of 4-Phenyl-4-p-bromophenyl-cyclohexenone (71a) i n Benzene under Varying Conversions 54 Table 4 Migratory S e l e c t i v i t y of 4-p-Cyanophenyl- and 4-p-Bromophenyl-4-phenylcyclohexenones i n Solution and i n the S o l i d State 57 Table 5 Photoproduct Ratios of Endo:Exo (75a:76a) from Photorearrangement of 74a i n Various Solvents 68 Table 6 Product Ratios from Photolysis of Enone 74a i n the S o l i d State 70 Table 7 Product Ratios i n Photorearrangement of 9-Substituted 9 ,10-Ethenoanthracenes 82 Table 8 Summary on the Reaction D i a s t e r e o s e l e c t i v i t y of 99 96 Table 9 Regio- and D i a s t e r e o s e l e c t i v i t y i n the S o l i d State and Solution 99 Table 10 Asymmetric Inductions i n rhe S o l i d State Photoreaction of Lactone-Ester 96 121 Table 11 Product D i s t r i b u t i o n s i n the Solution and the S o l i d State I r r a d i a t i o n s of Lactones 96 and 97 136 Table 12 Quantum Yiel d s ($) of Product Formation from Photolysis of Dibenzobarrelenes 96, 97, 98 and 93c 141 Table 13 Quantum Yields and T r i p l e t Lifetimes of Some 9 ,10-Ethenoanthracenes 143 * Table 14 Product Ratios from Photolysis of 9-Chloromethyl Dibenzobarrelene 93d i n D i f f e r e n t Media 176 - x i -L I S T O F F I G U R E S F i g u r e 1 C o m p o s i t e D i a g r a m C o m p a r i n g t h e P a c k i n g o f t h e M o l e c u l a r U n i t s w i t h i n t h e M o n o m e r a n d D i m e r C r y s t a l S t r u c t u r e s o f B e n z y l i d e n e -c y c l o p e n t a n o n e 11 F i g u r e 2 P i c t o r i a l R e p r e s e n t a t i o n o f " R e a c t i o n C a v i t y " C o n c e p t 12 F i g u r e 3 P a r t i a l NMR S p e c t r a o f D i b e n z o b a r r e l e n e s 99 a n d 100 46 F i g u r e 4 S t e r e o d i a g r a m o f t h e M o l e c u l e o f trans-5-P h e n y l - 6 - p - b r o m o p h e n y l b i c y c l o [ 3 . 1 . 0 ] h e x a n - 2 -o n e ( 7 2 a ) 53 F i g u r e 5 S t e r e o d i a g r a m o f C y c l o h e x e n o n e 7 1 a w i t h D i s o r d e r 59 F i g u r e 6 C r y s t a l P a c k i n g D i a g r a m o f C y c l o h e x e n o n e 7 1 a 60 F i g u r e 7 P a r t i a l NMR S p e c t r a o f exo-trans- a n d endo-trans-5,6-Diphenyl-3-methylbicyclo-[ 3 . 1 . 0 ] h e x a n o n e s 65 F i g u r e 8 O R T E P D r a w i n g s o f M o l e c u l a r M e c h a n i c s M i n i m i z e d H a l f - M i g r a t e d T r i p l e t B i r a d i c a l s 68 F i g u r e 9 S t e r e o d i a g r a m o f t h e M o l e c u l e D i m e t h y l 9 -F o r m y l - 9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o a n t h r a c e n e -1 1 , 1 2 - d i c a r b o x y l a t e ( 9 4 ) 85 F i g u r e 10 C r y s t a l P a c k i n g D i a g r a m o f D i m e t h y l 9 - F o r m y l -9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o a n t h r a c e n e - 1 1 , 1 2 -d i c a r b o x y l a t e ( 9 4 ) 86 F i g u r e 11 P a r t i a l ^H NMR S p e c t r u m o f P h o t o p r o d u c t 1 4 5 94 F i g u r e 12 P a r t i a l ^H NMR S p e c t r u m o f R e a c t i o n M i x t u r e f r o m 9 3 b 100 F i g u r e 13 P a r t i a l "^H NMR S p e c t r u m o f R e a c t i o n M i x t u r e f r o m 9 3 a 101 F i g u r e 14 M o l e c u l a r C r y s t a l S t r u c t u r e a n d P a c k i n g D i a g r a m s o f C o m p o u n d 9 3 b 103 F i g u r e 15 S t e r i c E f f e c t i n t h e P h o t o r e a r r a n g e m e n t o f 9 -S u b s t i t u t e d D i b e n z o b a r r e l e n e D i e s t e r 9 3 b v i a P a t h B M e c h a n i s m 107 - x i i -F i g u r e 16 M o l e c u l a r S t r u c t u r e o f L a c t o n e - E s t e r 96 S h o w i n g H - - - H C o n t a c t s 116 F i g u r e 17 P a r t i a l ^ NMR S p e c t r a o f L a c t o n e - E s t e r 96 117 F i g u r e 18 S t e r e o d i a g r a m o f C o m p o u n d 96 118 F i g u r e 19 P a r t i a l NMR S p e c t r a o f t h e P h o t o l y s a t e o f c o m p o u n d 96 i n t h e S o l i d S t a t e . 122 F i g u r e 20 C r y s t a l P a c k i n g D i a g r a m o f L a c t o n e - E s t e r 96 127 F i g u r e 21 P a r t i a l * H NMR S p e c t r a o f P h o t o p r o d u c t 168 1 3 0 F i g u r e 22 P a r t i a l 1 H NMR S p e c t r a o f P h o t o p r o d u c t 1 7 0 131 F i g u r e 23 S t e r e o d i a g r a m o f P h o t o p r o d u c t 1 7 1 135 F i g u r e 24 A S t e r n - V o l m e r P l o t f o r t h e F o r m a t i o n o f D i b e n z o s e m i b u l l v a l e n e L a c t o n e 1 5 3 f r o m L a c t o n e - E s t e r 96 i n t h e P r e s e n c e o f 2,5-D i m e t h y l - 2 , 4 - h e x a d i e n e 146 F i g u r e 25 A S t e r n - V o l m e r P l o t f o r F o r m a t i o n o f D i b e n z o s e m i b u l l v a l e n e s 1 2 0 . a n d 1 2 4 f r o m 9 3 c i n t h e P r e s e n c e o f 1 , 3 - C y c l o h e x a d i e n e 147 F i g u r e 26 P a r t i a l Hi NMR S p e c t r a o f P h o t o a d d u c t 1 8 5 . . / 152 F i g u r e 27 S t r u c t u r a l I n f o r m a t i o n o f P h o t o a d d u c t s 1 8 5 a n d 186 . . . . . ..... 153 F i g u r e 28 P a r t i a l 1H NMR S p e c t r a o f P h o t o a d d u c t 1 8 6 154 F i g u r e 29 S t r u c t u r a l A s s i g n m e n t o f t h e [2+2] A d d u c t s 1 8 7 a n d 188 157 F i g u r e 30 P a r t i a l Hi NMR S p e c t r a o f P h o t o p r o d u c t 1 8 7 158 F i g u r e 31 P a r t i a l 2D C O S Y X H NMR S p e c t r u m o f P h o t o p r o d u c t 187 159 F i g u r e 32 P a r t i a l 1 H NMR S p e c t r a o f P h o t o p r o d u c t 1 8 7 160 F i g u r e 33 P a r t i a l * H NMR S p e c t r a o f P h o t o p r o d u c t 1 8 8 162 F i g u r e 34 P a r t i a l 1 H NMR S p e c t r a o f P h o t o p r o d u c t 1 8 8 163 F i g u r e 35 P a r t i a l NMR S p e c t r a o f P h o t o p r o d u c t 1 8 9 165 F i g u r e 36 S t r u c t u r e s o f P h o t o p r o d u c t 189 a n d I t s I s o m e r 191 166 F i g u r e 37 P a r t i a l 1H NMR S p e c t r a o f P h o t o p r o d u c t 1 8 9 166 - x i i i -F i g u r e 38 F T I R S p e c t r a o f C r y s t a l l i n e 9 - C h l o r o m e t h y l D i b e n z o b a r r e l e n e 9 3 d 171 F i g u r e 39 O R T E P D r a w i n g o f t h e M o l e c u l a r S t r u c t u r e o f P h o t o p r o d u c t 196 174 F i g u r e 4 0 O R T E P D r a w i n g o f t h e M o l e c u l a r S t r u c t u r e o f P h o t o p r o d u c t 197 1 7 5 F i g u r e 4 1 C r y s t a l P a c k i n g D i a g r a m o f C o m p o u n d 93d (/9-f o r m ) 184 F i g u r e 4 2 I n t e r m o l e c u l a r C o n t a c t i n C r y s t a l S t r u c t u r e o f 220 187 F i g u r e 4 3 U V - V T S A b s o r p t i o n S p e c t r u m o f t h e B l u e - P u r p l e S p e c i e s F o r m e d i n t h e P h o t o c h r o m i c / ? - T y p e C r y s t a l s o f 9 3 d 188 F i g u r e 4 5 E S R S p e c t r a o f t h e B l u e - P u r p l e S p e c i e s F o r m e d i n t h e P h o t o c h r o m i c p " - T y p e C r y s t a l s o f C o m p o u n d 9 3 d 191 F i g u r e 46 S t r u c t u r e s o f O t h e r P h o t o c h r o m i c D i b e n z o b a r r e l e n e C o m p o u n d s , 192 - xiv -LIST OF SCHEMES S c h e m e 1 E x a m p l e s o f P h o t o r e a c t i o n s i n S o l u t i o n v e r s u s t h e S o l i d S t a t e 4 S c h e m e 2 P h o t o c h e m i c a l [2+2] C y c l o a d d i t i o n s o f trans-C i n n a m i c A c i d i n t h e C r y s t a l l i n e S t a t e 8 S c h e m e 3 P h o t o d i m e r i z a t i o n o f B e n z y l i d e n e c y c l o -p e n t a n o n e 10 S c h e m e 4 R e a c t i o n C o n t r o l l e d b y " S t e r i c C o m p r e s s i o n " 13 S c h e m e 5 A b s o l u t e A s y m m e t r i c S y n t h e s i s b y S o l i d S t a t e [2+2] P h o t o c y c l o a d d i t i o n 19 S c h e m e 6 A b s o l u t e A s y m m e t r i c S y n t h e s e s v i a N o r r i s h T y p e I I a n d D i - f f - M e t h a n e R e a c t i o n s i n t h e S o l i d S t a t e 20 S c h e m e 7 A b s o l u t e A s y m m e t r i c S y n t h e s i s o f ^ - L a c t a m 29 21 S c h e m e 8 P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i m e t h y l - 2 -c y c l o h e x e n - l - o n e 24 J S c h e m e 9 P h o t o t r a n s f o r m a t i o n s o f 4 - P h e n y l - 4 - m e t h y l - 2 -c y c l o h e x e n - l - o n e a n d 4 , 4 - D i p h e n y l - 2 -c y c l o h e x e n - l - o n e 25 S c h e m e 10 R e p r e s e n t a t i o n o f a S i m p l e D i - 7 r - M e t h a n e R e a r r a n g e m e n t 27 S c h e m e 11 E x a m p l e s o f t h e D i - « - M e t h a n e P h o t o r e a r r a n g e m e n t 28 S c h e m e 12 P h o t o r e a r r a n g e m e n t o f t h e B a r r e l e n e S y s t e m s : . . . 29 S c h e m e 13 P h o t o c h e m i c a l T r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e D i e s t e r D e r i v a t i v e 30 S c h e m e 14 T h e D i - w - M e t h a n e P h o t o r e a r r a n g e m e n t o f 9 - M e t h y l D i b e n z o b a r r e l e n e D i e s t e r 31 S c h e m e 15 P h o t o r e a r r a n g e m e n t o f 4 - A r y l - 4 -p h e n y l c y c l o h e x e n o n e s 33 S c h e m e 16 P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i p h e n y l - 6 -a l k y l c y c l o h e x e n o n e s 34 S c h e m e 17 P h o t o r e a r r a n g e m e n t o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e s 35 - XV -S c h e m e 18 S y n t h e s e s o f 4 - p - B r o m o p h e n y l - a n d 4 - p -C y a n o p h e n y l - 4 - p h e n y l - c y c l o h e x e n o n e s 38 S c h e m e 19 S y n t h e s i s o f 4 , 4 - D i p h e n y l - 6 - m e t h y l c y c l o -h e x e n o n e ( 7 4 a ) a n d 4 , 4 - D i p h e n y l - 6 -e t h y l c y c l o h e x e n o n e ( 7 4 b ) 39 S c h e m e 20 P r e p a r a t i o n o f 9 - S u b s t i t u t e d A n t h r a c e n e s 4 1 S c h e m e 21 P r e p a r a t i o n o f B r i d g e h e a d S u b s t i t u t e d D i b e n z o b a r r e l e n e C o m p o u n d s v i a D i e l s - A l d e r R e a c t i o n 4 2 S c h e m e 22 P r e p a r a t i o n o f L a c t o n e - E s t e r 96 a n d M e t h y l L a c t o n e - E s t e r 97 43 S c h e m e 23 E s t e r i f i c a t i o n s b e t w e e n A l c o h o l 95 a n d t h e C o r r e s p o n d i n g A c i d C h l o r i d e s 44 S c h e m e 24 S y n t h e s i s o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e M o n o e s t e r s 45 S c h e m e 25 P h o t o t r a n s f o r m a t i o n s o f 4 , 4 - D i a r y l -c y c l o h e x e n o n e s 49 S c h e m e 26 P h o t o r e a r r a n g e m e n t o f 4 - P h e n y l - 4 -a r y l c y c l o h e x e n o n e s 50 S c h e m e 27 C o n v e r s i o n o f P h o t o p r o d u c t s 7 2 a a n d 7 3 a t o t h e K n o w n C y a n o D e r i v a t i v e s 7 2 b a n d 7 3 b 53 S c h e m e 28 M e c h a n i s t i c P r e s e n t a t i o n o f t h e P h o t o r e a r r a n g e m e n t o f 4 - P h e n y l - 4 -a r y l c y c l o h e x e n o n e s 55 S c h e m e 29 O r b i t a l O v e r l a p A r r a n g e m e n t i n 1 , 2 - S h i f t o f P h e n y l G r o u p 62 S c h e m e 30 S t e r i c H i n d r a n c e o n t h e R o t a t i o n o f t h e p - B r o m o p h e n y l G r o u p i n t h e B u l k C r y s t a l s 62 S c h e m e 31 P h o t o c h e m i s t r y o f 4 , 4 - D i p h e n y l - 6 - a l k y l -c y c l o h e x e n o n e s 64 S c h e m e 32 S y n t h e s e s o f P h o t o p r o d u c t s 7 6 a a n d 7 6 b a n d E p i m e r i z a t i o n o f P h o t o p r o d u c t 7 5 a 66 S c h e m e 33 M e c h a n i s m o f P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i p h e n y l c y c l o h e x e n o n e s 71 S c h e m e 34 C o n f o r m a t i o n a l E q u i l i b r i u m o f 6 - M e t h y l C y c l o h e x e n o n e 7 4 a 72 - x v i -S c h e m e 35 Two P a t h w a y s o f P h o t o r e a r r a n g e m e n t o f C y c l o h e x e n o n e 7 4 a 74 S c h e m e 36 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e D i e s t e r s t o D i b e n z o s e m i b u l l v a l e n e s 76 S c h e m e 37 P h o t o t r a n s f o r m a t i o n o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e s 79 S c h e m e 3 8 S y n t h e s i s o f P h o t o p r o d u c t 1 1 9 by a S e l e c t i v e R e d u c t i o n 81 S c h e m e 39 E l e c t r o n i c E f f e c t o n V a l e n c e T a u t o m e r i z a t i o n o f C y c l o h e p t a t r i e n e a n d N o r c a r a d i e n e 84 S c h e m e 4 0 P h o t o t r a n s f o r m a t i o n o f U n s y m m e t r i c a l D i b e n z o b a r r e l e n e D i e s t e r s 88 S c h e m e 41 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e 1 1 - E s t e r 90 S c h e m e 42 P h o t o t r a n s f o r m a t i o n o f M e t h y l 9,10 - D i h y d r o -9 , 1 0 - E t h e n o a n t h r a c e n e - 9 - c a r b o x y l a t e 91 S c h e m e 43 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e 9,11-D i e s t e r s 92 S c h e m e 44 P h o t o l y s i s o f 9 , 1 1 - D i s u b s t i t u t e d D i b e n z o b a r r e l e n e 99 93 S c h e m e 45 P h o t o t r a n s f o r m a t i o n o f 9 , 1 2 - D i s u b s t i t u t e d D i b e n z o b a r r e l e n e 1 0 0 95 S c h e m e 46 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e D i e s t e r s w i t h 9 - R e s o l v e d C h i r a l H a n d l e s 97 S c h e m e 47 D i - w - M e t h a n e P h o t o r e a r r a n g e m e n t o f A c i d - E s t e r 1 4 9 106 S c h e m e 48 P h o t o c h e m i c a l T r a n s f o r m a t i o n s o f L a c t o n e -E s t e r 96 a n d I t s A n a l o g u e 9 3 c 109 S c h e m e 49 I n d e p e n d e n t P r e p a r a t i o n o f P h o t o p r o d u c t s 1 5 2 a n d 153 I l l S c h e m e 50 P h o t o r e a r r a n g e m e n t s o f D i b e n z o b a r r e l e n e L a c t a m 154 113 S c h e m e 51 D i - i r - m e t h a n e P h o t o r e a r r a n g e m e n t o f D i b e n z o b a r r e l e n e A m i n e D e r i v a t i v e 1 6 0 114 S c h e m e 52 B i r a d i c a l I n t e r m e d i a t e s i n P h o t o r e a r r a n g e m e n t o f L a c t o n e - E s t e r 96 115 - x v i i -S c h e m e 53 P h o t o t r a n s f o r m a t i o n o f M e t h y l L a c t o n e - E s t e r 97 i n S o l u t i o n 128 S c h e m e 54 P h o t o r e a r r a n g e m e n t o f M e t h y l L a c t o n e - E s t e r 97 i n t h e S o l i d S t a t e 1 3 3 S c h e m e 55 I n d e p e n d e n t S y n t h e s e s o f P h o t o p r o d u c t 1 7 1 a n d I t s I s o m e r 172 1 3 5 S c h e m e 56 D i - w - M e t h a n e P h o t o r e a r r a n g e m e n t o f L a c t o n e 98 1 3 8 S c h e m e 57 Q u a n t u m Y i e l d a n d R e a c t i o n R a t e R e l a t i o n s h i p s 1 4 3 S c h e m e 58 G e n e r a l T r i p l e t Q u e n c h i n g M e c h a n i s m 1 4 6 S c h e m e 59 P h o t o c y c l o a d d i t i o n s o f 1 , 3 - D i e n e s 1 5 0 S c h e m e 60 [2+2] P h o t o c y c l o a d d i t i o n o f L a c t o n e - E s t e r 96 t o 2 , 5 - D i m e t h y l - 2 , 4 - h e x a d i e n e 1 5 1 S c h e m e 61 P h o t o c y c l o a d d i t i o n o f L a c t o n e - E s t e r 96 t o 1 , 3 - C y c l o h e x a d i e n e 1 5 5 S c h e m e 62 [4+2] P h o t o c y c l o a d d i t i o n o f 9 - A n t h r y l m e t h y l M e t h y l F u m a r a t e 167 S c h e m e 63 P h o t o l y s i s o f L a c t o n e - E s t e r 96 i n t h e P r e s e n c e o f 2 , 3 - D i m e t h y l - 2 - b u t e n e 169 S c h e m e 64 P h o t o r e a r r a n g e m e n t s o f 9 - C h l o r o m e t h y l D i b e n z o b a r r e l e n e 9 3 d 173 S c h e m e 65 P h o t o r e a r r a n g e m e n t o f D i b e n z o b a r r e l e n e v i a I t s S i n g l e t E x c i t e d S t a t e 178 S c h e m e 66 P h o t o r e a r r a n g e m e n t o f L a b e l e d B e n z o b a r r e l e n e v i a Si 179 S c h e m e 67 P h o t o r e a r r a n g e m e n t s o f 9 , 1 0 - D i m e t h y l D i b e n z o b a r r e l e n e D i e s t e r 2 0 4 1 8 0 S c h e m e 68 P h o t o r e a r r a n g e m e n t o f D i b e n z o y l D i b e n z o b a r r e l e n e 211 181 S c h e m e 69 P r o p o s e d M e c h a n i s m f o r t h e F o r m a t i o n o f P r o d u c t 196 a n d 197 182 S c h e m e 70 P h o t o t r a n s f o r m a t i o n o f T e t r a c h l o r o c y c l o -h e x a d i e n o n e 2 1 8 . 184 S c h e m e 71 P h o t o c h r o m i s m o f T e t r a c h l o r o d i h y d r o -n a p h t h a l e n - l - o n e ( 2 2 0 ) 186 - x v i i i -ACKNOWLEDGMENTS I w i s h t o e x p r e s s my d e e p e s t g r a t i t u d e t o my s u p e r v i s o r , D r . J o h n R . S c h e f f e r , f o r h i s e n c o u r a g e m e n t , s u p p o r t a n d g u i d a n c e , a n d f o r h i s f r i e n d s h i p a n d e n t h u s i a s m t h r o u g h o u t t h e p r o g r a m . I am g r e a t l y i n d e b t e d t o h i m f o r h i s m a n y i n v a l u a b l e i d e a s a n d c o n s t r u c t i v e s u g g e s t i o n s t h a t I n o t o n l y h a v e b e n e f i t t e d f r o m b u t a l s o w i l l b e n e f i t f o r y e a r s t o c o m e . I w o u l d a l s o l i k e t o t h a n k D r . J a m e s T r o t t e r a n d t h e m e m b e r s o f h i s r e s e a r c h g r o u p f o r t h e i r c o n t i n u o u s a s s i s t a n c e t h r o u g h t h e y e a r s . I am s p e c i a l l y g r a t e f u l t o D r . P h a n i R a j P o k k u l u r i who p e r f o r m e d m o s t o f t h e c r y s t a l l o g r a p h i c w o r k . I n a d d i t i o n , t h a n k s a r e d u e t o a l l t h e c o -w o r k e r s i n t h e g r o u p o f s o l i d s t a t e c h e m i s t r y a n d my f r i e n d s a t t h e C h e m i s t r y D e p a r t m e n t o f U B C . I t w a s a g r e a t p l e a s u r e t o s t u d y a n d t o c o l l a b o r a t e w i t h t h e s e p e o p l e i n s u c h a f r i e n d l y e n v i r o n m e n t . S p e c i a l t h a n k s a r e d u e t o M r . A l i s t a i r G . M. R a t t r a y a n d M r . M e l v i n Y a p f o r p r o o f r e a d i n g o f t h i s t h e s i s . I g r e a t l y a p p r e c i a t e t h e h e l p a n d t h e k i n d l y a s s i s t a n c e f r o m t h e s t a f f o f t h e d e p a r t m e n t a l NMR, MS a n d e l e m e n t a l a n a l y s i s l a b o r a t o r i e s . F i n a n c i a l s u p p o r t f r o m t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a a n d t h e A c a d e m y o f S c i e n c e s o f C h i n a i n t h e f o r m o f G r a d u a t e F e l l o w s h i p s i s g r a t e f u l l y a c k n o w l e d g e d . - 1 -INTRODUCTION 2 D u r i n g the p a s t two d e c a d e s , t h e r e has been a tremendous growth o f r e s e a r c h on o r g a n i c c h e m i c a l r e a c t i o n s i n a n i s o t r o p i c o r o r g a n i z e d m e d i a s u c h as c r y s t a l l i n e s o l i d s , l i q u i d c r y s t a l s , m i c e l l e s , m o n o l a y e r s , z e o l i t e s , h o s t - g u e s t c o m p l e x e s , p o l y m e r m a t r i c e s and s u r f a c e s . The u n d e r s t a n d i n g o f s t r u c t u r e - r e a c t i v i t y r e l a t i o n s h i p s and t h e mechanisms o f c h e m i c a l p r o c e s s e s has become w i d e r , as more c h e m i c a l r e a c t i o n s were e x p l o r e d i n t h e s e o r g a n i z e d m e d i a . I t has been a p r i m e g o a l o f o r g a n i c c h e m i s t s to a c h i e v e r e a c t i o n w i t h h i g h r e g i o - and s t e r e o s e l e c t i v i t y by d e s i g n i n g r e a c t i o n sy s t ems t h a t a r e s i m i l a r to t h o s e o f e n z y m a t i c p r o c e s s e s . An o u t s t a n d i n g f e a t u r e o f the e n z y m a t i c r e a c t i o n s i s the h i g h degree o f o r d e r i n t h e s y s t e m and the s t r i c t c o n t r o l o f m o l e c u l a r movement a l o n g the r e a c t i o n c o o r d i n a t e ( f r o m r e a c t a n t to p r o d u c t ) . By u s i n g a w e l l o r g a n i z e d s y s t e m i n w h i c h a c h e m i c a l r e a c t i o n p r o c e e d s , one might be a b l e to mimic the enzyme p r o c e s s and c o n t r o l the d i r e c t i o n o f r e a c t i o n i n the sense o f a c h i e v i n g h i g h s e l e c t i v i t y . C r y s t a l l i n e phase i s u n i q u e ; i t p o s s e s s e s the h i g h e s t d e g r e e o f o r d e r among the o r g a n i z e d m e d i a . T h e r e f o r e , i t seems a t t r a c t i v e to s t u d y c h e m i c a l r e a c t i o n s i n the c r y s t a l l i n e s o l i d . T h e r e a r e two i m p o r t a n t f a c t o r s t h a t g o v e r n a c h e m i c a l r e a c t i o n t a k i n g p l a c e i n the c r y s t a l l i n e p h a s e : the c o n f o r m a t i o n and the p a c k i n g arrangement o f the r e a c t i n g m o l e c u l e s . Compared to i s o t r o p i c ( l i q u i d ) phases i n w h i c h a f l e x i b l e o r g a n i c m o l e c u l e may a d o p t many c o n f o r m a t i o n s owing to the f a s t e q u i l i b r i a between them, i n the c r y s t a l the m o l e c u l e w i l l r a r e l y a d o p t more t h a n one c o n f o r m a t i o n , and i t i s o f t e n found t h a t o r g a n i c m o l e c u l e s c r y s t a l l i z e i n o r near t h e i r minimum e n e r g y c o n f o r m a t i o n s . ' ' ' C o n s i d e r i n g - 3 -t h a t t h e o u t c o m e o f t h e r e a c t i o n i s s e n s i t i v e t o t h e c o n f o r m a t i o n , o n e may e x p e c t t h a t t h e r e a c t i o n i n t h e c r y s t a l l i n e p h a s e w o u l d b e m o r e s e l e c t i v e t h a n t h a t i n s o l u t i o n . T h e p a c k i n g p a t t e r n o f t h e r e a c t i n g m o l e c u l e s i n t h e c r y s t a l i s a l s o c r u c i a l . T h a t i s , t h e n e i g h b o r i n g m o l e c u l e s ( t h e m e d i u m o r t h e e n v i r o n m e n t ) a r o u n d t h e r e a c t a n t i n t h e c r y s t a l may h a v e s u c h a p r o f o u n d e f f e c t o n t h e r e a c t i o n c o u r s e t h a t t h e c h e m i c a l c o n s e q u e n c e s w o u l d b e c o n t r o l l e d b y t h e m o l e c u l a r p a c k i n g a r r a n g e m e n t . I. P h o t o c h e m i s t r y i n t h e S o l i d S t a t e A l t h o u g h i n v e s t i g a t i o n s o f o r g a n i c p h o t o r e a c t i o n s i n t h e s o l i d s t a t e d a t e b a c k t o t h e e n d o f t h e l a s t c e n t u r y , t h e y h a v e b e e n s t u / i i e d w i d e l y o n l y i n r e c e n t y e a r s . Now, t h e i n v o l v e m e n t o f X - r a y c r y s t a l l o g r a p h y a n d o t h e r s o l i d s t a t e s p e c t r o s c o p i c t e c h n i q u e s s u c h a s 13 m a g i c a n g l e s p i n n i n g s o l i d s t a t e C NMR h a v e p r o v e d t o b e i n v a l u a b l e f o r s t r u c t u r e - r e a c t i v i t y c o r r e l a t i o n s . T h i s i s b e c a u s e t h e y p r o v i d e a d e t a i l e d p i c t u r e o n t h e m o l e c u l a r s t r u c t u r e a n d t h e p a c k i n g a r r a n g e m e n t o f r e a c t a n t ( a n d p r o d u c t ) . A n u m b e r o f r e v i e w a r t i c l e s o n s o l i d s t a t e p h o t o c h e m i s t r y h a s 3 a p p e a r e d i n r e c e n t y e a r s , a n d many e x a m p l e s o f s o l i d s t a t e r e a c t i o n s h a v e b e e n r e p o r t e d . S c h e m e 1 s h o w s some t y p i c a l e x a m p l e s t a k e n f r o m t h e l i t e r a t u r e , w h i c h d e m o n s t r a t e c o m p l e t e l y d i f f e r e n t p h o t o c h e m i c a l b e h a v i o r o f o r g a n i c m o l e c u l e s i n s o l u t i o n v e r s u s t h e s o l i d s t a t e . - 4 -Only Product R o t | 0 1 : 2 - 1 ( R e f . 5 ) 7 5 6 Oimers Me Me ( R e f . 6 ) 10 8 9 S c h e m e 1 E x a m p l e s o f P h o t o r e a c t i o n s i n S o l u t i o n v e r s u s t h e S o l i d S t a t e . - 5 -Q u i n k e r t a n d c o - w o r k e r s i n v e s t i g a t e d t h e p h o t o r e a c t i o n o f 1 , 1 , 3 -t r i p h e n y l - 2 - p r o p a n o n e ( 1 ) i n t h e s o l i d s t a t e v e r s u s s o l u t i o n . T h e y f o u n d t h a t , i n s o l u t i o n , p h o t o l y s i s o f t h i s c o m p o u n d l e d t o t h e l o s s o f c a r b o n m o n o x i d e a n d t h e f o r m a t i o n o f t h r e e r a d i c a l c o u p l i n g p r o d u c t s 2 , 3 a n d 4 i n a s t a t i s t i c a l r a t i o o f 1 : 2 : 1 . H o w e v e r , i r r a d i a t i o n o f c r y s t a l s o f 1 r e s u l t e d i n t h e e x c l u s i v e p r o d u c t o f 1 , 1 , 2 - t r i p h e n y l e t h a n e ( 3 ) . I n t h e s a m e p a p e r , t h e y a l s o r e p o r t e d s t e r e o s p e c i f i c p h o t o e x t r u s i o n r e a c t i o n s o f 1 , 3 - d i p h e n y l - 2 - i n d a n o n e s i n t h e s o l i d s t a t e c o m p a r e d t o t h e s a m e r e a c t i o n s i n s o l u t i o n i n w h i c h t h e s t e r e o c h e m i s t r y o f t h e p r o d u c t was g o v e r n e d b y t h e r m o d y n a m i c f a c t o r s . O n e o f t h e e a r l i e s t i n v e s t i g a t i o n s o f t h e e f f e c t o f t h e c r y s t a l l i n e e n v i r o n m e n t o n u n i m o l e c u l a r p h o t o r e a c t i v i t y w a s t h a t o f M a t s u u r a et al o n s a n t o n i n 5 s h o w n i n t h e m i d d l e o f S c h e m e 1 . D i e n o n e 5 r e a r r a n g e s t o l u m i s a n t o n i n 6 u p o n p h o t o l y s i s i n b e n z e n e . O n t h e o t h e r h a n d , p r o d u c t s f o r m e d i n t h e s o l i d a r e m a i n l y d i m e r s w h i c h w e r e a s s u m e d t o b e p r o d u c e d b y t h e f o r m a t i o n a n d s u b s e q u e n t d i m e r i z a t i o n o f c y c l o p e n t a d i e n o n e 7 . T h e t h i r d e x a m p l e i s c h o s e n f r o m a s e r i e s o f i n v e s t i g a t i o n s o n t h e p h o t o c h e m i s t r y o f a , / 9 - a n d / 3 , 7 - u n s a t u r a t e d k e t o n e s b y S c h e f f e r , T r o t t e r a n d c o - w o r k e r s . ^ A s s h o w n i n S c h e m e 1 , c o m p o u n d 8 g i v e s c o m p l e t e l y d i f f e r e n t r e s u l t s u p o n i r r a d i a t i o n i n t h e t w o m e d i a . I n b e n z e n e , t e t r a c y c l i c d i k e t o n e 9 i s f o r m e d , w h e r e a s t r i c y c l i c i s o m e r 10 i s o b s e r v e d i n t h e c r y s t a l l i n e p h a s e . T h e a u t h o r s e s t a b l i s h e d t h e s t r u c t u r e - r e a c t i v i t y r e l a t i o n s h i p s i n t h i s p h o t o t r a n s f o r m a t i o n b a s e d o n c r y s t a l l o g r a p h i c s t u d i e s . - 6 -T h e t h r e e e x a m p l e s a b o v e c l e a r l y d e m o n s t r a t e t h a t m o l e c u l a r c r y s t a l l a t t i c e h a s a r e m a r k a b l e i n f l u e n c e o n t h e c o u r s e a n d s e l e c t i v i t y o f o r g a n i c r e a c t i o n s . I n g e n e r a l , t h e c r y s t a l l i n e e n v i r o n m e n t c o n t r o l s t h e o v e r a l l r e a c t i o n p a t h w a y s , a n d t h i s e n v i r o n m e n t p r o v i d e s o r g a n i c c h e m i s t s w i t h a n e n t i r e l y n e w m e t h o d t o s t u d y c h e m i c a l p r o c e s s e s . I t i s w o r t h m e n t i o n i n g t h a t i t i s e a s i e r t o c o n d u c t o r g a n i c p h o t o r e a c t i o n s i n t h e s o l i d s t a t e t h a n t o p e r f o r m t h e r m a l s o l i d s t a t e r e a c t i o n s . T h e c r y s t a l l i n i t y o f t h e s a m p l e i s n o r m a l l y p r e s e r v e d d u r i n g i r r a d i a t i o n o f t h e c r y s t a l s , w h i l e t h e r m a l r e a c t i o n s o f t e n r e s u l t i n m e l t i n g o f t h e c r y s t a l s . I n t h e c a s e t h a t c r y s t a l m e l t i n g a c c o m p a n i e s t h e r e a c t i o n p r o c e s s , t h e s e l e c t i v i t y w i l l n o r m a l l y b e l o w e r o w i n g t o t h e l o s s o f t o p o c h e m i c a l c o n t r o l . A l t h o u g h c o n s i d e r a b l e p r o g r e s s h a s b e e n m a d e i n t h e l a s t two d e c a d e s i n t h e s t u d y o f o r g a n i c s o l i d s t a t e c h e m i s t r y , p h o t o c h e m i s t r y i n p a r t i c u l a r , m u c h r e m a i n s t o b e l e a r n e d . I n t h i s f i e l d , many o f t h e g e n e r a l r u l e s o f s o l u t i o n p h a s e o r g a n i c c h e m i s t r y d o n o t a p p l y , a n d m o s t o f t h e i n v e s t i g a t i o n s o n t h i s s u b j e c t h a v e b e e n , a n d c o n t i n u e t o b e , a t a d e s c r i p t i v e s t a g e . T h a t i s , t h e m a i n t a s k o f a s o l i d s t a t e c h e m i s t i s t o e x p l a i n t h e r e s u l t s w h e n a n u n e x p e c t e d o b s e r v a t i o n h a s b e e n m a d e i n a s o l i d r e a c t i o n . P a r t o f t h e r e a s o n l i e s i n o u r p r e s e n t i n a b i l i t y t o p r e d i c t t h e p a c k i n g a r r a n g e m e n t s o f o r g a n i c m o l e c u l e s a n d o u r i n s u f f i c i e n t u n d e r s t a n d i n g o f c l o s e m o l e c u l a r i n t e r a c t i o n s i n c r y s t a l s . - 7 -I I . T h e T o p o c h e m i c a l P r i n c i p l e O r g a n i c m o l e c u l a r r e a c t i o n s o c c u r r i n g i n t h e s o l i d s t a t e o f t e n d i f f e r f r o m r e a c t i o n i n i s o t r o p i c o r f l u i d m e d i a . T h i s i s d u e t o t h e f a c t t h a t t h e r e a c t a n t s i n t h e c r y s t a l s e n s e t h e p h y s i c a l r e s t r a i n t s g i v e n b y t h e o t h e r c l o s e l y p a c k e d m o l e c u l e s a n d t h i s c r y s t a l l i n e e n v i r o n m e n t c o n s t r a i n s t h e m o l e c u l e s o r g r o u p s i n t h e i r t h r e e -d i m e n s i o n a l m o b i l i t y a l o n g t h e r e a c t i o n c o o r d i n a t e . I n c o n t r a s t , a t o m i c a n d m o l e c u l a r m o t i o n s i n s o l u t i o n a r e f r e e o f s u c h r e s t r a i n t s , a n d i t i s w e l l a c c e p t e d t h a t t h e r e a c t i v i t y o f o r g a n i c m o l e c u l e s i n s o l u t i o n a r e c o n t r o l l e d b y s u c h f a c t o r s a s e l e c t r o n i c a n d s t e r i c e f f e c t s . T h e t o p o c h e m i c a l p r i n c i p l e t h a t u n d e r l i e s t h e e n t i r e f i e l d o f o r g a n i c s o l i d s t a t e c h e m i s t r y w a s o r i g i n a l l y p o s t u l a t e d b y K o h l s h u t t e r i n 1 9 1 8 . ^ A c c o r d i n g t o K o h l s h u t t e r , a t o p o c h e m i c a l l y c o n t r o l l e d r e a c t i o n i s o n e i n w h i c h t h e n a t u r e o f t h e p r o d u c t s i s g o v e r n e d b y t h e i n f l u e n c e o f t h e t h r e e - d i m e n s i o n a l l y p e r i o d i c a r r a n g e m e n t o f t h e m o l e c u l e s i n t h e o s o l i d . T h i s c o n c e p t w a s t e r m e d t h e " t o p o c h e m i c a l p o s t u l a t e " . H o w e v e r , n o t m u c h p r o g r e s s w a s made o n t h e s t u d y o f t h e s o l i d c h e m i s t r y u n t i l t h e e a r l y 1 9 6 0 s w h e n S c h m i d t a n d c o - w o r k e r s s t a r t e d s y s t e m a t i c i n v e s t i g a t i o n s o f s o l i d s t a t e [2+2] p h o t o d i m e r i z a t i o n s b y m a k i n g u s e o f t h e p o w e r f u l t e c h n i q u e o f X - r a y c r y s t a l l o g r a p h i c a n a l y s i s . A s a r e s u l t o f t h e i r i n t e n s i v e s t u d i e s o n t h e f a c t o r s t h a t c o n t r o l t h e c o u r s e o f o r g a n i c s o l i d s t a t e p h o t o r e a c t i o n s , S c h m i d t a n d c o - w o r k e r s p r o v i d e d s t r o n g e x p e r i m e n t a l e v i d e n c e f o r t h e t o p o c h e m i c a l p o s t u l a t e a n d s t a t e d t h a t r e a c t i o n s i n t h e s o l i d s t a t e p r o c e e d w i t h m i n i m a l a t o m i c a n d q m o l e c u l a r m o v e m e n t . S i n c e t h e n , t h e t o p o c h e m i c a l p o s t u l a t e h a s b e e n - 8 -u s e d a s a f u n d a m e n t a l p r i n c i p l e i n o r g a n i c s o l i d s t a t e p h o t o c h e m i s t r y , a n d p r o v i d e s a b a s i c u n d e r s t a n d i n g o f a l a r g e n u m b e r o f s o l i d s t a t e p h o t o i n d u c e d r e a c t i o n s . A n e l e g a n t e x a m p l e f r o m t h e w o r k o f S c h m i d t a n d c o - w o r k e r s ^ o n t h e p h o t o c y c l o a d d i t i o n s o f trans-cinnamic a c i d s i n t h e s o l i d s t a t e w h i c h b e s t e l u c i d a t e s t h i s b a s i c p r i n c i p l e i s d e p i c t e d i n S c h e m e 2. 1 4 S c h e m e 2 P h o t o c h e m i c a l [2+2] C y c l o a d d i t i o n s o f trans-Cinnamic A c i d i n t h e C r y s t a l l i n e S t a t e . - 9 -t r a n s - C i n n a m i c a c i d ( 1 1 ) c r y s t a l l i z e s i n t h r e e d i f f e r e n t m o r p h o l o g i e s k n o w n a s t h e a - , /9- a n d 7 - f o r m s . T h e a - f o r m , w h i c h i s c h a r a c t e r i z e d b y a n i n t e r m o l e c u l a r c e n t e r - t o - c e n t e r d i s t a n c e b e t w e e n d o u b l e b o n d s o f 3 . 6 - 4 . 1 A , l e d t o t h e f o r m a t i o n o f t h e c e n t r o - s y m m e t r i c a - t r u x i l i c a c i d 12 u p o n U V i r r a d i a t i o n . T h e / } - t y p e c r y s t a l s , w i t h a s e p a r a t i o n d i s t a n c e o f 3 . 9 - 4 . 1 A b e t w e e n t h e t w o d o u b l e b o n d s a n d a p l a n e o f s y m m e t r y b e t w e e n two r e a c t i n g m o l e c u l e s , f o r m e d m i r r o r -s y m m e t r i c / 3 - t r u x i l i c a c i d 1 3 . I n c o n t r a s t , n o r e a c t i o n was o b s e r v e d i n t h e 7 - m o d i f i c a t i o n o f trans-cinnamic a c i d , w h i c h h a s a c e n t e r - t o - c e n t e r d i s t a n c e o f 4 . 7 - 5 . 1 A a n d a n o n - p a r a l l e l m o l e c u l a r a r r a n g e m e n t i n t h e c r y s t a l . I n s o l u t i o n , trans-cinnamic a c i d ( 1 1 ) u n d e r w e n t o n l y trans-cis p h o t o i s o m e r i z a t i o n , a n d n o d i m e r i z a t i o n was o b s e r v e d . B a s e d o n t h e p h o t o c h e m i c a l a n d c r y s t a l l o g r a p h i c s t u d i e s o f a l a r g e n u m b e r o f c i n n a m i c a c i d s , S c h m i d t a n d c o - w o r k e r s e s t a b l i s h e d s t r u c t u r e -r e a c t i v i t y r e l a t i o n s h i p s f o r [2+2] p h o t o d i m e r i z a t i o n s i n t h e c r y s t a l l i n e p h a s e . T h e y s u g g e s t e d t h a t t h e f a c t o r s t h a t c o n t r o l t h e c o u r s e o f s o l i d s t a t e [2+2] c y c l o a d d i t i o n s l i e i n t h e s e p a r a t i o n d i s t a n c e a n d t h e i n t e r m o l e c u l a r a r r a n g e m e n t o r m u t u a l o r i e n t a t i o n o f t h e r e a c t i n g 9 10 m o l e c u l e s i n t h e c r y s t a l s . S c h m i d t ' p r o p o s e d a max imum i n t e r m o l e c u l a r s e p a r a t i o n o f 4 . 2 A b e t w e e n t h e p a r a l l e l a l i g n e d r e a c t i v e d o u b l e b o n d s a s a g e n e r a l r u l e i n t h e s o l i d s t a t e [2+2] d i m e r i z a t i o n s . D e s p i t e some e x c e p t i o n s , ^ t h i s w e l l a c c e p t e d c r i t e r i o n h a s b e e n met a m o n g many s u b s e q u e n t s o l i d s t a t e p h o t o d i m e r i z a t i o n s . - 10 -I I I . R e a c t i v i t y a n d S e l e c t i v i t y o f O r g a n i c R e a c t i o n s i n t h e C r y s t a l l i n e S t a t e R e p r e s e n t i n g a f u l l y a l l o w e d t o p o c h e m i c a l r e a c t i o n , a s i n g l e -c r y s t a l t o s i n g l e - c r y s t a l o r s o - c a l l e d t o p o t a c t i c t r a n s f o r m a t i o n ' ' " ' ' " i s o n e i n w h i c h a s o l i d s a m p l e p r e s e r v e s i t s c r y s t a l l i n i t y a s r e a c t a n t s a r e c o m p l e t e l y c o n v e r t e d i n t o p r o d u c t s . I n s u c h c a s e n o t o n l y t h e n a t u r e a n d s t e r e o c h e m i s t r y o f t h e p r o d u c t a r e n e a r l y t h e s a m e a s t h o s e o f t h e r e a c t i n g m o l e c u l e ( s ) p a c k e d w i t h i n t h e p e r f e c t l a t t i c e , b u t a l s o t h e m o l e c u l a r m o t i o n s a r e k e p t t o a m i n i m u m . A m o n g t h e f e w k n o w n e x a m p l e s o f s i n g l e - c r y s t a l t o s i n g l e - c r y s t a l r e a c t i o n s , t h e p h o t o d i m e r i z a t i o n o f b e n z y l i d e n e c y c l o p e n t a n o n e 15 ( S c h e m e 3) , s t u d i e d b y J o n e s a n d 19 1 i L T h o m a s , " » - • ' » • - d e s e r v e s t o b e m e n t i o n e d . 15 16 S c h e m e 3 P h o t o d i m e r i z a t i o n o f B e n z y l i d e n e c y c l o p e n t a n o n e . C r y s t a l l o g r a p h i c a n a l y s i s d e m o n s t r a t e d b o t h t h e s t r u c t u r a l s i m i l a r i t y a n d t h e s i m i l a r i t y i n c e l l d i m e n s i o n s b e t w e e n t h e r e a c t i v e m o n o m e r s a n d t h e d i m e r s a s s h o w n i n F i g u r e 1. F r o m t h e p a c k i n g a r r a n g e m e n t , i t a l s o r e v e a l e d t h a t t h e d i m e r i z a t i o n p r o c e s s r e q u i r e s 11 -l i t t l e m o t i o n o f t h e a t o m s . I t s h o u l d b e p o i n t e d o u t , h o w e v e r , t h a t t h e v a s t m a j o r i t y o f o r g a n i c s o l i d s t a t e p h o t o r e a c t i o n s s t u d i e d s o f a r d o n o t b e l o n g t o t h i s c a t e g o r y . I n m o s t c a s e s , t h e c r y s t a l l a t t i c e i s d e s t r o y e d d u e t o t h e f o r m a t i o n o f p r o d u c t s . F i g u r e 1 C o m p o s i t e D i a g r a m C o m p a r i n g t h e P a c k i n g o f t h e M o l e c u l a r U n i t s w i t h i n t h e M o n o m e r a n d D i m e r C r y s t a l S t r u c t u r e s o f B e n z y l i d e n e c y c l o p e n t a n o n e . I t i s u n d e r s t o o d t h a t t h e c r y s t a l l a t t i c e e x e r t s s p e c i f i c a l l y d i f f e r e n t e f f e c t s i n d i f f e r e n t d i r e c t i o n s , t h e r e f o r e t h e r e a c t i o n t a k i n g p l a c e i n t h e c r y s t a l i s a n i s o t r o p i c . U n d e r c e r t a i n c i r c u m s t a n c e s , e x t r e m e l y l a r g e s t r a i n s f r o m t h e c r y s t a l l i n e e n v i r o n m e n t may d i s f a v o r a c e r t a i n r e a c t i o n e v e n t h o u g h t h e r e a c t i n g m o l e c u l e s p a c k w i t h i n a b o n d i n g d i s t a n c e a n d w i t h a f a v o r a b l e o r i e n t a t i o n . C o h e n ' ' " r e c o g n i z e d s u c h a n i s o t r o p i c e f f e c t s a n d i n c o r p o r a t e d t h e m u n d e r t h e i n t u i t i v e c o n c e p t o f t h e " r e a c t i o n c a v i t y " . C o h e n r e a s o n e d t h a t t h e r e a c t i n g m o l e c u l e s i n a c r y s t a l o c c u p y a c e r t a i n v o l u m e w i t h a w e l l d e f i n e d - 12 -s h a p e . T h i s space o c c u p i e d b y the r e a c t i n g m o l e c u l e ( s ) i s d e f i n e d as the " r e a c t i o n c a v i t y " and i t i s s u r r o u n d e d by t h e o t h e r c l o s e l y p a c k e d m o l e c u l e s . The a t o m i c movement c o n s t i t u t i n g t h e r e a c t i o n w i l l c a u s e p r e s s u r e on t h e c a v i t y w a l l , w h i c h w i l l t e n d to become d i s t o r t e d . However , any s u c h d i s t o r t i o n i n shape w i l l be r e s i s t e d b y the c l o s e l y p a c k e d e n v i r o n m e n t , and c o n s e q u e n t l y o n l y t h o s e r e a c t i o n s i n v o l v i n g m i n i m a l , change o r d i s t o r t i o n w i l l be f e a s i b l e ( F i g u r e 2). I n o t h e r w o r d s , the t o p o c h e m i c a l p o s t u l a t e c a n be e x t e n d e d t o " r e a c t i o n s t h a t p r o c e e d u n d e r l a t t i c e c o n t r o l do so w i t h m i n i m a l change o r d i s t o r t i o n o f the s u r f a c e o f the r e a c t i o n cavity".''""' T h i s c o n c e p t has p r o v e d to be v e r y u s e f u l i n i n t e r p r e t i n g a v a r i e t y o f t h e o r g a n i c s o l i d s t a t e r e a c t i o n s , e s p e c i a l l y where more t h a n one r e a c t i o n pathway i s a l l o w e d . F i g u r e 2 P i c t o r i a l R e p r e s e n t a t i o n o f " R e a c t i o n C a v i t y " C o n c e p t . S c h e f f e r , T r o t t e r a n d c o - w o r k e r s ^ have i d e n t i f i e d and s y s t e m a t i c a l l y s t u d i e d s p e c i f i c i n t e r m o l e c u l a r e f f e c t s t h a t c o n t r o l the s o l i d s t a t e p h o t o r e a c t i v i t y o f e n e - d i o n e , c y c l o h e x e n o n e , c y c l o h e x a -- 13 -d i e n o n e and b a r r e l e n e compounds. A c e r t a i n e x p e c t e d r e a c t i o n w h i c h does n o t o c c u r i n c r y s t a l s owing t o the s e v e r e s t e r i c i n t e r a c t i o n s be tween t h e r e a c t a n t and i t s s u r r o u n d i n g m o l e c u l e s was d e s c r i b e d to be " s t e r i c c o m p r e s s i o n " c o n t r o l l e d . F o r example , c y c l o h e x e n o n e d e r i v a t i v e 17 shown i n Scheme 4 was f o u n d t o be u n r e a c t i v e t o w a r d [2+2] p h o t o d i m e r i z a t i o n i n t h e s o l i d s t a t e i n s p i t e o f the f a c t t h a t the i n t e r m o l e c u l a r d i s t a n c e and o r i e n t a t i o n between the enone d o u b l e bonds a r e f a v o r a b l e f o r the d i m e r i z a t i o n . NO REACTION n e i g h b o r i n g m o l e c u l e n e i g h b o r i n g m o l e c u l e Scheme 4 R e a c t i o n C o n t r o l l e d by " S t e r i c C o m p r e s s i o n " . - 14 T h i s l a c k o f r e a c t i v i t y was s u g g e s t e d t o b e d u e t o t h e two s p e c i f i c s h o r t c o n t a c t s b e t w e e n t h e m e t h y l g r o u p s f r o m t h e r e a c t i n g m o l e c u l e s a n d t h o s e f r o m t h e n e i g h b o r i n g m o l e c u l e s i n t h e l a t t i c e a s s e e n i n S c h e m e 4 . A n o t h e r e x a m p l e o f s u c h " s t e r i c c o m p r e s s i o n " c o n t r o l l e d s o l i d s t a t e r e a c t i o n h a s a l s o b e e n r e p o r t e d b y S c h e f f e r , T r o t t e r a n d c o - w o r k e r s . ^ M o r e r e c e n t l y , o t h e r t o p o c h e m i c a l c o n s i d e r a t i o n s t h a t a f f e c t r e a c t i v i t y a n d s e l e c t i v i t y i n t h e p h o t o c h e m i s t r y o f o r g a n i c s o l i d s h a v e b e e n i n t r o d u c e d . T h e s e i n c l u d e " d y n a m i c p r e f o r m a t i o n " ( i n t r o d u c e d b y 18 C r a i g t o e m p h a s i z e t h e p o s s i b l e e f f e c t o f e l e c t r o n i c e x c i t a t i o n i n t h e 19 20 21 m o l e c u l a r c r y s t a l ) , " l o c a l s t r e s s " a n d t h e r o l e o f d e f e c t s ' o n s o l i d s t a t e r e a c t i o n s . T h e s e i m p o r t a n t c o n c e p t s h a v e b e e n d i s c u s s e d i n s o m e o f t h e r e v i e w a r t i c l e s , ^ ' ^ a n d w i l l n o t b e i n c l u d e d h e r e . C r y s t a l E n g i n e e r i n g A l t h o u g h a n u m b e r o f r e m a r k a b l e , h i g h l y s t e r e o s e l e c t i v e r e a c t i o n s p r o c e e d s m o o t h l y i n t h e c r y s t a l l i n e p h a s e , t h e s p e c i f i c p a c k i n g a r r a n g e m e n t s i n s i d e t h e c r y s t a l w h i c h a r e r e q u i r e d f o r a c h i e v i n g s u c h h i g h s e l e c t i v i t y a r e g i v e n b y n a t u r e r a t h e r t h a n d e s i g n e d d e l i b e r a t e l y . E v e n t h o u g h a n u n d e r s t a n d i n g o f t h e r e l a t i o n s h i p b e t w e e n s t r u c t u r e a n d r e a c t i v i t y e n a b l e s o n e t o e x p l a i n p r o d u c t f o r m a t i o n a n d r e a c t i o n s e l e c t i v i t y i n many s o l i d s t a t e r e a c t i o n s , t h e s e a r e s t i l l f a r f r o m p r e d i c t i n g t h e p a c k i n g p a t t e r n s o f o r g a n i c m o l e c u l e s i n c r y s t a l s . T h e r e a s o n i s t h a t t h e n a t u r e o f i n t e r m o l e c u l a r f o r c e s i n v o l v e d i n d e t e r m i n i n g t h e c r y s t a l s t r u c t u r e i s n o t y e t s u f f i c i e n t l y u n d e r s t o o d t o a l l o w s e l e c t i o n b e t w e e n a l t e r n a t i v e p o s s i b l e a r r a n g e m e n t s . A t h e o r e t i c a l - 15 a p p r o a c h by a p p l i c a t i o n o f m o l e c u l a r mechan ic s c a l c u l a t i o n s to the s o l i d s t a t e has p r o v e d to be s u c c e s s f u l i n p r e d i c t i n g some c r y s t a l p a c k i n g . ^ 3 To a c h i e v e a d e s i r e d p r o d u c t w i t h s p e c i f i c i t y a n d . t o s t u d y s o l i d s t a t e c h e m i s t r y i n a s y s t e m a t i c way, one needs to know how t o e n g i n e e r a p a r t i c u l a r po lymorphous form p o s s e s s i n g the n e c e s s a r y t o p o c h e m i c a l a t t r i b u t e s t h a t w o u l d l e a d to the d e s i r e d p r o d u c t s . Schmidt w i t h h i s c o l l e a g u e s d e l i n e a t e d v a r i o u s ways o f a c h i e v i n g t h i s and c o i n e d the 9b p h r a s e " c r y s t a l e n g i n e e r i n g " , the i d e a b e i n g to s t e e r m o l e c u l e s t o p a c k i n c e r t a i n p r e - d e t e r m i n e d a r r a n g e m e n t s d u r i n g the growth o f the c r y s t a l s . T o d a y , such " c r y s t a l e n g i n e e r i n g " i s p o s s i b l e , b u t o n l y to a l i m i t e d e x t e n t , on the b a s i s o f some e m p i r i c a l p a c k i n g g e n e r a l i z a t i o n s t h a t have been u n c o v e r e d o v e r the p a s t y e a r s . ^ a a S e v e r a l s u c c e s s f u l a p p r o a c h e s have been r e p o r t e d i n the l i t e r a t u r e , and some o f the p o i n t s a r e o u t l i n e d as f o l l o w s : 1) . C o m p l e x a t i o n o r c o - c r y s t a l l i z a t i o n w i t h m e r c u r i c c h l o r i d e t o a c h i e v e a s e p a r a t i o n d i s t a n c e o f 4 A between d o u b l e bonds f o r 23 p h o t o d i m e r i z a t i o n . 2) . M o n o c h l o r o and d i c h l o r o s u b s t i t u t i o n on a r o m a t i c r i n g s to c o n t r o l t h e p a c k i n g geometry w i t h the s h o r t e s t a x i s o f the u n i t c e l l about 4 A . 2 4 3) . F o r m a t i o n o f mixed c r y s t a l s o r s o l i d s o l u t i o n s by u s i n g c h a r g e - t r a n s f e r i n t e r a c t i o n s o r by i n c o r p o r a t i n g a p h o t o s t a b l e compound i n t o the l a t t i c e o f a p h o t o a c t i v e s u b s t r a t e to b r i n g ( d i f f e r e n t ) 25 p o t e n t i a l r e a c t a n t s i n t o f a c e - t o - f a c e c l o s e p a c k i n g a r r a n g e m e n t s . - 16 I V . A s y m m e t r i c S y n t h e s e s v i a P h o t o r e a c t i o n o f C h i r a l C r y s t a l s A s y m m e t r i c s y n t h e s i s h a s b e e n a n e x t e n s i v e l y s t u d i e d a r e a i n o r g a n i c c h e m i s t r y , a n d many a s y m m e t r i c s y n t h e t i c m e t h o d s h a v e b e e n d e v e l o p e d f o r r e a c t i o n s i n s o l u t i o n p h a s e i n c l u d i n g a s y m m e t r i c p h o t o r e a c t i o n s . T h e b a s i c p r i n c i p l e i n v o l v e s t h e u s e o f a n e x t e r n a l 26 d i s s y m m e t r i c i n f l u e n c e , s u c h a s a r e s o l v e d c h i r a l a g e n t , c h i r a l c a t a l y s t , c h i r a l s o l v e n t o r c i r c u l a r l y p o l a r i z e d l i g h t i n t h e c a s e o f s o m e p h o t o r e a c t i o n s . T h e r e f o r e , o p t i c a l l y a c t i v e c o m p o u n d s c a n b e g e n e r a t e d b y e x e r t i n g s u c h a s y m m e t r i c i n f l u e n c e o n a p r o c h i r a l o r r a c e m i c r e a c t a n t w h i c h l e a d s t o d i a s t e r e o m e r i c t r a n s i t i o n s t a t e s o f d i f f e r e n t e n e r g y . A l t h o u g h a s y m m e t r i c s y n t h e s e s b y p h o t o c h e m i c a l r e a c t i o n s i n s o l u t i o n h a v e b e e n c a r r i e d o u t i n a n u m b e r o f c a s e s , t h e 27 m e t h o d i s l i m i t e d o w i n g t o l o w o p t i c a l y i e l d s . \ I t i s a l s o k n o w n t h a t a s y m m e t r i c s y n t h e s i s c a n a l s o b e p e r f o r m e d i n t h e s o l i d p h a s e . T h i s i s r e f l e c t e d b y t h e f a c t t h a t c r y s t a l c h i r a l i t y c a n b e t r a n s f o r m e d i n t o p e r m a n e n t m o l e c u l a r c h i r a l i t y v i a a 2 8 t o p o c h e m i c a l l y c o n t r o l l e d s o l i d s t a t e r e a c t i o n . I n r e c e n t y e a r s , s u c h a s y m m e t r i c t r a n s f o r m a t i o n s w i t h h i g h o p t i c a l y i e l d s h a v e b e e n a c h i e v e d 3 29 b y u s i n g t h e c h i r a l i n f l u e n c e f r o m m o l e c u l a r c r y s t a l s . ' We k n o w t h a t m o l e c u l a r c h i r a l i t y r e s u l t s f r o m t h e d i s s y m m e t r i c , t h r e e - d i m e n s i o n a l a r r a n g e m e n t o f t h e c o n s t i t u e n t a t o m s o r g r o u p s , w h e r e a s c r y s t a l c h i r a l i t y c a n b e c o n s i d e r e d t o b e d u e t o t h e s i m i l a r s p a t i a l a r r a n g e m e n t o f t h e m o l e c u l e s i n t h e c r y s t a l . I t h a s b e e n e s t a b l i s h e d t h a t t h e r e i s a t o t a l o f 230 s p a c e g r o u p s i n r e l a t i o n t o t h e 17 symmetry o f c r y s t a l s . These r e p r e s e n t the d i f f e r e n t symmetry a r r a n g e m e n t s i n w h i c h m o l e c u l e s may p a c k . They c a n be c l a s s i f i e d as c h i r a l o r a c h i r a l d e p e n d i n g on the p r e s e n c e o r absence o f c e r t a i n symmetry e l e m e n t s . The c h i r a l space g r o u p s , 65 o u t o f the 230 p o s s i b l e o n e s , c o n t a i n o n l y symmetry e l ements o f the f i r s t k i n d , i . e . , t r a n s l a t i o n s , r o t a t i o n s and c o m b i n a t i o n s o f t h e s e . The most common c h i r a l space groups f o r o r g a n i c m o l e c u l e s a r e m o n o c l i n i c P2i and o r t h o r h o m b i c P2]2\2\. The 165 a c h i r a l space g r o u p s p o s s e s s the symmetry e l ements o f the f i r s t k i n d and o f the s e c o n d k i n d s u c h as m i r r o r o r g l i d e p l a n e s a n d / o r c e n t e r s o f i n v e r s i o n . I t i s w e l l known t h a t a l l o p t i c a l l y a c t i v e m o l e c u l e s must c r y s t a l l i z e i n c h i r a l space g r o u p s , and i t i s a l s o known t h a t even h i g h l y s y m m e t r i c a l m o l e c u l e s (which a r e a c h i r a l ) c a n form c h i r a l c r y s t a l s . F o r a r a c e m i c m i x t u r e , i t may e i t h e r a g g r e g a t e to form a n o n -c h i r a l r a c e m i c compound, o r undergo a spontaneous r e s o l u t i o n where the two e n a n t i o m e r s s e g r e g a t e i n t o a c o n g l o m e r a t e o f c h i r a l c r y s t a l s . One s u c h famous example i s the s e p a r a t i o n o f r a c e m i c sod ium ammonium 30 t a r t r a t e i n t o p u r e enant iomorphous c r y s t a l s b y P a s t e u r . I t i s o b v i o u s t h a t the e f f o r t o f a c h i e v i n g h i g h a s y m m e t r i c i n d u c t i o n via c h e m i c a l r e a c t i o n s i n the s o l i d s t a t e . w i l l be f o c u s e d on t h o s e o r g a n i c m o l e c u l e s t h a t c r y s t a l l i z e i n any o f the 65 c h i r a l space g r o u p s , a l t h o u g h under c e r t a i n c i r c u m s t a n c e s some asymmetr i c s y n t h e s e s have r e c e n t l y been 3z a c h i e v e d by u s i n g n o n - c h i r a l o r c e n t r o - s y m m e t r i c c r y s t a l s . 18 A b s o l u t e A s y m m e t r i c S y n t h e s i s A s i t i s m e n t i o n e d a b o v e , a c h i r a l o r g a n i c m o l e c u l e s may c r y s t a l l i z e i n e i t h e r c h i r a l o r a c h i r a l s p a c e g r o u p s . I n t h e f o r m e r c a s e , t h e m o l e c u l e s i n t h e c r y s t a l e x p e r i e n c e a c h i r a l c r y s t a l l i n e e n v i r o n m e n t . P r o v i d e d t h a t o n e o r m o r e c h i r a l c e n t e r s a r e g e n e r a t e d i n t h e s o l i d s t a t e r e a c t i o n , t h e c r y s t a l c h i r a l i t y may b e c o n v e r t e d i n t o p e r m a n e n t m o l e c u l a r c h i r a l i t y i n t h e p r o d u c t b y a t o p o c h e m i c a l l y c o n t r o l l e d p r o c e s s . S u c h a p r o c e s s t h a t g e n e r a t e s o p t i c a l l y a c t i v e p r o d u c t s i n t h e a b s e n c e o f a n y e x t e r n a l c h i r a l i n f l u e n c e i s r e f e r r e d t o 31 a n " a b s o l u t e a s y m m e t r i c s y n t h e s i s " . -. T h i s s p e c i f i c t r a n s f o r m a t i o n c a n n o t b e p e r f o r m e d i n s o l u t i o n , w h e r e a s y m m e t r i c i n d u c t i o n m u s t b e t r a n s f e r r e d f r o m o n e c h i r a l s y s t e m i n t o a n o t h e r . T h e r e f o r e , t h e a b s o l u t e a s y m m e t r i c s y n t h e s i s may s e r v e a s a m o d e l p r o c e s s f o r t h e e x p l a n a t i o n o f 28b 32 t h e o r i g i n o f c h i r a l i t y i n t h e m o l e c u l e s o f n a t u r e . ' S e v e r a l e x a m p l e s s e l e c t e d f r o m t h e l i t e r a t u r e a r e s h o w n i n S c h e m e s 5 , 6 a n d 7 . S y s t e m a t i c s t u d i e s o f b i m o l e c u l a r [2+2] p h o t o c y c l o a d d i t i o n r e a c t i o n s a i m e d a t a s y m m e t r i c s y n t h e s i s i n t h e s o l i d s t a t e w e r e c a r r i e d 98 33 o u t b y S c h m i d t a n d c o - w o r k e r s . ' I r r a d i a t i o n o f s i n g l e c r y s t a l s o f p u r e 18 o r 19 g a v e t h e o p t i c a l l y i n a c t i v e c y c l o b u t a n e d e r i v a t i v e s 20 a n d 21 r e s p e c t i v e l y . H o w e v e r , w h e n d i l u t e (15%) s o l i d s o l u t i o n s o f 19 i n 1 8 , s p a c e g r o u p P 2 ^ 2 ^ 2 i , w e r e p r e p a r e d a n d t h e l o n g e r w a v e l e n g t h a b s o r b i n g t h i o p h e n e c o m p o u n d 19 s e l e c t i v e l y p h o t o l y z e d , a 70% e n a n t i o m e r i c e x c e s s o f t h e c h i r a l h e t e r o d i m e r 22 was a c h i e v e d . - 19 -Scheme 5 Absolute Asymmetric Synthesis by S o l i d State [2+2] Photocycloaddition. Following the pioneering work of Schmidt et al. , several other asymmetric transformations were reported. As shown i n Scheme 6, Scheffer, T r o t t e r and co-workers demonstrated that the adamantyl ketone de r i v a t i v e 23 c r y s t a l l i z e s i n the c h i r a l space group ?7.\2.\2\. I r r a d i a t i o n of a sing l e c r y s t a l of t h i s ketone res u l t e d i n the formation of the cyclobutanol d e r i v a t i v e 25 via the Norrish type II reaction with approximately 80% e.e. A second example was also o f f e r e d by Scheffer, Trotter and co-workers. Upon i r r a d i a t i o n of a c h i r a l s i n g l e c r y s t a l (space group P2]^2i2]^), dibenzobarrelene d i e s t e r 26 underwent a unimolecular rearrangement to a f f o r d dibenzosemibullvalene d e r i v a t i v e 27 with quantitative enantiomeric excess. In contrast, photolysis of the same compound i n an a c h i r a l c r y s t a l modification (space group Pbca) gave no o p t i c a l a c t i v i t y . By determining the absolute configurations of both the reacting molecule i n the c h i r a l single c r y s t a l and i t s o p t i c a l l y 20 a c t i v e p h o t o p r o d u c t , the a u t h o r s d e m o n s t r a t e d t h a t t h i s p h o t o t r a n s f o r m a t i o n p r o c e e d s s t e r e o s p e c i f i c a l l y t h r o u g h one o f t h e f o u r d e g e n e r a t e pathways i n the s o l i d s t a t e . 24 , 25 C0 2R 26 27 Scheme 6 A b s o l u t e A s y m m e t r i c S y n t h e s e s v i a N o r r i s h Type I I and D i - 7 r -Methane R e a c t i o n s i n the S o l i d S t a t e . 35 As shown i n Scheme 7, Toda and c o - w o r k e r s f o u n d t h a t i r r a d i a t i o n o f N , N - d i i s o p r o p y l p h e n y l g l y o x y l a m i d e (28) i n s i n g l e c h i r a l c r y s t a l form ( space group P2\2-[2\) l e d to the f o r m a t i o n o f the o p t i c a l l y a c t i v e f3-l a c t a m 29 w i t h 93% e . e . - 21 -OH Me P h . P i r ^ j f ^ ^ P r i c r y s t a l " J [ P r l 28 29 Scheme 7 Absolute Asymmetric Synthesis of ^-Lactam 29. The examples above c l e a r l y indicate that s t e r e o s p e c i f i c asymmetric transformations can be achieved by converting c r y s t a l c h i r a l i t y into permanent molecular c h i r a l i t y . Owing to the s t r i c t requirements for such processes, however, the development of new systems appropriate for such asymmetric syntheses has been slow. So f a r , only a few examples'^2' ^  of absolute asymmetric synthesis have been described i n c l u d i n g the e a r l i e r report of an asymmetric g a s - s o l i d bromination r e a c t i o n by Penzien and 37 Schmidt. It i s f a r from common that a c h i r a l organic molecules spontaneously c r y s t a l l i z e i n c h i r a l space groups and undergo chemical reactions i n such media to give o p t i c a l l y a c t i v e products. Even i n some cases where these conditions have been met, one needs to use r e l a t i v e l y large c h i r a l single c r y s t a l s to conduct such asymmetric transformations i n a p r a c t i c a l way. Another d i f f i c u l t y i s that the f i e l d of c r y s t a l engineering i s not so advanced that the desired c h i r a l space group of organic c r y s t a l s can be achieved. - 22 -T h e a p p r o a c h t o o v e r c o m e t h e s e p r o b l e m s i s t o u s e r e s o l v e d c h i r a l m o l e c u l e s , s i n c e a l l o p t i c a l l y p u r e c o m p o u n d s m u s t c r y s t a l l i z e i n c h i r a l s p a c e g r o u p s . I n t h e c h i r a l c r y s t a l s t h a t c o n s i s t o f o p t i c a l l y a c t i v e m o l e c u l e s , t h e r e a c t i n g m o l e c u l e s e n s e s a c h i r a l e n v i r o n m e n t . T h e r e f o r e , t h e a s y m m e t r i c i n d u c t i o n w i l l b e c a u s e d n o t o n l y b y t h e c h i r a l c e n t e r o f t h e m o l e c u l e b u t a l s o b y t h e c h i r a l c r y s t a l l i n e f i e l d . T h i s i s i n c o n t r a s t t o t h e s i t u a t i o n i n s o l u t i o n , w h e r e t h e a s y m m e t r i c i n d u c t i o n i s e x e r t e d s o l e l y b y t h e c h i r a l c e n t e r o f t h e m o l e c u l e . F o r t h e p u r p o s e o f s t u d y i n g a s y m m e t r i c s y n t h e s i s i n t h e s o l i d s t a t e , t h e c h i r a l c e n t e r u s e d a s a c h i r a l h a n d l e c a n b e d e s i g n e d i n s u c h a w a y t h a t i t i s r e l a t i v e l y f a r a w a y f r o m t h e s i t e o f r e a c t i o n . I d e a l l y , t h e c h i r a l h a n d l e w o u l d b e l o c a t e d a t a s i t e s u f f i c i e n t l y r e m o t e s o t h a t n o a s y m m e t r i c i n d u c t i o n i s e x e r t e d w h e n t h e r e a c t i o n i s c a r r i e d o u t i n s o l u t i o n . T h e r e b y , t h e r o l e o f t h e c h i r a l h a n d l e i s s i m p l y t o f o r c e t h e m o l e c u l e i n t o a c h i r a l l a t t i c e . U n d e r t h e s e c o n d i t i o n s , t h e a s y m m e t r i c i n d u c t i o n I n t h e s o l i d s t a t e c a n b e a t t r i b u t e d e x c l u s i v e l y t o t h e c h i r a l c r y s t a l l i n e l a t t i c e . I f t h e u n r e a c t i v e c h i r a l h a n d l e i s r e m o v a b l e a f t e r t h e r e a c t i o n , t h e o p t i c a l a c t i v i t y o f t h e p r o d u c t c a n t h e n b e d e t e r m i n e d . T h i s may p r o v i d e a n a l t e r n a t i v e m e t h o d o f a s y m m e t r i c s y n t h e s i s i n t h e s o l i d s t a t e . V. U n i m o l e c u l a r P h o t o r e a r r a n g e m e n t s M o s t o f t h e r e s e a r c h p a p e r s p u b l i s h e d i n t h e a r e a o f o r g a n i c s o l i d s t a t e c h e m i s t r y d u r i n g t h e p a s t 25 y e a r s h a v e b e e n c o n c e r n e d w i t h b i m o l e c u l a r r e a c t i o n s , e s p e c i a l l y i n t e r m o l e c u l a r [2+2] p h o t o c y c l o -a d d i t i o n s , f i r s t s t u d i e d b y S c h m i d t w i t h h i s c o l l a b o r a t o r s a t t h e - 23-Weizmann I n s t i t u t e of Science. Approximately f i f t e e n years ago, Scheffer, T r o t t e r and co-workers i n i t i a t e d systematic investigations on unimolecular photorearrangement reactions i n the c r y s t a l l i n e state. In contrast to bimolecular s o l i d state processes, where the r o l e of the c r y s t a l l a t t i c e i s p r i m a r i l y one of l o c a t i n g a p a i r of reacting molecules wi t h i n bonding distance of one another with an o r i e n t a t i o n favorable f o r reaction, unimolecular reactions occurring i n organic c r y s t a l s are c o n t r o l l e d mainly by intramolecular geometric conformational factors. Although the c r y s t a l l a t t i c e s t i l l plays an important r o l e , i t has been considered that the packing arrangement exerts i t s influence mainly as a dynamic e f f e c t . This dynamic e f f e c t , f i r s t formulated q u a l i t a t i v e l y as the concept of the r e a c t i o n c a v i t y by Cohen, i s r e f l e c t e d i n the t r a n s i t i o n state where the non-bonded repulsive i n t e r a c t i o n s r e s u l t i n g from the atomic and molecular i n t e r a c t i o n s of the reactant with i t s surrounding molecules determine which pathways w i l l be traversed. Very often they are those with the l e a s t motions. A. Photorearrangement of Cyclohexenone Systems One of the model reaction systems studied i n t h i s thesis i s the photorearrangement of 4,4-diarylcyclohexenones. Unimolecular rearrangement of 4,4-disubstituted cyclohexenones i n s o l u t i o n has been the subject of intensive study for nearly 30 years, not only from the viewpoint of mechanistic i n t e r e s t s but also i n i t s synthetic 38 a p p l i c a t i o n s . Several reviews on this subject have appeared, which - 24 -best summarize the important features of these c l a s s i c photorearrangements. Normally upon photolysis i n organic solvents, 4,4-dialkyl substituted cyclohexenones undergo unimolecular rearrangement leading to the formation of bicyclo[3.1.0]hexan-2-ones, s o - c a l l e d lumiketones, accompanied by r i n g contraction products. This kind of transformation i s i l l u s t r a t e d by the photorearrangement of 4,4-dimethyl-2-cyclohexen-l-one 39 (30) to the lumiketone 31 and cyclopentenone 32, one of the e a r l i e s t i n v e s t i g a t e d systems (Scheme 8). Scheme 8 Photorearrangement of 4,4-Dimethyl-2-cyclohexen-l-one. I t was pointed out that these reactions are competitive with photodimerization and photoreduction of the enones, and the y i e l d s of the lumiketone 31 are usually optimal i n polar solvents such as t-butanol. Based on a survey of the photochemical behavior of a large number of cyclohexenones, Dauben and co-workers^ concluded that the presence of two substituents at the C-4 p o s i t i o n (at l e a s t one of which - 25 -m u s t b e a n a l k y l g r o u p ) i s n e c e s s a r y f o r t h e f o r m a t i o n o f t h e l u m i k e t o n e . I f o n e o f t h e s u b s t i t u e n t s a t C - 4 i s a n a r y l g r o u p , s u c h a s c o m p o u n d 33, t h e l u m i k e t o n e r e a r r a n g e m e n t w i l l c o m p e t e w i t h p h e n y l m i g r a t i o n ^ a s s h o w n i n S c h e m e 9 . F u r t h e r m o r e w i t h two p h e n y l s u b s t i t u e n t s a t t h e C - 4 p o s i t i o n , s u c h a s f o u n d i n e n o n e 36a, t h e p h e n y l m i g r a t i o n p r o d u c t s 39a a n d 40a a r e e x c l u s i v e . hv + 34 hu Ph m i g r a t i o n • 2 , 4 - b o n d i n g • O 0 Ph Ph 39 a 40a S c h e m e 9 P h o t o t r a n s f o r m a t i o n s o f 4 - P h e n y l - 4 - m e t h y l - 2 - c y c l o h e x e n - l - o n e a n d 4 , 4 - D i p h e n y l - 2 - c y c l o h e x e n - 1 - o n e . - 26 -A l t h o u g h i t m i g h t b e c o n s i d e r e d t h a t t h e p h o t o r e a r r a n g e m e n t o f 4 , 4 - d i a r y l s u b s t i t u t e d c y c l o h e x e n o n e s i s a n e x a m p l e o f t h e d i - 7 r — m e t h a n e r e a r r a n g e m e n t b y a s o m e w h a t p a r a l l e l m e c h a n i s m , t h e r e a c t i o n p r o c e e d s v i a t h e n - 7 r e x c i t e d s t a t e u p o n a b s o r p t i o n o f a p h o t o n a n d i s f o l l o w e d b y m i g r a t i o n o f t h e p h e n y l g r o u p a n d s u b s e q u e n t b o n d f o r m a t i o n b e t w e e n C - 2 a n d C - 4 ( S c h e m e 9 ) . B . T h e D i - 7 r - M e t h a n e R e a r r a n g e m e n t T h e s e c o n d r e a c t i o n u n d e r i n v e s t i g a t i o n i n t h e p r e s e n t t h e s i s i s t h e s o - c a l l e d d i - 7 r — m e t h a n e r e a r r a n g e m e n t , o n e o f t h e m o s t t h o r o u g h l y s t u d i e d p h o t o c h e m i c a l r e a c t i o n s . I t s name i s d e r i v e d f r o m t h e g e n e r a l o b s e r v a t i o n t h a t c e r t a i n o r g a n i c m o l e c u l e s i n w h i c h t w o n—bonds a r e s e p a r a t e d b y a n s p - h y b r i d i z e d o r m e t h a n e c a r b o n a t o m u n d e r g o r e a r r a n g e m e n t u p o n a b s o r p t i o n o f a p h o t o n o f l i g h t t o g i v e v i n y l c y c l o p r o p a n e d e r i v a t i v e s . S c h e m e 10 i l l u s t r a t e s t h e t r a n s f o r m a t i o n o f t h e s i m p l e s t d i - 7 r — m e t h a n e s y s t e m , 1 , 4 - p e n t a d i e n e ( 4 1 ) , a l o n g w i t h t h e m e c h a n i s m p r o p o s e d b y Z i m m e r m a n . I n i t i a l 2 , 4 - b o n d i n g o f t h e t w o n-b o n d s o f 41 g e n e r a t e s b i r a d i c a l 4 2 , a n d t h i s i s f o l l o w e d b y b o n d r e o r g a n i z a t i o n t o b i r a d i c a l 43 a n d r i n g c l o s u r e t o v i n y l c y c l o p r o p a n e 4 4 . 27 -A — - ifV — - ifS • • • v4n y cyd opropon e 41 42 43 44 S c h e m e 10 R e p r e s e n t a t i o n o f a S i m p l e D i - w - M e t h a n e R e a r r a n g e m e n t . T h i s s i m p l e m e c h a n i s m h a s w i d e a p p l i c a t i o n i n p r e d i c t i n g - a n d d e s c r i b i n g a l a r g e n u m b e r o f e x a m p l e s o f t h e d i - 7 r — m e t h a n e r e a r r a n g e m e n t . H o w e v e r , i t i s n e c e s s a r y t o p o i n t o u t t h a t t h e b i r a d i c a l s t r u c t u r e s 42 a n d 43 i n S c h e m e 10 a r e a p p r o x i m a t i o n s o f s p e c i e s a l o n g t h e r e a c t i o n p a t h w a y a n d d o n o t n e c e s s a r i l y r e p r e s e n t t r u e i n t e r m e d i a t e s . S c h e m e 11 s h o w s a v a r i e t y o f e x a m p l e s o f p h o t o r e a r r a n g e m e n t o f t h e d i - 7 r - m e t h a n e s y s t e m s . H e r e i t c a n b e n o t i c e d t h a t b o t h a l i p h a t i c a n d a r o m a t i c it—bonds a r e c a p a b l e o f p a r t i c i p a t i n g i n t h e p r o c e s s . I t s h o u l d b e p o i n t e d o u t t h a t t h e r e a c t i o n m u l t i p l i c i t y i s d e p e n d e n t o n t h e n a t u r e o f t h e m o l e c u l a r s t r u c t u r e . I n g e n e r a l , a c y c l i c d i - 7 r — m e t h a n e r e a c t a n t s r e a r r a n g e e f f e c t i v e l y f r o m t h e i r s i n g l e t e x c i t e d s t a t e s , w h e r e a s c y c l i c o n e s p r e f e r t o u n d e r g o t h e r e a r r a n g e m e n t v i a t h e i r t r i p l e t e x c i t e d s t a t e s . 4 3 - 28 -S c h e m e 11 E x a m p l e s o f t h e D i - 7 r — M e t h a n e P h o t o r e a r r a n g e m e n t . O n e o f t h e e a r l i e s t e x a m p l e s o f t h e d i - 7 r — m e t h a n e r e a r r a n g e m e n t , r e p o r t e d b y Z i m m e r m a n a n d c o - w o r k e r s , 4 ^ i s t h e p h o t o c h e m i c a l c o n v e r s i o n o f b a r r e l e n e 54 t o s e m i b u l l v a l e n e 55 u s i n g a c e t o n e s e n s i t i z a t i o n . I n c o n t r a s t , c y c l o o c t a t e t r a e n e ( 5 6 ) i s t h e m a j o r p r o d u c t u p o n d i r e c t 29 i r r a d i a t i o n . Similar photochemical 49 benzobarrelene 57, the t r i p l e t (58), while benzocyclooctatetraene (Scheme 12). behavior was observed i n the case of rea c t i o n g i v i n g benzosemibullvalene (59) i s formed by d i r e c t i r r a d i a t i o n There are many other examples belonging to t h i s class of barrelene compounds. Among them, dibenzobarrelene d i e s t e r derivatives, such as compound 60, are of s p e c i a l i n t e r e s t i n t h i s t h e s i s . Ciganek"^ was the f i r s t to demonstrate the di-w-methane photorearrangement of dibenzobarrelene 60 i n so l u t i o n . This r e a c t i o n i s consistent with the Zimmerman mechanism, i n which the i n i t i a l step involves bond formation between the v i n y l carbon atom and the neighboring aromatic carbon atom (vinyl-benzo bridging). Subsequent reorganization and the ring closure produce dibenzosemibullvalene d i e s t e r d e r i v a t i v e 63. Scheffer, Trotter 30 and co-workers have recently studied the s o l i d state photorearrangement of the substrate 60 together with some other s i m i l a r d e r i v a t i v e s . They demonstrated that the reactions proceed smoothly i n the c r y s t a l l i n e phase as well as i n s o l u t i o n (Scheme 13). Scheme 13 Photochemical Transformation of Dibenzobarrelene Diester Derivative . When a substituent i s introduced at the 9-position of the dibenzobarrelene system (e.g., compound 64"^ i n Scheme 14), two d i f f e r e n t reaction pathways (path A and path B) leading to a p a i r of regioisomers 67 and 70 can be followed by applying the general mechanism. Based on a number of investigations on the r e g i o s e l e c t i v i t y of the photoreaction of 9-substituted dibenzobarrelenes i n solution, i t 51 52 was suggested ' that the r e g i o s e l e c t i v i t y of such reactions i s 31 -generally determined by the e l e c t r o n i c properties of the 9-substituents, which a f f e c t the r e l a t i v e s t a b i l i t i e s on the i n i t i a l l y formed intermediate species 65 and 68. Scheme 14 The Di-7r—Methane Photorearrangement of 9-Methyl . .. Dibenzobarrelene Diester. 32 V I . O b j e c t i v e s o f P r e s e n t R e s e a r c h I t i s a p p a r e n t f r o m t h e p r e v i o u s d i s c u s s i o n t h a t t h e e s t a b l i s h m e n t o f b a s i c t h e o r i e s a n d f u n d a m e n t a l r u l e s i n s o l i d s t a t e c h e m i s t r y r e q u i r e t h a t m o r e s o l i d s t a t e r e a c t i o n s b e d i s c o v e r e d a n d a b e t t e r u n d e r s t a n d i n g o f s t r u c t u r e - r e a c t i v i t y r e l a t i o n s h i p s b e g a i n e d . T h i s l e a d s t o t h e o b j e c t i v e o f t h e p r e s e n t t h e s i s , t h a t i s t o e x p l o r e m o r e p h o t o c h e m i c a l r e a c t i o n s i n t h e c r y s t a l l i n e p h a s e a n d t o u n d e r s t a n d c r y s t a l l i n e e f f e c t s o n t h e p h o t o r e a c t i v i t y o f o r g a n i c c o m p o u n d s . I t i s p r e f e r a b l e t h a t t h e p h o t o c h e m i s t r y o f t h e m o d e l s y s t e m s c h o s e n f o r s t u d y b e w e l l u n d e r s t o o d i n a n i s o t r o p i c m e d i u m , i . e . s o l u t i o n , s o t h a t t h e p r i m a r y r e s e a r c h e f f o r t w i l l b e f o c u s e d o n t h e e f f e c t o f t h e c r y s t a l l a t t i c e o n r e a c t i v i t y a n d s e l e c t i v i t y . T h e a p p r o a c h a d o p t e d i n t h i s t h e s i s i s p r i m a r i l y o n e o f p r o d u c t a n a l y s i s . I n g e n e r a l , p r o d u c t ( s ) a n d p r o d u c t d i s t r i b u t i o n o f a p h o t o c h e m i c a l t r a n s f o r m a t i o n i n s o l u t i o n a n d i n t h e c r y s t a l l i n e p h a s e a r e s t u d i e d . I f a d i f f e r e n c e e x i s t s b e t w e e n t h e t w o , t h e m a i n t a s k w i l l b e t o s e a r c h t h o s e f a c t o r s t h a t c a u s e t h e d i f f e r e n c e s a n d t o u n d e r s t a n d t h e m f r o m t h e v i e w p o i n t o f t h e c r y s t a l l a t t i c e e f f e c t . F r o m t h i s , i t i s e x p e c t e d t h a t c e r t a i n s t r u c t u r e - r e a c t i v i t y c o r r e l a t i o n s c a n b e e s t a b l i s h e d b a s e d o n X - r a y c r y s t a l l o g r a p h y a n d o t h e r s o l i d s t a t e s t r u c t u r a l a n d s p e c t r o s c o p i c a n a l y s e s . T h e m o d e l s y s t e m i n i t i a l l y s e l e c t e d f o r s t u d y w a s t h e p h o t o i n d u c e d r e a r r a n g e m e n t o f 4 , 4 - d i a r y l s u b s t i t u t e d c y c l o h e x e n o n e s , i n w h i c h t h e b a s i c f e a t u r e s o f t h e p h o t o c h e m i s t r y i n s o l u t i o n h a v e b e e n e s t a b l i s h e d b y Z i m m e r m a n a n d c o - w o r k e r s a s d i s c u s s e d e a r l i e r . T h e f i r s t s e r i e s o f c o m p o u n d s c h o s e n f o r i n v e s t i g a t i o n was 4 - a r y l - 4 - p h e n y l - 2 - c y c l o h e x e n - l -o n e s ( 7 1 a a n d 7 1 b ) a s s h o w n i n S c h e m e 1 5 . U p o n p h o t o l y s i s , t h e e n o n e 71 33 -may l e a d t o t h e f o r m a t i o n o f r e a r r a n g e d p r o d u c t s . A r y l g r o u p m i g r a t i o n g i v e s t h e c o m p o u n d 7 2 . O n t h e o t h e r h a n d , t h e p r o d u c t 73 i s f o r m e d i f p h e n y l g r o u p m i g r a t e s . I n t h e i r s t u d y o f m i g r a t o r y a p t i t u d e o f 4 - a r y l - 4 -53 p h e n y l c y c l o h e x e n o n e s ( 7 1 b a n d 7 1 c ) , Z i m m e r m a n a n d c o - w o r k e r s h a v e d e m o n s t r a t e d t h a t a n e l e c t r o n i c s t a b i l i z i n g e f f e c t w a s r e s p o n s i b l e f o r t h e p r e f e r e n c e o f a r y l g r o u p m i g r a t i o n o v e r p h e n y l m i g r a t i o n i n s o l u t i o n . b . X=CN c . X=OMe S c h e m e 15 P h o t o r e a r r a n g e m e n t o f 4 - A r y l - 4 - p h e n y l c y c l o h e x e n o n e s . I t i s r e a s o n a b l e t o a s s u m e t h a t c h a n g i n g t h e s u b s t i t u e n t X w i l l n o t a f f e c t t h e e l e c t r o n i c s t r u c t u r e o f e i t h e r t h e g r o u n d o r t h e e x c i t e d s t a t e o f t h e e n o n e m o i e t y . T h e r e f o r e , t h e m a i n o b j e c t i v e h e r e i s t o d e t e r m i n e t h e c r y s t a l l a t t i c e e f f e c t e x e r t e d o n t h e m i g r a t o r y a p t i t u d e , a s i t i s c o n s i d e r e d t h a t t h e a r y l g r o u p s w h i c h p r e f e r t o m i g r a t e i n - 34 -s o l u t i o n may n o t m i g r a t e s o w e l l i n s o l i d s t a t e o w i n g t o t h e i r l a r g e r s i z e . A s a n e x t e n s i o n o f t h e a b o v e i d e a s , c o m p o u n d s 7 4 (R = m e t h y l a n d e t h y l ) w e r e d e s i g n e d . A p p l i c a t i o n o f t h e e s t a b l i s h e d m e c h a n i s m p r e d i c t s t h e f o r m a t i o n o f two s t r u c t u r a l i s o m e r s , 75 a n d 7 6 . I t c a n b e a l s o e x p e c t e d t h a t i n t h e s o l i d s t a t e t h e m o l e c u l e s w i l l t a k e t h e i r l o w e s t e n e r g y c o n f o r m a t i o n s , p r e f e r a b l y t h e p s e u d o - c h a i r c o n f o r m a t i o n w i t h t h e m e t h y l g r o u p i n p s e u d o - e q u a t o r i a l p o s i t i o n . I n s u c h c i r c u m s t a n c e s , t h e a i m o f t h e i n v e s t i g a t i o n i s t o f i n d o u t how t h e c r y s t a l l a t t i c e w i l l a f f e c t s t e r e o c h e m i s t r y o f t h e p h o t o p r o d u c t s ( S c h e m e 1 6 ) . S c h e m e 16 P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i p h e n y l - 6 - a l k y l c y c l o h e x e n o n e s . T h e s e c o n d p r o p o s e d a r e a o f r e s e a r c h was t o i n v e s t i g a t e t h e s o l i d s t a t e p h o t o c h e m i s t r y o f 9 - s u b s t i t u t e d d i b e n z o b a r r e l e n e d i e s t e r s ( g e n e r a l - 35 -s t r u c t u r e 7 7 ) , a d i - 7 r — m e t h a n e s y s t e m . U p o n i r r a d i a t i o n i n s o l u t i o n , a u n i m o l e c u l a r r e a r r a n g e m e n t o f t h i s t y p e o f c o m p o u n d s w i l l l e a d t o t h e f o r m a t i o n o f p h o t o p r o d u c t s 78 a n d 79 v i a r e a c t i o n p a t h w a y s A a n d B ( r e f e r t o S c h e m e 1 4 ) r e s p e c t i v e l y . T h e r e g i o s e l e c t i v i t y o f t h i s p h o t o t r a n s f o r m a t i o n i s c o n t r o l l e d b y t h e e l e c t r o n i c p r o p e r t i e s o f t h e 9 -51 5? s u b s t i t u e n t * a s d i s c u s s e d e a r l i e r . T h e f i r s t o b j e c t i v e w a s t o d e t e r m i n e w h e t h e r o r n o t t h e e l e c t r o n i c e f f e c t w o u l d s t i l l b e a p r e d o m i n a n t f a c t o r i n t h e s o l i d s t a t e a n d t o e s t a b l i s h a g e n e r a l t r e n d o f c r y s t a l l a t t i c e e f f e c t s o n t h e r e a c t i v i t y a n d s e l e c t i v i t y o f 9 -s u b s t i t u t e d d i b e n z o b a r r e l e n e d i e s t e r s . I t was c o n s i d e r e d t h a t a n u m b e r o f d e r i v a t i v e s w i t h d i f f e r e n t s u b s t i t u e n t s a t t h e 9 - p o s i t i o n , w h i c h d o n o t d i s t u r b t h e e l e c t r o n i c s t r u c t u r e o f t h e d i - n — m e t h a n e m o i e t y , s h o u l d b e p r e p a r e d i n o r d e r to f a c i l i t a t e t h e i n v e s t i g a t i o n . S c h e m e 17 P h o t o r e a r r a n g e m e n t o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e s 36 T h e s e c o n d m a j o r g o a l was d e r i v e d f r o m t h e f a c t t h a t a r e s o l v e d c h i r a l s u b s t i t u e n t o r h a n d l e a t t h e 9 - p o s i t i o n o f d i b e n z o b a r r e l e n e w o u l d f o r c e t h e m o l e c u l e t o c r y s t a l l i z e i n a c h i r a l s p a c e g r o u p . P h o t o l y s i s o f c r y s t a l s o f t h i s t y p e o f c o m p o u n d s p r o v i d e s a n o p p o r t u n i t y t o s t u d y t h e a s y m m e t r i c i n d u c t i o n s d u e t o t h e i n f l u e n c e o f t h e c h i r a l c r y s t a l l i n e e n v i r o n m e n t . I t w a s t h o u g h t t h a t s u c h i n f l u e n c e m i g h t b e d i f f e r e n t o n t h e two p a t h w a y s ( p a t h A a n d p a t h B ) . I f s o , i t w o u l d b e i n t e r e s t i n g a n d w o r t h w h i l e t o f i n d o u t t h e r e a s o n s t h a t c a u s e d i f f e r e n c e s i n a s y m m e t r i c i n d u c t i o n o n t h e two p a t h w a y s i n t h e s o l i d s t a t e . A n o t h e r i m p o r t a n t o b j e c t i v e o f t h e p r o p o s e d r e s e a r c h w a s t o i n v e s t i g a t e t h e p o s s i b i l i t y t h a t two o r m o r e c r y s t a l m o d i f i c a t i o n s m i g h t d i s p l a y d i f f e r e n t r e a c t i v i t y a n d / o r s e l e c t i v i t y i n t h e s o l i d s t a t e r e a c t i o n . H o w e v e r , t h e e x i s t e n c e o f p o l y m o r p h i s m i s d i f f i c u l t t o p r e d i c t a n d t o c o n t r o l . T h i s h a s b e e n a f a s c i n a t i n g a r e a , s i n c e m o r e d e t a i l e d s t r u c t u r a l i n f o r m a t i o n o n t h e i n f l u e n c e o f r e a c t i o n e n v i r o n m e n t c a n b e o b t a i n e d w h e r e v e r d i f f e r e n t p h o t o c h e m i c a l b e h a v i o r d u e t o c r y s t a l m o r p h o l o g y i s o b s e r v e d . T h e f i n a l o b j e c t i v e o f t h i s t h e s i s w a s d e v e l o p e d , w h i l e t h e r e s e a r c h w a s b e i n g c a r r i e d o u t , f r o m t h e r e a l i z a t i o n t h a t o n e o f t h e t a r g e t m o l e c u l e s u n d e r s t u d y c r y s t a l l i z e d i n a c h i r a l s p a c e g r o u p , b u t t h e m o l e c u l e d o e s n o t p o s s e s s a n y c h i r a l i t y o f i t s o w n . T h e r e f o r e , t h e t r a n s f o r m a t i o n o f c r y s t a l c h i r a l i t y o f t h e a c h i r a l s t a r t i n g m a t e r i a l t o t h e p e r m a n e n t m o l e c u l a r c h i r a l i t y o f t h e p r o d u c t s w a s s t u d i e d . T h i s p r o v i d e d a n o t h e r e x a m p l e o f a b s o l u t e a s y m m e t r i c s y n t h e s i s . - 37 -RESULTS AND DISCUSSION 38 -I. P r e p a r a t i o n o f S t a r t i n g M a t e r i a l s A . S y n t h e s i s o f C y c l o h e x e n o n e S u b s t r a t e s 4 - P h e n y l - 4 - p - b r o m o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 a ) a n d 4 - p h e n y l - 4 -p - c y a n o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 b ) w e r e p r e p a r e d a c c o r d i n g t o t h e 53 p r o c e d u r e s r e p o r t e d b y Z i m m e r m a n et al. ( S c h e m e 1 8 ) . A d d i t i o n o f d i m e t h y l o x o s u l f o n i u m m e t h y l i d e ( 8 1 ) t o p - b r o m o b e n z o p h e n o n e ( 8 0 ) b y t h e m e t h o d o f C o r e y a n d c o - w o r k e r s " ^ y i e l d s t h e c o r r e s p o n d i n g e p o x i d e 8 2 , w h i c h i s a c i d - c a t a l y z e d t o r e a r r a n g e t o a c e t a l d e h y d e 8 3 . C o n d e n s a t i o n o f 83 w i t h m e t h y l v i n y l k e t o n e l e a d s t o t h e f o r m a t i o n o f t h e d e s i r e d c o m p o u n d , 4 - p h e n y l - 4 - p - b r o m o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 a ) . T h e b r o m i d e 7 1 a i s t h e n t r e a t e d w i t h c u p r o u s c y a n i d e b y t h e m e t h o d o f N e w m a n ^ t o g i v e t h e c o r r e s p o n d i n g c y a n o d e r i v a t i v e 7 1 b . 0 + Ph P h B r - p 80 81 82 0 0 Ph CHO P h B r - p OH C u C N P h P h B r - p P h P h C N - p 83 7 1 a 7 1 b S c h e m e 18 S y n t h e s e s o f 4 - p - B r o m o p h e n y l - a n d 4 - p - C y a n o p h e n y l - 4 - p h e n y l -c y c l o h e x e n o n e s . 39 S y n t h e s i s o f t h e C - 6 a l k y l s u b s t i t u t e d c y c l o h e x e n o n e s b e g a n w i t h t h e c o n d e n s a t i o n b e t w e e n , d i p h e n y l a c e t a l d e h y d e ( 8 4 ) a n d m e t h y l v i n y l k e t o n e t o a f f o r d d i p h e n y l c y c l o h e x e n o n e ( 3 6 a ) , w h i c h w a s o r i g i n a l l y p r e p a r e d b y Z i m m e r m a n e t a l . 4 2 A m e t h y l o r a n e t h y l g r o u p w a s t h e n i n t r o d u c e d a t t h e C - 6 p o s i t i o n b y t h e m e t h o d o f a l k y l a t i o n t h r o u g h a n e n o l a t e i n t e r m e d i a t e . " ^ T h i s r e s u l t e d i n t h e d e s i r e d s t a r t i n g m a t e r i a l s 7 4 a , b a s s e e n i n S c h e m e 1 9 . A n a l t e r n a t i v e p r o c e d u r e t o s y n t h e s i z e t h e m e t h y l c o m p o u n d 7 4 a a n d some o t h e r s i m i l a r d e r i v a t i v e s h a s r e c e n t l y b e e n r e p o r t e d b y Z i m m e r m a n a n d c o - w o r k e r s . S c h e m e 19 S y n t h e s i s o f 4 , 4 - D i p h e n y l - 6 - m e t h y l c y c l o h e x e n o n e ( 7 4 a ) a n d 4 , 4 - D i p h e n y l - 6 - e t h y l c y c l o h e x e n o n e ( 7 4 b ) . 4 0 -B . S y n t h e s i s o f 9 - S u b s t i t u t e d 9 , 1 0 - E t h e n o a n t h r a c e n e S u b s t r a t e s 5 8 A [4+2] c y c l o a d d i t i o n r e a c t i o n ( D i e l s - A l d e r ) b e t w e e n t h e a p p r o p r i a t e 9 - s u b s t i t u t e d a n t h r a c e n e a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e o r m e t h y l p r o p y n o a t e a f f o r d e d e a c h i n d i v i d u a l s t a r t i n g m a t e r i a l . Some o f t h e 9 - s u b s t i t u t e d a n t h r a c e n e s w e r e p r e p a r e d a c c o r d i n g t o t h e k n o w n m e t h o d s ( S c h e m e 2 0 ) ; o t h e r s a r e c o m m e r c i a l l y a v a i l a b l e . 9-A n t h r a c e n e m e t h a n o l a c e t a t e ( 8 7 ) was p r e p a r e d b y t r e a t m e n t o f 9-a n t h r a c e n e m e t h a n o l ( 8 6 ) w i t h a c e t y l c h l o r i d e . O t h e r 9 - a n t h r a c e n e m e t h a n o l d e r i v a t i v e s 8 9 a - c w e r e made f r o m 9 - c h l o r o m e t h y l a n t h r a c e n e ( 8 8 ) b y t r e a t m e n t w i t h t h e c o r r e s p o n d i n g a c i d a c c o r d i n g t o t h e m e t h o d o f 59 S t e w a r t . T h e a c e t y l e n e d e r i v a t i v e 8 9 c w a s a l s o p r e p a r e d b y r e f l u x i n g 9 - a n t h r a c e n e m e t h a n o l ( 8 6 ) w i t h p r o p i o l i c a c i d i n b e n z e n e , w h i c h g a v e a h i g h e r y i e l d . a - M e t h y l 9 - a n t h r a c e n e m e t h a n o l ( 9 1 ) was r e a d i l y p r e p a r e d b y t h e r e p o r t e d p r o c e d u r e i n v o l v i n g a d d i t i o n o f m e t h y l m a g n e s i u m i o d i d e t o 9 - a n t h r a l d e h y d e ( 9 0 ) . 6 0 T h e b r i d g e h e a d s u b s t i t u t e d d i b e n z o b a r r e l e n e d i e s t e r s 9 3 a - d w e r e s y n t h e s i z e d b y D i e l s - A l d e r r e a c t i o n b e t w e e n t h e c o r r e s p o n d i n g 9-s u b s t i t u t e d a n t h r a c e n e s 8 7 - 8 9 a , b a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( 9 2 ) ( S c h e m e 2 1 ) . A m i l d r e d u c t i o n o f c o m p o u n d 9 4 , w h i c h i s p r e p a r e d b y D i e l s - A l d e r r e a c t i o n , w i t h N a B H 4 a t l o w t e m p e r a t u r e was u s e d t o p r e p a r e 9 - h y d r o x y m e t h y l 9 , 1 0 - e t h e n o a n t h r a c e n e d i e s t e r 9 5 . I n i t i a l a t t e m p t s t o o b t a i n t h i s s t a r t i n g m a t e r i a l b y t h e d i r e c t [4+2] c y c l o a d d i t i o n o f 9-a n t h r a c e n e m e t h a n o l ( 8 6 ) t o d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e f a i l e d . - 41 88 89a-c a. R = ( ± ) - or (R)-(-)CH(OMe)Ph b. R = ( ± ) - or (S)-(-)CH(Me)NHC0CH3 c. R = C=CH Scheme 20 P r e p a r a t i o n of 9 -Subs t i t u t ed Anthracenes . - 42 -87, 88, 89a-b 92 93 a . R - ( ± ) - o r ( R ) - ( - ) - O C O C H ( O M e ) P h b . R = ( ± ) - o r ( S ) - ( - ) - 0 C 0 C H ( M e ) N H C 0 C H 3 c . R = 0C0CH3 d . R = CI C02Me CH20H 95 Scheme 21 P r e p a r a t i o n o f B r i d g e h e a d S u b s t i t u t e d D i b e n z o b a r r e l e n e Compounds via D i e l s - A l d e r R e a c t i o n . The d i r e c t r e a c t i o n between a l c o h o l 86 and t h e a c e t y l e n i c d i e n o p h i l e 92 a f f o r d e d l a c t o n e - e s t e r 96 i n s t e a d . I t i s b e l i e v e d t h a t the l a c t o n e - e s t e r 96 was d e r i v e d from the c o r r e s p o n d i n g a l c o h o l d e r i v a t i v e - 43 95 by the elimination of methanol under the high temperature r e a c t i o n conditions employed (Scheme 22). This was confirmed by a GC analysis (oven temperature = 220°C) of the authentic sample 95, which gave sin g l e peak with the same retention time as that of compound 96. Since the lactone-ester 96 showed i n t e r e s t i n g photochemical behavior both i n s o l u t i o n and i n the s o l i d state, the methyl substituted analogue 97 was designed and synthesized by the s i m i l a r procedure of heating a mixture of anthracene 91 and dimethyl acetylenedicarboxylate (Scheme 22). Scheme 22 Preparation of Lactone-Ester 96 and Methyl Lactone-Ester 97. - 44 -i A l t h o u g h t h e s y n t h e s i s o f t h e d i b e n z o b a r r e l e n e d i e s t e r s w i t h c h i r a l s u b s t i t u e n t s a t t h e 9 - p o s i t i o n , c o m p o u n d s 93a a n d 93b, w a s f i r s t a t t e m p t e d b y e s t e r i f i c a t i o n o f t h e c o r r e s p o n d i n g a c i d c h l o r i d e s w i t h t h e a l c o h o l d e r i v a t i v e 95 ( S c h e m e 23), t h e a p p r o a c h w a s u n s u c c e s s f u l o w i n g t o p o o r y i e l d s . C02Me 93b was n o t i s o l a t e d 95 + ( ± ) - P h C H ( O M e ) C O C l • 93a l o w y i e l d S c h e m e 23 E s t e r i f i c a t i o n s b e t w e e n A l c o h o l 95 a n d t h e C o r r e s p o n d i n g A c i d C h l o r i d e s . S c h e m e 24 s h o w s t h e p r e p a r a t i o n o f t h e f i v e - m e m b e r e d r i n g l a c t o n e 98 w h i c h was a c c o m p l i s h e d b y a n i n t r a m o l e c u l a r D i e l s - A l d e r r e a c t i o n o f 9 - a n t h r y l m e t h y l p r o p y n o a t e ( 8 9 c ) . 9 - S u b s t i t u t e d d i b e n z o b a r r e l e n e v i n y l raonoesters 99 a n d 1 0 0 w e r e made f r o m t h e c o r r e s p o n d i n g a n t h r a c e n e 8 9 a a n d m e t h y l p r o p y n o a t e ( S c h e m e 24). D i e l s - A l d e r r e a c t i o n b e t w e e n t h e two - 45 c o m p o u n d s g a v e a 1:1 m i x t u r e o f t h e h e a d - t o - h e a d a n d t h e h e a d - t o - t a i l i s o m e r s . ^ T h e s e two i s o m e r s w e r e s e p a r a t e d b y c o l u m n c h r o m a t o g r a p h y a n d w e r e d i s t i n g u i s h a b l e f r o m o n e a n o t h e r b y t h e c o u p l i n g c o n s t a n t s b e t w e e n t h e b r i d g e h e a d a n d v i n y l p r o t o n s . T h e a s s i g n m e n t w a s b a s e d o n t h e d i f f e r e n c e i n t h e m a g n i t u d e o f t h i s c o u p l i n g , w h i c h i s e i t h e r v i c i n a l c o u p l i n g ( J = 6 Hz) i n c o m p o u n d 100 o r f o u r - b o n d c o u p l i n g (J = 1 Hz) i n c o m p o u n d 99 ( F i g u r e 3 ) . T h e l i n e b r o a d e n i n g o f t h e s i g n a l s i n t h e H^ NMR s p e c t r u m o f c o m p o u n d 100 i s p r o b a b l y d u e t o t h e i n t e r a c t i o n s b e t w e e n t h e t w o s i d e c h a i n s , a s t h e s i g n a l s s h a r p e n e d w h e n t h e t e m p e r a t u r e was i n c r e a s e d . I n c o n t r a s t , t h e r e i s n o s u c h c o n t a c t p r e s e n t i n t h e i s o m e r 99, a n d n o l i n e b r o a d e n i n g w a s o b s e r v e d . T h i s f u r t h e r s u p p o r t s t h e s t r u c t u r a l a s s i g n m e n t s . S c h e m e 24 S y n t h e s i s o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e M o n o e s t e r s . - 46 -CO 2 Me - 1 r— l 1 r—| 1 1—1 1 j i—I—i—I 1 1—I ' I ' I 1 1 i—1 r 8 7 6 5 4 ppm Figure 3 Partial H NMR Spectra of Dibenzobarrelenes 99 and 100. - 47 -A l l s t r u c t u r e s o f t h e d i b e n z o b a r r e l e n e c o m p o u n d s w e r e e s t a b l i s h e d b y a n a l y t i c a l a n d s p e c t r o s c o p i c m e t h o d s a n d a l s o b y X - r a y c r y s t a l s t r u c t u r e a n a l y s e s i n s o m e c a s e s . C . P r e p a r a t i o n o f C r y s t a l l i n e S a m p l e s E x c e p t f o r t h e c a s e o f c y c l o h e x e n o n e 7 4 b , w h i c h p r o v e d t o b e a n o i l a t r o o m t e m p e r a t u r e , a l l o f t h e s t a r t i n g m a t e r i a l s w e r e o b t a i n e d i n c r y s t a l l i n e f o r m b y r e c r y s t a l l i z a t i o n f r o m s u i t a b l e s o l v e n t ( s ) . M o s t o f t h e c r y s t a l l i n e s a m p l e s h a v e r e l a t i v e l y h i g h m e l t i n g p o i n t s ( T a b l e 1 ) , a n d t h i s f a c i l i t a t e s t h e p h o t o c h e m i c a l s t u d i e s o f t h e s e c o m p o u n d s i n t h e s o l i d s t a t e . T a b l e 1 S u m m a r y o f C r y s t a l P r e p a r a t i o n s . C o m p o u n d C r y s t a l l i z a t i o n S o l v e n t M e l t i n g P o i n t ( ° C ) C y c l o h e x e n o n e 7 1 a e t h e r / p e t r o l e u m e t h e r 1 2 3 - 1 2 4 C y c l o h e x e n o n e 7 1 b d i e t h y l e t h e r 7 9 - 8 0 C y c l o h e x e n o n e 7 4 a m e t h y l c y c l o h e x a n e 9 9 - 1 0 0 D i b e n z o b a r r e l e n e 94 b e n z e n e 1 7 1 - 1 7 3 D i b e n z o b a r r e l e n e 95 m e t h a n o l 1 7 4 - 1 7 6 D i b e n z o b a r r e l e n e 9 3 c a c e t o n e / h e x a n e 1 6 2 - 1 6 3 L a c t o n e - E s t e r 96 m e t h a n o l / c h l o r o f o r m 1 7 1 - 1 7 2 ( t o b e c o n t i n u e d ) 48 ( c o n t i n u e d f r o m P a g e 4 7 ) M e t h y l L a c t o n e - E s t e r 97 m e t h a n o l / m e t h y l e n e c h l o r i d e 1 9 1 - 192 D i b e n z o b a r r e l e n e 9 3 d me t h a n o 1 / c h l o r o f o r m 1 6 8 - 1 7 0 ( ± ) - D i b e n z o b a r r e l e n e 9 3 b a c e t o n e / h e x a n e 1 1 0 - 112 ( S ) - ( + ) - D i b e n z o b a r r e l e n e 93b a c e t o n e / h e x a n e 1 7 8 - 1 8 0 ( ± ) - D i b e n z o b a r r e l e n e 9 3 a a c e t o n e / h e x a n e 1 4 1 - 142 ( R ) - ( - ) - D i b e n z o b a r r e l e n e 9 3 a a c e t o n e / h e x a n e 1 4 1 - 143 ( ± ) - M o n o e s t e r 99 e t h y l a c e t a t e / p e t r o l e u m e t h e r 1 9 4 - 195 ( R ) - ( - ) - M o n o e s t e r 99 e t h e r / p e t r o l e u m e t h e r 1 8 2 - 183 ( ± ) - M o n o e s t e r 100 e t h y l a c e t a t e / p e t r o l e u m e t h e r 1 3 7 - 139 ( R ) - ( - ) - M o n o e s t e r 100 e t h e r / p e t r o l e u m e t h e r 1 5 6 - 158 I n o r d e r t o s t u d y t h e i n f l u e n c e o f c r y s t a l m o r p h o l o g y o n p h o t o r e a c t i v i t y , e a c h c o m p o u n d was r e c r y s t a l l i z e d f r o m d i f f e r e n t o r g a n i c s o l v e n t s o r s o l v e n t m i x t u r e s . I n some c a s e s , r e c r y s t a l l i z a t i o n f r o m m e l t was a l s o c a r r i e d o u t . I n t h e c a s e o f c o m p o u n d 9 3 d , c r y s t a l m o d i f i c a t i o n w a s s u c c e s s f u l l y a c h i e v e d . T h i s w i l l b e d i s c u s s e d i n d e t a i l i n t h e l a t t e r p a r t o f t h e t h e s i s . I I . S t u d i e s o n 4 , 4 - D i a r y l c y c l o h e x e n o n e s A . P h o t o r e a r r a n g e m e n t o f 4 - P h e n y l - 4 - a r y l c y c l o h e x e n o n e s - 49 -T h e s o l u t i o n s t a t e p h o t o c h e m i s t r y o f 4 , 4 - d i p h e n y l c y c l o h e x e n o n e ( 3 6 a ) , 4 , 4 - d i b i p h e n y l c y c l o h e x e n o n e ( 3 6 b ) a n d 4 , 4 - d i - o - n a p h t h y l -c y c l o h e x e n o n e ( 3 6 c ) h a s p r e v i o u s l y b e e n s t u d i e d b y Z i m m e r m a n a n d c o -w o r k e r s . ' ' ' U p o n i r r a d i a t i o n i n s o l u t i o n , t h e d i a r y l s u b s t i t u t e d e n o n e s w e r e s h o w n t o f o r m t h e c o r r e s p o n d i n g b i c y c l o [ 3 . 1 . O ] h e x a n o n e s b y m i g r a t i o n o f o n e o f t h e a r y l g r o u p s r e a c t i n g via t h e t r i p l e t e x c i t e d s t a t e . T h e m a j o r p r o d u c t i n e a c h c a s e w a s f o u n d t o h a v e t h e trans g e o m e t r y s u c h a s 3 9 a - c ( S c h e m e 2 5 ) . I f t h e c y c l o h e x e n o n e i s u n s y m m e t r i c a l l y s u b s t i t u t e d a t t h e C - ( 4 ) p o s i t i o n , i . e . t h e two a r y l g r o u p s a r e n o n - i d e n t i c a l , t h e m i g r a t i o n o f e a c h a r y l g r o u p w i l l g i v e a d i f f e r e n t p r o d u c t u p o n p h o t o l y s i s . T h e r e f o r e , i t w o u l d b e o f i n t e r e s t t o i n v e s t i g a t e t h e m i g r a t i o n a p t i t u d e i n s o l u t i o n v e r s u s t h e s o l i d s t a t e a n d t o s t u d y h o w t h e c r y s t a l l a t t i c e a f f e c t s t h e m i g r a t o r y a b i l i t y o f d i f f e r e n t a r y l g r o u p s . T h e c o m p o u n d s c h o s e n f o r t h e s e s t u d i e s a r e f o u n d i n t h e f o l l o w i n g s e c t i o n s . 0 P h -(x • (X • T -i AT Z A r T A r A r A r ~ r A r A r 36 39 4 0 1 0 1 a . A r = P h b . A r = a - n a p h t h y l c . A r - b i p h e n y l S c h e m e 25 P h o t o t r a n s f o r m a t i o n s o f 4 , 4 - D i a r y l c y c l o h e x e n o n e s . - 50 -1 . P h o t o c h e m i s t r y o f 4 - P h e n y l - 4 - p - c y a n o p h e n y l c y c l o h e x e n o n e ( 7 1 b ) a n d 4 -P h e n y 1 - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) 53 I n a n e a r l i e r s t u d y , Z i m m e r m a n , R i e k e a n d S c h e f f e r i n v e s t i g a t e d t h e m i g r a t o r y a p t i t u d e o f d i f f e r e n t a r o m a t i c g r o u p s t h a t w e r e a t t a c h e d a t t h e C - ( 4 ) p o s i t i o n o f t h e c y c l o h e x e n o n e m o i e t y i n o r d e r t o c l a r i f y t h e e l e c t r o n i c p r o p e r t i e s o f t h e e x c i t e d s t a t e . T h e y f o u n d t h a t two s u b s t r a t e s , 4 - p h e n y l - 4 - p - c y a n o p h e n y l c y c l o h e x e n o n e ( 7 1 b ) a n d 4 - p h e n y l - 4 -p - m e t h o x y p h e n y l c y c l o h e x e n o n e ( 7 1 c ) , h a d s i m i l a r m i g r a t i o n p a t t e r n s . U p o n p h o t o l y s i s , t h e s e two s u b s t r a t e s l e d t o t h e f o r m a t i o n o f c o m p o u n d s 7 2 b a n d 7 2 c a s t h e p r e d o m i n a n t p r o d u c t s b y m i g r a t i o n o f t h e para-substituted p h e n y l g r o u p s ( S c h e m e 2 6 ) . A s a r e s u l t , i t was c o n c l u d e d t h a t i r r a d i a t i o n g a v e a n e x c i t e d - s t a t e s p e c i e s ( 1 0 2 ) w h i c h was r a d i c a l - l i k e a t t h e / 3 - c a r b o n a t o m o f t h e e n o n e m o i e t y . 0 P h A r 71 102 72 73 0 + b . Ar=p - C N C e H 4 Ph c . Ar=p-MeOC6H4 103 S c h e m e 26 P h o t o r e a r r a n g e m e n t o f 4 - P h e n y l - 4 - a r y l c y c l o h e x e n o n e s . 51 -Two c o m p o u n d s , 4 - p h e n y l - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) a n d 4 -p h e n y l - 4 - p - c y a n o p h e n y l c y c l o h e x e n o n e ( 7 1 b ) , w e r e s y n t h e s i z e d i n t h i s s t u d y . I n o r d e r t o make a c o m p a r i s o n o f t h e m i g r a t o r y a p t i t u d e s i n s o l u t i o n a n d i n t h e s o l i d s t a t e , t h e s o l u t i o n p h a s e p h o t o l y s i s o f c o m p o u n d 7 1 b w a s c a r r i e d o u t u n d e r c o n d i t i o n s s i m i l a r t o t h o s e r e p o r t e d 53 b y Z i m m e r m a n ; t h e p h o t o c h e m i s t r y o f t h e p - b r o m o p h e n y l a n a l o g u e 7 1 a i n s o l u t i o n i s o r i g i n a l t o t h i s t h e s i s . I n i t i a l l y , i r r a d i a t i o n o f t h e p - c y a n o p h e n y l d e r i v a t i v e 7 1 b i n b e n z e n e w a s p e r f o r m e d b y u s i n g w a v e l e n g t h s o f A > 2 9 0 nm ( P y r e x f i l t e r ) . 53 R e s u l t s s i m i l a r t o t h o s e r e p o r t e d b y Z i m m e r m a n e t al. w e r e o b t a i n e d . I t w a s f o u n d l a t e r t h a t n o cis p h o t o p r o d u c t 1 0 3 b c o u l d b e d e t e c t e d i f t h e s a m p l e was i r r a d i a t e d w i t h w a v e l e n g t h s l o n g e r t h a n 3 4 0 run ( u s i n g a u r a n i u m g l a s s f i l t e r ) . T h e r e s u l t s o f t h e w a v e l e n g t h d e p e n d e n c y i n t h e p h o t o l y s i s o f 4 - p h e n y l - 4 - p - c y a n o p h e n y l c y c l o h e x e n o n e ( 7 1 b ) a r e s u m m a r i z e d i n T a b l e 2 . O u r i n t e r p r e t a t i o n o f t h e r e s u l t s i s t h a t t h e a b s o r p t i o n o f t h e p r i m a r y p h o t o p r o d u c t 7 2 b a t t h e l o n g e r w a v e l e n g t h s i s m i n i m a l , s o t h a t t h e s e c o n d a r y p h o t o r e a c t i o n o f 7 2 b t o g i v e 1 0 3 b i s n e g l i g i b l e u n d e r t h e s e c o n d i t i o n s . H o w e v e r , s u c h i n t e r c o n v e r s i o n o f t h e p h o t o p r o d u c t s i s s i g n i f i c a n t u n d e r t h e c o n d i t i o n o f A > 2 9 0 nm i r r a d i a t i o n . T a b l e 2 P h o t o l y s i s o f 4 - P h e n y l - 4 - p - c y a n o p h e n y l c y c l o h e x e n o n e a t D i f f e r e n t I r r a d i a t i o n W a v e l e n g t h s . a C o n d i t i o n C o n v e r s i o n P e r c e n t a g e Y i e l d R a t i o A > (nm) (%) 72b (%) 103b (%) 73b (%) (72b+103b)/73b 2 9 0 nm 9 1 71 13 7 12 ± l b 3 4 0 nm 99 91 0 8 11 ± 1 a b A n a l y s i s b y g a s c h r o m a t o g r a p h y . T h e r e s u l t s o b t a i n e d i n t h i s s t u d y a r e t h e s a m e a s t h o s e r e p o r t e d ( r a t i o = 14 ± 2 . 5 ) b y Z i m m e r m a n et al. , s e e r e f e r e n c e 5 3 . P h o t o l y s i s o f 4 - p h e n y l - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) . was c o n d u c t e d i n s o l u t i o n ( b e n z e n e o r a c e t o n e ) b y u s i n g w a v e l e n g t h s l o n g e r t h a n 3 4 0 n m . Two i s o m e r i c p h o t o p r o d u c t s w e r e i s o l a t e d i n a p r e p a r a t i v e r u n a n d c h a r a c t e r i z e d a s t h e b i c y c l i c k e t o n e s 7 2 a a n d 7 3 a ( S c h e m e 26 ) . T h e s t r u c t u r a l a s s i g n m e n t s a r e b a s e d o n s p e c t r o s c o p i c i n f o r m a t i o n a n d o n 5 3 t h e c o n v e r s i o n o f e a c h p h o t o p r o d u c t t o t h e k n o w n b i c y c l i c c y a n o d e r i v a t i v e 7 2 b o r 7 3 b ( S c h e m e 2 7 ) . T h e trans g e o m e t r y o f t h e two a r o m a t i c g r o u p s o n t h e t h r e e - m e m b e r e d r i n g i s c h a r a c t e r i z e d b y t h e c o u p l i n g c o n s t a n t o f 10 H z , w h i c h i s a t t r i b u t e d t o cis-cyclopropyl C H -C H c o u p l i n g . • * I n t h e c a s e o f t h e b i c y c l i c k e t o n e 7 2 a , t h e s t r u c t u r e w a s a l s o c o n f i r m e d b y a n X - r a y c r y s t a l l o g r a p h i c a n a l y s i s . T h i s w o r k was d o n e b y M s . C h r i s t i n e H w a n g , a n d t h e s t r u c t u r a l d e t a i l s h a v e b e e n d o c u m e n t e d i n h e r t h e s i s . ^ T h e s t e r e o d i a g r a m o f t h e m o l e c u l e , - 53 -t r a n s - 5 - p h e n y l - 6 - p - b r o m o p h e n y l b i c y c l o [ 3 . 1 . 0 ] h e x a n - 2 - o n e ( 7 2 a ) , i s g i v e n i n F i g u r e 4 . 0 (X -£ P h B r - p C u C N P h 72c a. C u C N ' P h P h B r - p 7 3 a 0 P h C N - p P h 0 7 2 b P h P h C N - p 7 3 b S c h e m e 27 C o n v e r s i o n o f P h o t o p r o d u c t s 7 2 a a n d 7 3 a t o t h e K n o w n C y a n o D e r i v a t i v e s 7 2 b a n d 7 3 b . F i g u r e 4 S t e r e o d i a g r a m o f t h e M o l e c u l e o f trans - 5 - P h e n y l - 6 - p -b r o m o p h e n y l b i c y c l o [ 3 . 1 . 0 ] h e x a n - 2 - o n e ( 7 2 a ) . 54 I t w a s a l s o f o u n d t h a t t h e p h o t o p r o d u c t 7 2 a w a s t h e m a j o r o n e i n t h e p h o t o l y s i s o f 7 1 a . T h e p r o d u c t r a t i o 7 2 a / 7 3 a , w h i c h i s s u m m a r i z e d i n T a b l e 3 , w a s f o u n d t o b e c o n s t a n t u n d e r d i f f e r e n t p e r c e n t a g e c o n v e r s i o n s o f t h e s t a r t i n g m a t e r i a l . T h i s r a t i o r e p r e s e n t s t h e r e l a t i v e m i g r a t o r y a b i l i t y o f t h e two a r o m a t i c g r o u p s i n t h e s o l u t i o n p h a s e . T a b l e 3 P h o t o l y s i s o f 4 - P h e n y l - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) i n B e n z e n e u n d e r V a r y i n g C o n v e r s i o n s . 3 C o n v e r s i o n (%) Y i e l d R a t i o o f 7 1 a 7 2 a (%) 7 3 a (%) 7 2 a : 7 3 a 16 11 5 69:31 25 17 7 71:29 41 28 13 68:32 54 39 17 72:28 84 57 27 68:32 1 A n a l y s i s b y g a s c h r o m a t o g r a p h y . T h e p r e f e r e n c e f o r t h e p - b r o m o p h e n y l g r o u p m i g r a t i o n l e a d i n g t o p h o t o p r o d u c t 7 2 a c a n b e u n d e r s t o o d b y a p p l y i n g t h e s a m e m e c h a n i s m w h i c h w a s p r o p o s e d b y Z i m m e r m a n a n d c o - w o r k e r s ' n e a r l y t w o d e c a d e s a g o . Z i m m e r m a n et al. s u g g e s t e d t h a t t h e m i g r a t i o n o f t h e a r o m a t i c g r o u p s o c c u r s t h r o u g h t h e h a l f - m i g r a t e d s p e c i e s 1 0 4 a n d 105 f r o m t h e e x c i t e d s t a t e i n t e r m e d i a t e 102 ( S c h e m e 28 ) . I t i s a p p a r e n t t h a t t h e b i r a d i c a l 55 s p e c i e s 104 w o u l d b e m o r e s t a b i l i z e d b y t h e para-substituents ( X = B r , CN and. OMe) t h r o u g h r e s o n a n c e t h a n t h e b i r a d i c a l 1 0 5 . T h e r e f o r e , t h e a r y l g r o u p m i g r a t e s p r e f e r e n t i a l l y . We n o t e , h o w e v e r , t h a t t h e m i g r a t o r y p r e f e r e n c e o f t h e p a r a - b r o m o p h e n y l g r o u p i s l e s s t h a n t h a t o f t h e para-53 c y a n o 7 1 b ( m i g r a t i o n r a t i o o f a r y l : p h e n y l = 14 ± 2 . 5 ) o r t h e para-53 m e t h o x y d e r i v a t i v e s 7 1 c ( m i g r a t i o n r a t i o o f a r y l : p h e n y l = 12 ± 2 . 5 ) . S c h e m e 28 M e c h a n i s t i c P r e s e n t a t i o n o f t h e P h o t o r e a r r a n g e m e n t o f 4 -P h e n y l - 4 - a r y l c y c l o h e x e n o n e s . 2 . M i g r a t o r y A p t i t u d e i n t h e S o l i d S t a t e I n t h e i r v e r y r e c e n t s t u d i e s , Z i m m e r m a n a n d c o - w o r k e r s ^ h a v e r e p o r t e d t h e s o l i d s t a t e p h o t o c h e m i c a l b e h a v i o r o f c o m p o u n d s 3 6 a - c ( S c h e m e 2 5 ) . T h e y f o u n d t h a t t h e p h o t o c h e m i s t r y o f t h e s e c o m p o u n d s i n 56 -s o l i d s t a t e i s q u i t e s i m i l a r t o t h a t i n s o l u t i o n . I n e a c h c a s e , t h e m a j o r s o l i d s t a t e p h o t o p r o d u c t w a s t h e trans-diarylbicyclic k e t o n e 3 9 . H o w e v e r , i t was f o u n d t h a t t h e e f f i c i e n c y o f t h e s o l i d s t a t e r e a c t i o n i n t e r m s o f q u a n t u m y i e l d s w a s m u c h l o w e r t h a n t h a t i n s o l u t i o n . W h e n c r y s t a l s o r p o w d e r s o f t h e p - c y a n o p h e n y l d e r i v a t i v e 7 1 b w e r e i r r a d i a t e d a t r o o m t e m p e r a t u r e , t h e r e a c t i o n w a s f o u n d t o g i v e t h e s a m e p h o t o p r o d u c t s a s i n t h e s o l u t i o n p h a s e r e a c t i o n . B u t , t h e p r o d u c t d i s t r i b u t i o n , i . e . t h e r a t i o ( 7 2 b + 1 0 3 b ) / 7 3 b , i n t h e s o l i d s t a t e was f o u n d t o b e q u i t e d i f f e r e n t f r o m t h a t i n s o l u t i o n . I n t h e s o l i d s t a t e , a l t h o u g h p - c y a n o p h e n y l m i g r a t i o n p r o d u c t 7 2 b w a s s t i l l p r e d o m i n a n t , t h e f o r m a t i o n o f t h e p h e n y l g r o u p m i g r a t i o n p r o d u c t 7 3 b was i n c r e a s e d c o m p a r e d t o t h e v a l u e i n b e n z e n e ( T a b l e 4) . A s t h e s o l i d s t a t e p h o t o r e a c t i o n o f 7 1 b r e s u l t e d i n p a r t i a l m e l t i n g o f t h e c r y s t a l l i n e s a m p l e s a t h i g h c o n v e r s i o n s o f t h e s t a r t i n g m a t e r i a l , t h e r e a c t i o n was n o r m a l l y k e p t w i t h i n 10-20% c o n v e r s i o n i n o r d e r t o m i n i m i z e t h e c r y s t a l m e l t i n g . S i m i l a r l y , 4 - p h e n y l - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) g a v e t h e two c o r r e s p o n d i n g b i c y c l i c k e t o n e s 7 2 a a n d 7 3 a u p o n p h o t o l y s i s i n t h e s o l i d s t a t e . I t was o b s e r v e d t h a t t h e r e a c t i o n o f 7 1 a i n t h e s o l i d s t a t e w a s i n e f f i c i e n t . No m o r e t h a n 2% c o n v e r s i o n o f t h e s t a r t i n g m a t e r i a l c o u l d b e a c h i e v e d e v e n f o r a l o n g p e r i o d o f i r r a d i a t i o n ( u p t o 48 h r ) b y u s i n g p o w d e r e d s a m p l e s o f 7 1 a . T h e p r o d u c t r a t i o 7 2 a / 7 3 a was a l s o f o u n d t o b e d i f f e r e n t f r o m t h a t i n s o l u t i o n a n d i t i s i n c l u d e d i n T a b l e 4. S i n g l e c r y s t a l s o f 7 1 a w e r e f o u n d t o b e p h o t o c h e m i c a l l y u n r e a c t i v e ( w i t h i n d e t e c t i o n l i m i t s ) . - 57 -T a b l e 4 M i g r a t o r y S e l e c t i v i t y o f 4 - p - C y a n o p h e n y l - a n d 4 - p -B r o m o p h e n y l - 4 - p h e n y l c y c l o h e x e n o n e s i n S o l u t i o n a n d i n t h e S o l i d S t a t e . 3 C o m p o u n d M e d i u m C o n v e r s i o n M i g r a t i o n R a t i o (%) (72b+103b)/73b 72a/73a C y a n o 7 1 b S o l u t i o n 99 11 + 1 C y a n o 7 1 b C r y s t a l 20 2 . 2 + 0 . 2 b C y a n o 7 1 b C r y s t a l 4 0 3 . 1 + 0 . 3 C B r o m o 7 1 a S o l u t i o n 16 2 . 4 ± 0 . 2 B r o m o 7 1 a C r y s t a l 2 1 . 5 ± 0 . 2 A n a l y s i s b y g a s c h r o m a t o g r a p h y . I r r a d i a t i o n a t 337 nm b y u s i n g a n i t r o g e n l a s e r . ° I r r a d i a t i o n a t 337 nm b y u s i n g a n i t r o g e n l a s e r , p a r t i a l c r y s t a l m e l t i n g w a s o b s e r v e d . A c o m p a r i s o n o f t h e p r o d u c t d i s t r i b u t i o n s i n t h e c r y s t a l l i n e a n d s o l u t i o n p h a s e s r e v e a l s t h a t , f o r b o t h s u b s t r a t e s 7 1 a a n d 7 1 b , a r y l g r o u p m i g r a t i o n ( p - c y a n o p h e n y l o r p - b r o m o p h e n y l ) i s p r e d o m i n a n t i n b o t h m e d i a . H o w e v e r , t h e p h o t o l y s i s i n t h e s o l i d s t a t e i n c r e a s e s t h e a m o u n t o f t h e p h e n y l g r o u p m i g r a t i o n p r o d u c t . T h e m e d i u m e f f e c t o n t h e m i g r a t o r y a p t i t u d e i s s i g n i f i c a n t i n t h e p h o t o l y s i s o f c o m p o u n d 7 1 b , i n w h i c h t h e m i g r a t i o n r a t i o ( A r : P h ) c h a n g e s f r o m 11 ± 1 i n b e n z e n e t o 2 . 2 ± 0 . 2 i n t h e s o l i d s t a t e . T h e r e s u l t s f o r b o t h c o m p o u n d s , 7 1 a a n d 7 1 b , s e e m t o b e i n a g r e e m e n t w i t h o u r i n i t i a l i d e a s t h a t a r y l g r o u p s ( p -- 58 -b r o m o p h e n y l a n d p - c y a n o p h e n y l ) m i g h t n o t m i g r a t e s o w e l l i n t h e s o l i d s t a t e o w i n g t o t h e i r l a r g e r s i z e s . G e n e r a l l y s p e a k i n g , t h e p - c y a n o p h e n y l o r p - b r o m o p h e n y l g r o u p i s l a r g e r i n s i z e t h a n t h e p h e n y l g r o u p , a l t h o u g h t h e d i f f e r e n c e b e t w e e n t h e m i s s m a l l . T h e m i g r a t i o n o f t h e p a r a -s u b s t i t u t e d p h e n y l g r o u p l e a d i n g t o t h e m a j o r p h o t o p r o d u c t s 7 2 a a n d 7 2 b , w h i c h i s f a v o r e d i n s o l u t i o n b y t h e e l e c t r o n i c e f f e c t , may i n v o l v e m o r e a t o m i c a n d m o l e c u l a r m o t i o n s o v e r a l l i n t h e s o l i d s t a t e r e a c t i o n . T h e r e f o r e , m o r e i n t e r f e r e n c e b e t w e e n t h e r e a c t i n g m o l e c u l e a n d t h e c r y s t a l l a t t i c e w o u l d b e e x p e c t e d . S u c h a r e a c t i o n p a t h w a y t h a t r e s u l t s i n m o r e d i s t u r b a n c e o f t h e c r y s t a l l a t t i c e m i g h t b e r e s t r a i n e d b y t h e l a t t i c e . O n t h e o t h e r h a n d , f o r m a t i o n o f t h e b i c y c l i c k e t o n e s 7 3 a a n d 7 3 b i s m o r e f a v o r a b l e d u e t o r e d u c e d i n t e r f e r e n c e w i t h t h e c r y s t a l l a t t i c e b y t h e m i g r a t i o n o f t h e p h e n y l g r o u p . A l t h o u g h s u c h a s p e c u l a t i o n s e e m s r e a s o n a b l e , f u r t h e r e v i d e n c e t o s u p p o r t t h i s i s n e e d e d f r o m t h e p o i n t o f v i e w o f a m o l e c u l a r c r y s t a l s t r u c t u r e a n a l y s i s . O w i n g t o t h e p o o r q u a l i t y o f t h e c r y s t a l s o b t a i n e d f o r c o m p o u n d 7 1 b , t h e m o l e c u l a r c r y s t a l s t r u c t u r e o f 7 1 b h a s n o t b e e n d e t e r m i n e d y e t . I n t h e c a s e o f c o m p o u n d 7 1 a , h o w e v e r , t h e m o l e c u l a r c r y s t a l s t r u c t u r e h a s b e e n d e t e r m i n e d . T h e o b s e r v e d 1-2% r e a c t i o n b y u s i n g p o w d e r s o f 7 1 a c o u l d b e a s c r i b e d t o a s u r f a c e p h o t o r e a c t i o n . I t CO h a s b e e n r e p o r t e d r e c e n t l y b y S c h e f f e r , T r o t t e r a n d c o - w o r k e r s t h a t r e a c t i o n o c c u r r i n g o n t h e s u r f a c e o f c e r t a i n c r y s t a l s g i v e s l o w e r s e l e c t i v i t y c o m p a r e d t o t h a t i n t h e b u l k . I n t h e f o l l o w i n g s e c t i o n , p o s s i b l e r e a s o n s f o r t h e l a c k o f r e a c t i v i t y o f e n o n e 7 1 a i n t h e b u l k a r e d i s c u s s e d . - 59 -3 . M o l e c u l a r C r y s t a l S t r u c t u r e o f 4 - P h e n y l - 4 - p - b r o m o p h e n y l c y c l o h e x e n o n e ( 7 1 a ) a n d I t s P h o t o c h e m i c a l I m p l i c a t i o n s T h e s t e r e o d i a g r a m o f t h e m o l e c u l e 7 1 a i s f o u n d i n F i g u r e 5, a n d t h e c r y s t a l p a c k i n g d i a g r a m g i v i n g t h e r e l a t i v e p o s i t i o n s o f t h e m o l e c u l e s i n a u n i t c e l l i s p r e s e n t e d i n F i g u r e 6 . F r o m t h e c r y s t a l s t r u c t u r e a n a l y s i s , i t w a s f o u n d t h a t t h e p -b r o m o p h e n y l g r o u p i s s i t u a t e d i n a p s e u d o - a x i a l p o s i t i o n o n t h e c y c l o h e x e n o n e r i n g , w h e r e a s t h e p h e n y l g r o u p l i e s i n a p s e u d o - e q u a t o r i a l p o s i t i o n . B a s e d o n t h e e s t a b l i s h e d p r i n c i p l e s i n s o l i d s t a t e c h e m i s t r y , we a s s u m e t h a t t h e l a c k o f p h o t o r e a c t i v i t y f o r c o m p o u n d 7 1 a i n t h e s o l i d s t a t e ( b u l k ) m i g h t b e d u e t o a p a r t i c u l a r c o n f o r m a t i o n t h a t t h e c y c l o h e x e n o n e 7 1 a a d o p t s a n d / o r t h e s p e c i f i c p a c k i n g a r r a n g e m e n t o f t h e r e a c t i n g m o l e c u l e s i n t h e c r y s t a l , w h i c h p e r h a p s p r e v e n t s t h e a r o m a t i c g r o u p s f r o m m i g r a t i n g . F i g u r e 5 S t e r e o d i a g r a m o f C y c l o h e x e n o n e 7 1 a w i t h D i s o r d e r . 60 -F i g u r e 6 C r y s t a l P a c k i n g D i a g r a m o f C y c l o h e x e n o n e 71a. F r o m t h e p a c k i n g d i a g r a m ( F i g u r e 6) , i t c a n b e n o t e d t h a t t h e p h e n y l g r o u p o f o n e e n o n e m o l e c u l e i s c l o s e l y p a c k e d w i t h a n e i g h b o r i n g m o l e c u l e o n t h e s i d e t h a t m i g r a t i o n o f t h e p h e n y l g r o u p f r o m C - ( 4 ) t o C -( 3 ) i s e x p e c t e d . T h u s , i f t h e p h e n y l g r o u p m i g r a t e s ( m o v i n g t o w a r d s t h e o t h e r c l o s e l y p a c k e d m o l e c u l e ) , i t w o u l d b e l i k e l y t o c a u s e s e v e r e s t e r i c i n t e r a c t i o n s b e t w e e n t h e p h e n y l g r o u p a n d t h e n e i g h b o r i n g m o l e c u l e . I t i s u n d e r s t o o d t h a t s u c h a r e a c t i o n p r o c e s s w i l l b e t o p o c h e m i c a l l y u n f a v o r a b l e . O w i n g t o t h i s , we s u g g e s t t h a t p h e n y l m i g r a t i o n o f 71a i n t h e c r y s t a l m i g h t b e i m p o s s i b l e o r a t l e a s t i n e f f i c i e n t . 61 -O n t h e o t h e r h a n d , t h e p s e u d o - a x i a l para-bromophenyl g r o u p i s f r e e o f a n y s p e c i f i c i n t e r m o l e c u l a r c o n t a c t s o t h a t p a r a - b r o m o p h e n y l m i g r a t i o n l e a d i n g t o p h o t o p r o d u c t 72a w o u l d b e e x p e c t e d t o p r o c e e d u p o n p h o t o l y s i s o f 71a i n t h e s o l i d s t a t e . I n f a c t , t h e f o r m a t i o n o f p h o t o p r o d u c t 72a was i n s i g n i f i c a n t w h e n t h e b u l k c r y s t a l s o f 71a w e r e i r r a d i a t e d . O n e p o s s i b i l i t y t h a t m i g h t b e t a k e n f r o m t h e c r y s t a l s t r u c t u r e a n a l y s i s s e e m s t o s u g g e s t t h a t t h e o r i e n t a t i o n o f t h e p -b r o m o p h e n y l g r o u p i s u n f a v o r a b l e f o r t h e m i g r a t i o n . I t i s w e l l u n d e r s t o o d t h a t , f o r a 1 , 2 - s h i f t o r m i g r a t i o n o f a p h e n y l g r o u p , t h e p l a n e o f t h e a r o m a t i c r i n g s h o u l d b e p e r p e n d i c u l a r t o t h e C ( l ) - C ( 2 ) b o n d ( S c h e m e 2 9 ) i n o r d e r t o a c h i e v e a m a x i m u m o r b i t a l o v e r l a p . S u c h p e r p e n d i c u l a r o r i e n t a t i o n o f t h e a r o m a t i c g r o u p i s a l s o r e t a i n e d i n t h e h a l f - m i g r a t e d s p e c i e s (107). A s d e p i c t e d i n S c h e m e 28, i n o r d e r f o r t h e a r y l g r o u p t o m i g r a t e , t h e p l a n e o f t h e p a r a - s u b s t i t u t e d a r o m a t i c . r i n g s h o u l d b e o r i e n t a t e d i n a p e r p e n d i c u l a r p o s i t i o n w i t h r e s p e c t t o t h e C ( 3 ) - C ( 4 ) b o n d o f t h e e n o n e m o i e t y . H o w e v e r , i t c a n b e v i s u a l i z e d f r o m t h e m o l e c u l a r s t e r e o d i a g r a m ( F i g u r e 5 ) t h a t t h e p - b r o m o p h e n y l g r o u p i s n o t o r i e n t a t e d i n t h e i d e a l p o s i t i o n t o a l l o w m a x i m u m p - o r b i t a l o v e r l a p f o r t h e m i g r a t i o n . I n o r d e r t o d o s o , t h e p l a n e o f t h e a r o m a t i c r i n g s h o u l d b e r o t a t e d b y n e a r l y 9 0 ° . B u t s u c h r o t a t i o n m i g h t b e s t e r i c a l l y h i n d e r e d b y t h e a d j a c e n t p h e n y l g r o u p i n t h e s o l i d s t a t e . M o l e c u l a r m o d e l s o f t h e s o l i d s t a t e e n o n e c o n f o r m a t i o n s h o w t h a t t h e r o t a t i o n o f t h e p a r a - b r o m o p h e n y l g r o u p c o u l d r e s u l t i n s e v e r e s t e r i c i n t e r a c t i o n s b e t w e e n t h e ortho h y d r o g e n a t o m s ( H a a n d H^) f r o m t h e two a r o m a t i c g r o u p s ( S c h e m e 30). T h i s i n t r a m o l e c u l a r s t e r i c a r g u m e n t m i g h t e x p l a i n w h y t h e c r y s t a l o f 71a i s p h o t o c h e m i c a l l y i n e r t . S c h e m e 30 S t e r i c H i n d r a n c e o n t h e R o t a t i o n o f t h e p - B r o m o p h e n y l G r o u p i n t h e B u l k C r y s t a l s . 63 B . P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i p h e n y l - 6 - a l k y l c y c l o h e x e n o n e s 1 . P h o t o c h e m i s t r y I n f u r t h e r i n v e s t i g a t i o n s o f t h e c r y s t a l l i n e l a t t i c e e f f e c t o n t h e p h o t o c h e m i s t r y o f c y c l o h e x e n o n e c o m p o u n d s , t h e C - 6 s u b s t i t u t e d d i p h e n y l c y c l o h e x e n o n e s ( 7 4 a , b ) w e r e s y n t h e s i z e d ( S c h e m e 1 9 ) , a n d t h e i r p h o t o c h e m i s t r y was s t u d i e d . I r r a d i a t i o n o f 4 , 4 - d i p h e n y l - 6 - m e t h y l c y c l o h e x e n o n e ( 7 4 a ) was c o n d u c t e d i n t h e c r y s t a l l i n e p h a s e a n d i n s o l u t i o n a s w e l l . I n b o t h m e d i a , two i s o m e r i c p h e n y l m i g r a t i o n p r o d u c t s w e r e d e t e c t e d b y G C . T h e p h o t o p r o d u c t s w e r e i s o l a t e d i n a l a r g e s c a l e p h o t o l y s i s ( i n a c e t o n e ) a n d c h a r a c t e r i z e d a s t h e endo-trans- a n d exo-trans-5,6-diphenyl-3-methyl-b i c y c l o [ 3 . 1 . 0 ] h e x a n o n e s ( 7 5 a a n d 7 6 a ) b y s p e c t r o s c o p i c m e t h o d s ( S c h e m e 3 1 ) . T h e endo-trans i s o m e r 7 5 a i s t h e m a j o r p h o t o p r o d u c t b o t h i n s o l u t i o n a n d i n t h e s o l i d s t a t e . H o w e v e r , t h e p r o d u c t r a t i o ( 7 5 a : 7 6 a ) v a r i e s w i t h t h e s o l v e n t u s e d i n t h e s o l u t i o n p h o t o l y s i s , a n d t h e r a t i o a l s o c h a n g e s s l i g h t l y i n t h e s o l i d s t a t e d e p e n d i n g o n t h e t e m p e r a t u r e s a t w h i c h t h e c r y s t a l s o f 7 4 a w e r e i r r a d i a t e d ( s e e f o l l o w i n g d i s c u s s i o n o n p r o d u c t r a t i o s t u d i e s ) . T h e s t r u c t u r a l a s s i g n m e n t s o f t h e endo- a n d t h e exo- trans i s o m e r s a r e b a s e d o n a c o m p a r i s o n o f t h e i r ''"H NMR s p e c t r a ( F i g u r e 7 ) . F i r s t o f a l l , t h e trans g e o m e t r y o f t h e two p h e n y l g r o u p s i s a g a i n d e t e r m i n e d b y t h e c o u p l i n g c o n s t a n t o f 10 H z f o r t h e cis-c y c l o p r o p y l C H - C H c o u p l i n g . ' T h e exo-trans i s o m e r 7 6 a g i v e s a c h a r a c t e r i s t i c h i g h - f i e l d (6 = 1 . 1 5 ppm) m u l t i p l e t a s s i g n e d t o t h e h y d r o g e n a t o m o n t h e C - 3 c a r b o n a t o m . T h i s h i g h - f i e l d c h e m i c a l s h i f t i s a t t r i b u t e d t o t h e s h i e l d i n g e f f e c t f r o m t h e C - 6 p h e n y l g r o u p . I n - 64 -c o n t r a s t , t h e endo-trans i s o m e r - 7 5 a s h o w s a d o u b l e t s i g n a l f o r t h e m e t h y l g r o u p i n t h e h i g h - f i e l d r e g i o n (6 = 0 . 2 0 ppm) d u e t o t h e s a m e s h i e l d i n g e f f e c t o f t h e a r o m a t i c r i n g . S c h e m e 31 P h o t o c h e m i s t r y o f 4 , 4 - D i p h e n y l - 6 - a l k y l c y c l o h e x e n o n e s . T h e s t e r e o c h e m i s t r y o f t h e e x o - i s o m e r i s a l s o c o n f i r m e d b y a n i n d e p e n d e n t s y n t h e s i s ( S c h e m e 3 2 ) . M e t h y l a t i o n o f t h e k n o w n 4 ^ c o m p o u n d , t r a n s - 5 , 6 - d i p h e n y l - b i c y c l o [ 3 . 1 . 0 ] h e x a n o n e ( 3 9 a ) , g a v e o n l y t h e exo-trans i s o m e r 7 6 a . I t c a n b e s e e n t h a t a d d i t i o n o f t h e m e t h y l g r o u p s h o u l d o c c u r f r o m t h e l e s s h i n d e r e d s i d e w h i c h i s t h e b o t t o m s i d e o f t h e b i c y c l i c k e t o n e 3 9 a . I n a d d i t i o n , t h e e p i m e r i z a t i o n o f t h e endo i s o m e r 7 5 a t o t h e exo i s o m e r 7 6 a ( S c h e m e 3 2 ) , i n w h i c h t h e r a t i o o f 7 5 a : 7 6 a a t e q u i l i b r i u m w a s d e t e r m i n e d t o b e 1 7 : 8 3 b y G C , a l s o s u p p o r t s t h e a b o v e s t r u c t u r a l a s s i g n m e n t s . F i g u r e 7 P a r t i a l H NMR S p e c t r a o f exo-trans- a n d endo-trans-5,6-D i p h e n y l - 3 - m e t h y l b i c y c l o [ 3 . 1 . O ] h e x a n o n e s . - 66 -7 5 a 7 6 a S c h e m e 32 S y n t h e s e s o f P h o t o p r o d u c t s 7 6 a a n d 7 6 b a n d E p i m e r i z a t i o n o f P h o t o p r o d u c t 7 5 a . I n a s i m i l a r f a s h i o n , p h o t o l y s i s o f t h e e t h y l d e r i v a t i v e 74b i n a c e t o n e g a v e t h e exo- trans a n d t h e endo- trans b i c y c l i c k e t o n e s 7 5 b a n d 7 6 b i n a r a t i o o f 5 8 : 4 2 a s s h o w n i n S c h e m e 3 0 . T h e two p h o t o p r o d u c t s w e r e i s o l a t e d a n d c h a r a c t e r i z e d b y s p e c t r o s c o p i c m e t h o d s a n d a n i n d e p e n d e n t s y n t h e s i s o f p h o t o p r o d u c t 7 5 b ( S c h e m e 3 1 ) . S i n c e e n o n e 7 4 b p r o v e d t o b e a n o i l a t r o o m t e m p e r a t u r e , i r r a d i a t i o n o f t h i s c o m p o u n d i n t h e s o l i d s t a t e w a s n o t c a r r i e d o u t . H e r e t h e a u t h o r w o u l d l i k e t o m e n t i o n t h a t b y t h e t i m e t h i s p a r t o f t h e w o r k was c o m p l e t e d , a r e p o r t o n t h e s o l u t i o n p h a s e p h o t o c h e m i s t r y - 67 -o f c o m p o u n d 74a a p p e a r e d . T h e r e s u l t s o b t a i n e d i n t h e p r e s e n t s t u d y p r o v e d t o b e t h e same a s t h o s e r e p o r t e d . 2. Product Ratio Studies on Enone 74a i n Solution and i n the S o l i d State T u r n i n g t o t h e p r o d u c t r a t i o s t u d i e s , i t w a s i n t e r e s t i n g t o f i n d t h a t , f o r b o t h c o m p o u n d s 74a a n d 74b, t h e endo e p i m e r 75 w a s f o r m e d i n p r e f e r e n c e t o t h e exo s t e r e o i s o m e r 76 i n s o l u t i o n a s w e l l a s i n t h e s o l i d s t a t e . T a b l e 5 s u m m a r i z e s t h e endo:exo p r o d u c t r a t i o s f r o m t h e p h o t o l y s i s o f t h e 6 - m e t h y l c y c l o h e x e n o n e 74a i n s o l u t i o n . I t h a s b e e n s u g g e s t e d b y Z i m m e r m a n " ^ t h a t t h e p h o t o r e a r r a n g e m e n t o f 4 , 4 - d i p h e n y I - 6 -m e t h y l c y c l o h e x e n o n e l e a d i n g t o t h e f o r m a t i o n o f t h e m o r e s t e r i c a l l y h i n d e r e d endo p r o d u c t 75a ( m a j o r p h o t o p r o d u c t ) i s k i n e t i c a l l y c o n t r o l l e d . F u r t h e r s e n s i t i z a t i o n e x p e r i m e n t s c a r r i e d o u t b y Z i m m e r m a n a n d W e b e r " ' ' ' s h o w e d t h a t t h e r e a c t i o n o c c u r s f r o m t h e t r i p l e t e x c i t e d s t a t e o f t h e e n o n e m o i e t y 74a. B a s e d o n k i n e t i c s t u d i e s a n d m o l e c u l a r m e c h a n i c s c a l c u l a t i o n s , t h e s e a u t h o r s s u g g e s t e d t h a t t h e h a l f - m i g r a t e d s p e c i e s 111 l e a d i n g t o t h e C-3 endo b i c y c l i c p h o t o p r o d u c t 75a i s p r e f e r r e d e n e r g e t i c a l l y o v e r t h e h a l f - m i g r a t e d s p e c i e s 112 o r 113, w h i c h w o u l d a f f o r d t h e exo b i c y c l i c p h o t o p r o d u c t 76a ( F i g u r e 8). I t was a l s o c o n c l u d e d " 3 ^ t h a t t h e r a t e - a n d p r o d u c t - d e t e r m i n i n g s t e p o f t h e r e a r r a n g e m e n t m u s t come p r i o r t o o r n e a r t h e h a l f - m i g r a t i o n . - 68 -Table 5 Photoproduct Ratios of Endo:Exo (75a:76a) from Photorearrangement of 74a i n Various S o l v e n t s . a Solvent n-hexane benzene acetone a c e t o n i t r i l e ethanol methanol Endo:Exo Ratio 78:22 74:26b 70:30 66:34 57:43 55:45 a A n a l y s i s by gas chromatography. Reported value was 79:21 by i s o l a t i o n , see reference 57. F i g u r e 8 ORTEP Drawings of Molecular Mechanics Minimized Half-Migrated T r i p l e t B i r a d i c a l s (From reference 57 ). - 69 -A n i n t e r e s t i n g o b s e r v a t i o n made i n t h e p r e s e n t s t u d y i s t h a t t h e p r o d u c t r a t i o i n t h e p h o t o l y s i s o f 4 , 4 - d i p h e n y l - 6 - m e t h y l c y c l o h e x e n o n e (74a) i s s o l v e n t - d e p e n d e n t a s s e e n i n T a b l e 5 . I n g e n e r a l , n o n - p o l a r s o l v e n t s s u c h a s n - h e x a n e a n d b e n z e n e g i v e h i g h e r endo:exo r a t i o s , w h i l e t h e r a t i o s a r e l o w e r i n p o l a r s o l v e n t s ( a c e t o n e , a c e t o n i t r i l e , m e t h a n o l o r e t h a n o l ) . I t i s n o t y e t c l e a r why t h e s o l v e n t p o l a r i t y h a s s u c h a n e f f e c t o n t h e p r o d u c t s e l e c t i v i t y i n t h e p h o t o r e a r r a n g e m e n t o f e n o n e 74a. O n e p o s s i b i l i t y i s t h a t c h a n g i n g t h e s o l v e n t p o l a r i t y may a l t e r t h e n a t u r e o f t h e e x c i t e d s t a t e s p e c i e s o f t h e e n o n e m o i e t y , s u c h a s r e v e r s i n g t h e ( n - ? r * ) t o t h e (ir-n*) e n e r g y l e v e l s o r vice versa. T h e s e two d i f f e r e n t t r i p l e t e x c i t e d s t a t e s p e c i e s may h a v e t h e s a m e o r d i f f e r e n t p h o t o r e a c t i v i t y a n d p r o d u c t s e l e c t i v i t y . ^ A n o t h e r p o s s i b l e a l t e r n a t i v e , a s s u g g e s t e d i n some p h o t u r e a c t i o n s o f c y c l o h e x e n o n e c o m p o u n d s , i s t h a t t h e t w i s t e d e x c i t e d s p e c i e s ' o f t h e c y c l o h e x e n o n e m o i e t y m i g h t b e i n v o l v e d i n t h e p h o t o r e a r r a n g e m e n t . Some e v i d e n c e ^ h a s b e e n p r o v i d e d i n r e c e n t y e a r s t o s u p p o r t t h i s a l t e r n a t i v e m e c h a n i s m i n t h e p h o t o c h e m i s t r y o f c y c l o h e x e n o n e d e r i v a t i v e s . B u t i t i s n o t k n o w n h o w t h e s o l v e n t p o l a r i t y w o u l d a f f e c t r e a c t i o n s e l e c t i v i t y t h r o u g h t h e m e c h a n i s m o f t h e t w i s t e d e x c i t e d c y c l o h e x e n o n e s p e c i e s . F u r t h e r s t u d i e s n e e d t o b e c a r r i e d o u t i n o r d e r t o u n d e r s t a n d o n t h e s o l v e n t e f f e c t o n t h e p h o t o c h e m i s t r y o f e n o n e 74a. P r o d u c t R a t i o s i n t h e S o l i d S t a t e I r r a d i a t i o n o f c r y s t a l s o f 4 , 4 - d i p h e n y l - 6 - m e t h y l c y c l o h e x e n o n e (74a) a t A > 3 4 0 nm w a s c a r r i e d o u t a t r o o m a n d l o w t e m p e r a t u r e s , a s t h e - 70 -p h o t o l y s i s a t r o o m t e m p e r a t u r e w a s f o u n d t o r e s u l t i n p a r t i a l m e l t i n g o f t h e c r y s t a l s . T h e p r o d u c t d i s t r i b u t i o n s o f t h e endo a n d t h e exo s t e r e o i s o m e r s u n d e r v a r i o u s c o n d i t i o n s w e r e d e t e r m i n e d a n d a r e l i s t e d i n T a b l e 6 . T a b l e 6 P r o d u c t R a t i o s f r o m P h o t o l y s i s o f E n o n e 7 4 a i n t h e S o l i d S t a t e . a T e m p e r a t u r e ( ° C ) C o n v e r s i o n (%) C r y s t a l M e l t i n g Endo 75a:Exo 7 6 a 25 90 Y e s 66 : 34 25 65 Y e s 71 : 29 25 23 P a r t i a l 78 : 22 0 10 No 77 : 23 -25 6 No 80 : 20 -35 3 No 82 : 18 a A n a l y s i s b y g a s c h r o m a t o g r a p h y . T h e r e s u l t s i n T a b l e 6 s h o w t h a t t h e s o l i d s t a t e p h o t o l y s i s o f c o m p o u n d 7 4 a i s v e r y s i m i l a r t o i t s s o l u t i o n p h a s e c o u n t e r p a r t i n t e r m s o f t h e p h o t o p r o d u c t s a n d p r o d u c t d i s t r i b u t i o n . I t c a n b e a l s o s e e n f r o m T a b l e 6 t h a t t h e r e a c t i o n s e l e c t i v i t y i s h i g h e r a t l o w c o n v e r s i o n s a n d - 71 -a t l o w t e m p e r a t u r e s . O n t h e o t h e r h a n d , t h e s e l e c t i v i t y d e c r e a s e s u p o n c r y s t a l m e l t i n g , w h i c h i s l i k e l y d u e t o t h e p a r t i a l l o s s o f c r y s t a l l a t t i c e c o n t r o l o v e r t h e r e a c t i o n . T h e o v e r a l l m e c h a n i s m f o r t h e p h o t o r e a r r a n g e m e n t o f t h e C-6 s u b s t i t u t e d 4 , 4 - d i p h e n y l c y c l o h e x e n o n e s i n s o l u t i o n w a s s u g g e s t e d b y 57 Z i m m e r m a n e t al. t o . b e s i m i l a r t o t h a t f o r t h e 4 , 4 -d i a r y l c y c l o h e x e n o n e s a s s h o w n i n S c h e m e 3 3 . 116 S c h e m e 33 M e c h a n i s m o f P h o t o r e a r r a n g e m e n t o f 4 , 4 - D i p h e n y l -c y c l o h e x e n o n e s . - 72 -Although the proposed mechanism seems s a t i s f a c t o r y i n general, one thing i s unclear. That i s , the two phenyl groups are non-equivalent i n terms of t h e i r stereochemistry r e l a t i v e to the C-6 methyl groups (R — methyl); one i s c i s to the 6-methyl and the other i s t r a n s . This di f f e r e n c e can also be considered i n another way. From molecular models and conformational analysis, i t i s apparent that 4,4-diphenyl-6-methylcyclohexenone (74a) may e x i s t i n two low-energy conformations i n s o l u t i o n (Scheme 34). The two conformers are presumably i n rapid equilibrium, but the conformation A w i l l be predominant owing to less s t e r i c hindrance. I t can be noted that, i n e i t h e r of the conformations, the two phenyl groups are non-equivalent. One phenyl group i s pseudo-a x i a l , the other i s pseudo-equatorial. Bearing t h i s i n mind, i t seems l i k e l y that ~the two phenyl groups could have d i f f e r e n t migratory aptitudes i n the s o l i d state. Ph. ' = 0 < • P h Me H A B Scheme 34 Conformational Equilibrium of 6-Methyl Cyclohexenone 74a. - 73 -I n p r i n c i p l e , b o t h t h e p s e u d o - a x i a l a n d t h e p s e u d o - e q u a t o r i a l p h e n y l g r o u p s a r e c a p a b l e o f m i g r a t i n g u p o n i r r a d i a t i o n . I n t h e p r o p o s e d m e c h a n i s m f o r p h o t o r e a r r a n g e m e n t o f 4 , 4 - d i a r y l c y c l o h e x e n o n e s , 38 Z i m m e r m a n s u g g e s t e d t h a t t h e r e a c t i o n p r o c e e d s b y p s e u d o - a x i a l p h e n y l g r o u p m i g r a t i o n l e a d i n g t o t h e h a l f - m i g r a t e d s p e c i e s 116 ( S c h e m e 33). I n a d d i t i o n , i t w a s s u g g e s t e d t h a t a r y l g r o u p m i g r a t i o n f r o m C - 4 t o C -3 a n d c y c l o p r o p a n e r i n g c l o s u r e b y b o n d f o r m a t i o n b e t w e e n C - 2 a n d C - 4 may p r o c e e d i n a c o n c e r t e d f a s h i o n ( S c h e m e 33) t o g i v e t h e p r e d o m i n a n t trans d i a r y l b i c y c l i c k e t o n e . B a s e d o n t h e a b o v e , we p r o p o s e t h a t , i n t h e c a s e o f 4 , 4 - d i p h e n y l -6 - m e t h y l c y c l o h e x e n o n e ( 7 4 a ) , t h e two p h o t o p r o d u c t s 7 5 a a n d 7 6 a a r e d e r i v e d f r o m m i g r a t i o n o f d i f f e r e n t p h e n y l g r o u p s . A s s h o w n i n S c h e m e 35, t h e m i g r a t i o n o f t h e p h e n y l g r o u p w h i c h i s cis t o t h e C - 6 m e t h y l g r o u p g i v e s t h e endo-trans s t e r e o i s o m e r 7 5 a , w h e r e a s t h e exo-trans i s o m e r 7 6 a i s f o r m e d via t h e m i g r a t i o n o f t h e o t h e r p h e n y l g r o u p t h a t i s trans t o t h e C - 6 m e t h y l . T h i s a s s u m p t i o n s e e m s r e a s o n a b l e i f o n e c o n s i d e r s t h a t p h e n y l m i g r a t i o n a n d c y c l o p r o p y l r i n g c l o s u r e a r e s i m u l t a n e o u s a s m e n t i o n e d a b o v e . A s a m a t t e r o f f a c t , t h e c o n c e r t e d n a t u r e o f p h e n y l m i g r a t i o n a n d r i n g c l o s u r e i s s u p p o r t e d b y t h e e v i d e n c e t h a t t h e two p h e n y l g r o u p s f o r b o t h p h o t o p r o d u c t s 7 5 a a n d 7 6 a a r e trans t o o n e a n o t h e r . - 74 S c h e m e 35 Two P a t h w a y s o f P h o t o r e a r r a n g e m e n t o f C y c l o h e x e n o n e 7 4 a . I n t h e m e c h a n i s m p r o p o s e d a b o v e , we n o t e t h a t m i g r a t i o n o f t h e p s e u d o - e q u a t o r i a l p h e n y l g r o u p i n c o n f o r m a t i o n A ( S c h e m e 3 4 ) w i l l p r o d u c e t h e endo-trans i s o m e r 7 5 a , a n d m i g r a t i o n o f t h e p s e u d o - a x i a l p h e n y l w i l l g i v e t h e exo-trans i s o m e r 7 6 a . O n t h e o t h e r h a n d , t h e s i t u a t i o n i s r e v e r s e d i n t h e c a s e o f c o n f o r m a t i o n B ( S c h e m e 3 4 ) . A s m e n t i o n e d a b o v e , t h e p s e u d o - e q u a t o r i a l a n d t h e p s e u d o - a x i a l p h e n y l g r o u p s i n e i t h e r o f t h e c o n f o r m a t i o n s may s h o w d i f f e r e n t m i g r a t o r y a p t i t u d e s u p o n i r r a d i a t i o n . H o w e v e r , s u c h d i f f e r e n c e s i n m i g r a t i o n - 75 -tendency may not be e a s i l y distinguished i n s o l u t i o n owing to the f a s t equilibrium. In contrast, the s o l i d state r e s u l t s may help to answer t h i s question because such conformational changes i n c r y s t a l s are r e s t r i c t e d . Without knowing the molecular and c r y s t a l structure at the present time, we may assume that the conformation which enone 74a adopts i n the c r y s t a l l i n e state would preferably be the conformation A. This i s based on the general observation that organic molecules are u s u a l l y found to c r y s t a l l i z e i n or near t h e i r minimum energy conformations.^" I f t h i s assumption stands, the pseudo-equatorial phenyl group would migrate p r e f e r e n t i a l l y i n the c r y s t a l s of 74a, as the major s o l i d state photoproduct i s the endo-trans stereoisomer 75a. Such a conclusion must be regarded as tentative u n t i l further information on the c r y s t a l structure of 74a becomes av a i l a b l e . A f i n a l cautionary point i s that the s o l i d state r e s u l t s might not be relevant to the same r e a c t i o n i n s o l u t i o n , even though the products and the product r a t i o s i n the two media are s i m i l a r . In solution, a l t e r n a t i v e mechanisms leading to the photoproducts 75a and 76a i n the case of 4,4-diphenyl-6-methylcyclohexenone might be possible, such as v i a the twisted species. ' e Such a mechanism i s probably u n l i k e l y i n the s o l i d state because any d r a s t i c conformational or c o n f i g u r a t i o n a l changes w i l l be r estrained by the c r y s t a l l a t t i c e . I I I . Studies on the Di-7r-Methane Photorearrangement of 9-Substituted Dibenzobarrelene Diesters - 76 -The photochemistry of dibenzobarrelene and several of i t s substituted derivatives i n solu t i o n was f i r s t investigated by Ciganek i n 1966."^ One t y p i c a l example was that d i r e c t or s e n s i t i z e d i r r a d i a t i o n of dimethyl dibenzobarrelene dicarboxylate 60 gave the corresponding dibenzosemibullvalene d e r i v a t i v e 63 e x c l u s i v e l y i n s o l u t i o n (Scheme 36). Zimmerman and co-workers also studied the r e l a t e d photochemical transformations of barrelenes and benzobarrelenes i n the mid-1960s. Based on t h e i r studies of a series of barrelene analogues, Zimmerman proposed the s o - c a l l e d di-7r-methane rearrangement mechanism as discussed previously (Scheme 10 on page 27). Subsequent studies showed that the di-7r-methane rearrangement of dibenzobarrelene compounds was a t r i p l e t -s p e c i f i c reaction, and that s i n g l e t state r e a c t i o n by'direct i r r a d i a t i o n afforded dibenzocyclooctatetraene products. COOR ROOC ROOC COOR hv c r y s t a l or solution 26 R = CH(CH3)2 60 R = Me 27 R = CH(CH3)2 63 R = Me Scheme 36 Phototransformation of Dibenzobarrelene Diesters to Dibenzosemibullvalenes. - 77 I n r e c e n t y e a r s , S c h e f f e r , T r o t t e r a n d c o - w o r k e r s ' h a v e s t u d i e d t h e p h o t o c h e m i c a l b e h a v i o r o f d i b e n z o b a r r e l e n e c o m p o u n d s i n t h e s o l i d s t a t e . I t h a s b e e n d e m o n s t r a t e d t h a t t h e s e c o m p o u n d s , s u c h a s d i e s t e r s 26 a n d 60, c a n a l s o u n d e r g o s m o o t h p h o t o r e a r r a n g e m e n t i n t h e c r y s t a l l i n e s t a t e g i v i n g t h e same p r o d u c t s a s f o u n d i n s o l u t i o n . G a r c i a - G a r i b a y et a 2 6 1 a s j j f l w e ( j t h a t t h e c r y s t a l l a t t i c e h a s s i g n i f i c a n t e f f e c t s o n t h e r e a c t i v i t y a n d s e l e c t i v i t y o f s u c h d i - 7 r - m e t h a n e p h o t o t r a n s f o r m a t i o n s o f d i b e n z o b a r r e l e n e d i e s t e r d e r i v a t i v e s . T h e s o l u t i o n p h a s e p h o t o c h e m i s t r y o f , , a n u m b e r o f 9 - s u b s t i t u t e d 9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o a n t h r a c e n e - 1 1 , 1 2 - d i c a r b o x y l a t e d e r i v a t i v e s h a s 51 52 b e e n s t u d i e d b y R i c h a r d a n d I w a m u r a . I n i t i a l i n v e s t i g a t i o n s o n t h e s o l i d s t a t e p h o t o r e a c t i o n s o f 9 - s u b s t i t u t e d e t h e n o a n t h r a c e n e s c a r r i e d o u t b y o u r g r o u p s h o w e d t h a t t h e r e a c t i v i t y a n d r e g i o s e l e c t i v i t y o f t h i s p h o t o t r a n s f o r m a t i o n c o u l d b e a f f e c t e d b y t h e c r y s t a l l a t t i c e . I n o r d e r t o t e s t t h e g e n e r a l i t y o f t h e c r y s t a l l a t t i c e e f f e c t o n t h e r e g i o s e l e c t i v i t y o f p h o t o c h e m i c a l t r a n s f o r m a t i o n s o f 9 - s u b s t i t u t e d d i b e n z o b a r r e l e n e s , s e v e r a l s u b s t r a t e s w e r e s y n t h e s i z e d a n d p h o t o l y z e d i n t h e s o l i d a n d s o l u t i o n p h a s e s . A . P h o t o c h e m i s t r y o f 9 - F o r m y l , 9 - H y d r o x y m e t h y l a n d 9 - A c e t o x y m e t h y l 9 , 1 0 -E t h e n o a n t h r a c e n e - l l , 1 2 - d i c a r b o x y l a t e s ( 9 4 , 95 a n d 9 3 c ) D i r e c t a n d a c e t o n e - s e n s i t i z e d i r r a d i a t i o n s o f t h e t i t l e c o m p o u n d s w e r e f i r s t c a r r i e d o u t i n s o l u t i o n ( S c h e m e 37 ) . E a c h p h o t o p r o d u c t f r o m t h e c o r r e s p o n d i n g p r e p a r a t i v e p h o t o l y s i s w a s i s o l a t e d a n d p u r i f i e d b y - 78 -c o l u m n c h r o m a t o g r a p h y , a n d t h e s t r u c t u r e s o f t h e p h o t o p r o d u c t s w e r e e s t a b l i s h e d b y a n a l y t i c a l a n d s p e c t r o s c o p i c m e t h o d s . C r y s t a l s o f t h e s e c o m p o u n d s w e r e i r r a d i a t e d a t r o o m t e m p e r a t u r e a n d t h e p r o d u c t s w e r e a n a l y z e d b y c o m p a r i s o n o f t h e i r G C r e t e n t i o n t i m e s a n d G C - M S d a t a w i t h t h e r e s u l t s f r o m s o l u t i o n . I t w a s f o u n d t h a t i r r a d i a t i o n o f t h e 9 - f o r m y l d e r i v a t i v e 9 4 i n b o t h m e d i a l e d t o t h e f o r m a t i o n o f a s i n g l e p r o d u c t , 4 b - f o r m y l ^ d i b e n z o s e m i b u l l v a l e n e d i e s t e r 118. I n c o n t r a s t , I w a m u r a et al^ r e p o r t e d t h a t t h e p h o t o t r a n s f o r m a t i o n o f 94 i n a c e t o n e g a v e b o t h 4 b - a n d 8 b -f o r m y l f i s o m e r s 118 a n d 122 i n a r a t i o o f 8 8 : 1 2 . I n t h e p r e s e n t s t u d y , t h e r e f o r e , t h i s r e a c t i o n was e x a m i n e d c a r e f u l l y i n d i f f e r e n t s o l v e n t s i n c l u d i n g a c e t o n e a n d d e u t e r o c h l o r o f o r m , a n d t h e p h o t o l y s a t e was a n a l y z e d b y GC a n d "^H NMR. I t w a s s h o w n t h a t , i n e a c h c a s e , t h e 4 b -f o r m y l i s o m e r 118 i s t h e o n l y p h o t o p r o d u c t . The systematic numbering for dibenzosemibullvalene structure is presented below: - 79 T h e s o l u t i o n p h a s e p h o t o l y s i s o f c o m p o u n d s 95 a n d 9 3 c r e s u l t e d i n t w o r e g i o i s o m e r i c d i b e n z o s e m i b u l l v a l e n e p r o d u c t s i n e a c h i n s t a n c e . I n t h e c a s e o f c o m p o u n d 9 5 , t h e f o r m a t i o n o f p r o d u c t 123 was d e t e r m i n e d b y a d i r e c t ''"H NMR a n a l y s i s o f t h e r e a c t i o n m i x t u r e i n CDCI3, a s t h i s c o m p o u n d d e c o m p o s e d t o t h e c o r r e s p o n d i n g l a c t o n e b y a n e l i m i n a t i o n o f m e t h a n o l d u r i n g t h e p u r i f i c a t i o n p r o c e d u r e . T h i s w i l l b e d i s c u s s e d i n a s u b s e q u e n t p a r t o f t h e t h e s i s . F o r b o t h s y s t e m s , i t w a s d e t e r m i n e d t h a t t h e 4 b - s u b s t i t u t e d i s o m e r s 119 a n d 120 w e r e t h e m a j o r p h o t o p r o d u c t s i n s o l u t i o n . S o l i d s t a t e p h o t o l y s i s o f 95 a n d 9 3 c g a v e b o t h r e g i o i s o m e r i c d i b e n z o s e m i b u l l v a l e n e s w i t h t h e 4 b - s u b s t i t u t e d i s o m e r a s t h e p r e d o m i n a n t 1 1 7 1 1 hu zzJ p a t h A 4 b - i s o m e r 1 1 8 R - CHO 1 1 9 R - CH2OH 1 2 0 R - C H 2 O C O C H 3 hu p a t h B E - C O 2 C H 3 9 4 R - CHO 95 R - CH20H 9 3 c R = CH2OCOCH3 121 \ I 8 b - i s o m e r 122 R - CHO 123 R - CH2OH 1 2 4 R - C H 2 O C O C H 3 S c h e m e 37 P h o t o t r a n s f o r m a t i o n o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e s . - 80 -p h o t o p r o d u c t i n e a c h c a s e ; s m a l l a m o u n t s o f o t h e r p h o t o p r o d u c t s w e r e d e t e c t e d b y G C . T h e s e m i n o r p r o d u c t s w e r e n o t c h a r a c t e r i z e d o w i n g t o t h e i n e f f i c i e n c y o f t h e s o l i d s t a t e r e a c t i o n . T h e s t r u c t u r e o f e a c h p h o t o p r o d u c t was d e r i v e d b y a p p l i c a t i o n o f t h e w e l l e s t a b l i s h e d d i - j r - m e t h a n e m e c h a n i s m a n d s u p p o r t e d b y s p e c t r o s c o p i c s t u d i e s . T h e r e g i o c h e m i s t r y o f t h e p h o t o p r o d u c t s w a s b a s e d p r i m a r i l y o n t h e d i f f e r e n c e o f c h e m i c a l s h i f t s f o r t h e c y c l o p r o p y l a n d t h e b e n z y l i c m e t h i n e p r o t o n s o f d i b e n z o s e m i b u l l v a l e n e d i e s t e r s i n t h e 1 H NMR s p e c t r a . ' ' I n f o r m a t i v e l y , t h e m e t h i n e p r o t o n a t t h e 4 b -p o s i t i o n a p p e a r s a t 5 = 5.0-5.1 p p m ; i n c o n t r a s t , t h e 8 b - p r o t o n o n t h e c y c l o p r o p a n e r i n g g i v e s r i s e t o a s i g n a l a t 6 = 4.2-4.5 p p m . T h e s e e m p i r i c a l v a l u e s a r e c o n s i d e r e d t o b e g e n e r a l f o r c o m p o u n d s o f t h i s t y p e a n d a r e u s e d t o c h a r a c t e r i z e a n d d i s t i n g u i s h e a c h d i b e n z o s e m i b u l l v a l e n e p r o d u c t d e s c r i b e d i n t h e p r e s e n t t h e s i s . F u r t h e r m o r e , m o l e c u l a r c r y s t a l s t r u c t u r e s o f a f e w r e l a t e d d i b e n z o s e m i b u l l v a l e n e c o m p o u n d s h a v e b e e n d e t e r m i n e d i n o u r l a b o r a t o r y , a n d t h e s t r u c t u r e s o b t a i n e d b y X - r a y c r y s t a l l o g r a p h i c s t u d i e s a r e a l l i n a g r e e m e n t w i t h t h e a s s i g n m e n t b y t h e s p e c t r o s c o p i c m e t h o d s . I n t h e c a s e o f p h o t o p r o d u c t 1 1 9 , t h e s t r u c t u r e w a s a l s o s u p p o r t e d b y a n i n d e p e n d e n t s y n t h e s i s ( S c h e m e 3 8 ) . A s e l e c t i v e r e d u c t i o n o f t h e c o r r e s p o n d i n g a l d e h y d e 1 1 8 , w h i c h was p r e p a r e d f r o m t h e p h o t o l y s i s o f 52 c o m p o u n d 94 , b y s o d i u m b o r o h y d r i d e l e a d s t o 4 b - h y d r o x y m e t h y l d i b e n z o s e m i b u l l v a l e n e d i e s t e r 1 1 9 . - 81 -Scheme 38 Synthesis of Photoproduct 119 by a Se l e c t i v e Reduction. B. S o l i d State Results 1. R e g i o s e l e c t i v i t y i n the S o l i d State vs Solution The product d i s t r i b u t i o n i n sol u t i o n and i n the s o l i d state, which represents the bridging r e g i o s e l e c t i v i t y f o r compounds 93c, 94 and 95, i s summarized i n Table 7. F i r s t l y , i t can be seen from the Table that the formation of the 4b-substituted dibenzosemibullvalene products i s greatly favored f o r a l l three substrates, both i n s o l u t i o n and i n the s o l i d state. Secondly, the data show that the differ e n c e i n r e g i o s e l e c t i v i t y between s o l u t i o n and the s o l i d state f o r the d i - 7 r -methane photoreaction of these compounds i s small. - 82 T a b l e 7 P r o d u c t R a t i o s i n P h o t o r e a r r a n g e m e n t o f 9-S u b s t i t u t e d 9 , 1 0 - E t h e n o a n t h r a c e n e s . a 9 - S u b s t i t u e n t M e d i u m 4 b - i s o m e r 1 1 8 - 1 2 0 8 b - i s o m e r 1 2 2 - 1 2 4 CHO ( 9 4 ) A c e t o n e 1 0 0 0 C r y s t a l 1 0 0 0 C H 2 0 H ( 9 5 ) C h l o r o f o r m b 75 25 C r y s t a l 60 4 0 C H 2 0 A c ( 9 3 c ) A c e t o n e 89 11 C r y s t a l 70 30 a b J. A n a l y s i s b y g a s c h r o m a t o g r a p h y . P h o t o l y s i s i n CDCI3; a n a l y s i s b y H NMR. T h e r e s u l t s o b t a i n e d i n t h e p r e s e n t s t u d y o n t h e s o l u t i o n p h a s e p h o t o c h e m i s t r y o f c o m p o u n d s 9 3 c , 94 a n d 95 a r e i n a g r e e m e n t w i t h t h e g e n e r a l o b s e r v a t i o n s t h a t w e r e m a d e i n t h e p h o t o c h e m i s t r y o f t h e 9-s u b s t i t u t e d 9 , 1 0 - e t h e n o a n t h r a c e n e s s t u d i e d b y R i c h a r d " ^ a n d b y 52 51 I w a m u r a . I t was s u g g e s t e d t h a t t h e k e y f a c t o r i n u n d e r s t a n d i n g t h e s u b s t i t u e n t e f f e c t s o n t h e r e a c t i o n r e g i o s e l e c t i v i t y l i e s i n t h e i n i t i a l s t a g e s o f t h e r e a r r a n g e m e n t , i n p a r t i c u l a r t h e r e l a t i v e s t a b i l i t y o f t h e f i r s t i n t e r m e d i a t e s 117 a n d 1 2 1 ( S c h e m e 37 ) , s i n c e t h e i n i t i a l s t e p o f t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t h a s b e e n s u g g e s t e d b y Z i m m e r m a n 4 3 t o b e 52 t h e r a t e - d e t e r m i n i n g s t e p . I w a m u r a a r g u e d t h a t t h e 9 - s u b s t i t u e n t a f f e c t s t h e s t a b i l i t y o f t h e i n i t i a l l y f o r m e d i n t e r m e d i a t e s i n t h e s a m e 83 w a y a s t h a t o b s e r v e d i n t h e s u b s t i t u e n t e f f e c t s o n t h e e q u i l i b r i u m b e t w e e n n o r c a r a d i e n e s a n d t h e c o r r e s p o n d i n g c y c l o h e p t a t r i e n e ( S c h e m e 73 73 3 9 ) . I t i s k n o w n e x p e r i m e n t a l l y a s w e l l a s t h e o r e t i c a l l y t h a t e l e c t r o n - w i t h d r a w i n g g r o u p s , s u c h a s C N , CO2CH3 a n d C H O , s t a b i l i z e t h e c y c l o p r o p a n e r i n g a n d t h u s f a v o r t h e n o r c a r a d i e n e t a u t o m e r 126 o v e r t h e c y c l o h e p t a t r i e n e 125 ( S c h e m e 3 9 ) ; i n c o n t r a s t , e l e c t r o n - d o n a t i n g g r o u p s , e.g. OCH3, may d e s t a b i l i z e t h e c y c l o p r o p a n e r i n g a n d t h e r e f o r e s h i f t t h e e q u i l i b r i u m t o w a r d t h e l e f t . I t s h o u l d b e m e n t i o n e d t h a t some c o n v e r s e e x p e r i m e n t a l d a t a e x i s t ^ 4 e i n r e g a r d t o t h e d e s t a b i l i z a t i o n o f c y c l o p r o p y l r i n g b y e l e c t r o n - d o n a t i n g g r o u p s . S u c h g e n e r a l i z a t i o n s a r e u s e f u l i n i n t e r p r e t i n g t h e r e g i o s e l e c t i v i t y i n t h e p h o t o l y s i s o f 9 -s u b s t i t u t e d d i b e n z o b a r r e l e n e s . T h u s , i f t h e s u b s t i t u e n t R i s a n a l k y l o r some o t h e r e l e c t r o n - d o n a t i n g g r o u p , t h e i n t e r m e d i a t e 1 2 1 w o u l d b e l e s s s t a b l e t h a n 1 1 7 . T h e r e f o r e p a t h A , w i t h t h e i n i t i a l b e n z o - v i n y l b r i d g i n g f r o m t h e s i d e w i t h o u t t h e 9 - s u b s t i t u e n t , i s t h e p r e f e r r e d p a t h w a y ( S c h e m e 37 ) l e a d i n g t o t h e 4b - s u b s t i t u t e d d i b e n z o s e m i b u l l v a l e n e d e r i v a t i v e s 1 1 8 - 1 2 0 . A l t h o u g h p a t h w a y B l e a d i n g t o 1 2 1 w o u l d b e e x p e c t e d t o b e f a v o r e d b y t h e e l e c t r o n - w i t h d r a w i n g g r o u p ( C H O ) i n t h e c a s e o f 9 -f o r m y l d e r i v a t i v e 9 4 , t h e o b s e r v e d p r o d u c t 118 i s f o r m e d e x c l u s i v e l y 52 t h r o u g h p a t h w a y A . T h i s s i t u a t i o n was s u g g e s t e d b y I w a m u r a b e i n g d u e t o t h a t f o r m a t i o n o f t h e i n t e r m e d i a t e 1 2 1 i s k i n e t i c a l l y i n h i b i t e d b y t h e e l e c t r o n d e f i c i e n t g r o u p , a l t h o u g h 1 2 1 m i g h t b e t h e r m o d y a m i c a l l y m o r e s t a b l e t h a n c y c l o p r o p y l d i c a r b i n y l b i r a d i c a l 1 1 7 . - 84 -R R 1 2 5 126 R = e l e c t r o n - d o n a t i n g o r w i t h d r a w i n g g r o u p S c h e m e 39 E l e c t r o n i c E f f e c t o n V a l e n c e T a u t o m e r i z a t i o n o f C y c l o h e p t a t r i e n e a n d N o r c a r a d i e n e . T u r n i n g now t o t h e b r i d g i n g r e g i o s e l e c t i v i t y o f t h e 9 - s u b s t i t u t e d 9 , 1 0 - e t h e n o a n t h r a c e n e d e r i v a t i v e s 9 3 c , 94 a n d 95 i n t h e s o l i d s t a t e , we n o t e t h a t t h e c r y s t a l l a t t i c e h a s o n l y a s l i g h t e f f e c t o n t h e r e a c t i o n p a t h w a y ; t h e o b s e r v e d r e g i o s e l e c t i v i t y i n t h e c r y s t a l l i n e p h a s e i s q u i t e s i m i l a r t o t h a t i n s o l u t i o n , i n w h i c h p a t h A p r e v a i l s . S u c h o b s e r v a t i o n s h a v e a l s o b e e n made ( s e e f o l l o w i n g s e c t i o n s ) i n t h e s t u d i e s o f o t h e r 9-s u b s t i t u t e d d i b e n z o b a r r e l e n e s a n d i t w o u l d s e e m t o b e a g e n e r a l t r e n d f o r t h i s c l a s s o f c o m p o u n d s . 2 . M o l e c u l a r C r y s t a l S t r u c t u r e o f 9 - F o r m y l - 9 , 1 0 - E t h e n o a n t h r a c e n e D i e s t e r I n o r d e r t o s t u d y s t r u c t u r e - r e a c t i v i t y r e l a t i o n s h i p s i n t h e s o l i d s t a t e p h o t o c h e m i s t r y o f 9 - s u b s t i t u t e d d i b e n z o b a r r e l e n e d i e s t e r s , c r y s t a l 94 - 85 -and molecular structures of a number of these substrates have been determined i n the present work.t In general, s p e c i f i c molecular conformations and intermolecular arrangements of the reactants i n the c r y s t a l s are considered to be the key factors i n understanding the s o l i d state photochemical behavior. The molecular c r y s t a l structure of 9-formyl dibenzobarrelene d i e s t e r 94 i s given i n Figure 9. The c r y s t a l packing diagram i s found i n Figure 10. F i g u r e 9 Stereodiagram of the Molecule Dimethyl 9-Formyl-9,10-dihydro-9,10-ethenoanthracene-ll,12-dicarboxylate (94). t Al l crystal structures presented in this thesis were determined by Dr. P. R. Pokkuluri at Chemistry Department of UBC unless otherwise mentioned. - 86 -F i g u r e 10 C r y s t a l P a c k i n g D i a g r a m o f D i m e t h y l 9 - F o r m y l - 9 , 1 0 - d i h y d r o -9 , 1 0 - e t h e n o a n t h r a c e n e - 1 1 , 1 2 - d i c a r b o x y l a t e ( 9 4 ) . T h e c r y s t a l s t r u c t u r e a n a l y s i s r e v e a l e d t h e i n t e r e s t i n g f e a t u r e t h a t t h e two e s t e r g r o u p s o f c o m p o u n d 94 a r e o r i e n t a t e d d i f f e r e n t l y i n r e l a t i o n t o t h e v i n y l d o u b l e b o n d i n t h e s o l i d s t a t e . T h e s p e c i f i c m o l e c u l a r c o n f o r m a t i o n s h o w s t h a t t h e c a r b o n y l g r o u p o f o n e o f t h e e s t e r s , w h i c h i s o n t h e C - ( 1 2 ) v i n y l c a r b o n a t o m o f t h e m o l e c u l e , i s c o m p l e t e l y o u t o f c o n j u g a t i o n w i t h t h e d o u b l e b o n d ; i n c o n t r a s t , t h e c a r b o n y l g r o u p f r o m t h e o t h e r e s t e r i s o r i e n t a t e d i n c o m p l e t e c o n j u g a t i o n . I f t h e e l e c t r o n i c s t a b i l i z i n g e f f e c t o f t h e e s t e r s u b s t i t u e n t s o n t h e i n i t i a l b i r a d i c a l s 117 a n d 1 2 1 d e t e r m i n e s t h e r e a c t i o n r e g i o s e l e c t i v i t y , i . e . p a t h s A a n d B ( S c h e m e 37), o n e m i g h t e x p e c t t h a t p a t h B w o u l d b e p r e f e r r e d i n t h e s o l i d s t a t e . T h i s i s b e c a u s e t h a t t h e b i r a d i c a l i n t e r m e d i a t e 1 2 1 f r o m t h e i n i t i a l b e n z o - v i n y l - 87 b o n d i n g v i a p a t h w a y B w o u l d b e m o r e s t a b i l i z e d b y t h e c o n j u g a t e d c a r b o n y l g r o u p t h a n t h e b i r a d i c a l i n t e r m e d i a t e 117 v i a p a t h w a y A , a s s u m i n g t h a t e s t e r g r o u p s d o n o t m o v e o r r o t a t e i n t h e s o l i d s t a t e . B u t , t h e e x p e r i m e n t a l r e s u l t d o e s n o t a g r e e w i t h s u c h s p e c u l a t i o n . I n t h e s o l i d s t a t e p h o t o l y s i s , p r o d u c t 122 f r o m p a t h B w a s n o t o b s e r v e d . I n a c o m p a r i s o n t o t h e p r e v i o u s s t u d i e s i n o u r g r o u p , ^ 4 , 7 5 ^ t s e e m s t o s u g g e s t t h a t t h e s t e r i c e f f e c t f r o m t h e c r y s t a l l a t t i c e may p l a y a m o r e i m p o r t a n t r o l e i n d e t e r m i n i n g t h e r e g i o s e l e c t i v i t y o f t h e d i - 7 r - m e t h a n e p h o t o r e a r r a n g e m e n t i n t h e c a s e o f c o m p o u n d 9 4 i n s t e a d o f t h e e l e c t r o n i c s t a b i l i z i n g e f f e c t . I n o n e i n s t a n c e o f t h e p r e v i o u s w o r k , S c h e f f e r , T r o t t e r a n d c o - w o r k e r s ^ 4 i n v e s t i g a t e d t h e s o l u t i o n a n d s o l i d s t a t e p h o t o t r a n s f o r m a t i o n s o f c o m p o u n d s 1 2 7 a - d ( S c h e m e 4 0 ) , i n w h i c h t h e m e t h y l e s t e r s u b s t i t u e n t r e m a i n e d u n c h a n g e d w h i l e t h e s e c o n d e s t e r g r o u p w a s v a r i e d f r o m e t h y l t o t e r t - b u t y l . I n s o l u t i o n , t h e r e was a s m a l l p r e f e r e n c e i n a l l f o u r c a s e s f o r f o r m a t i o n o f w h a t w a s s u g g e s t e d t o b e t h e l e s s h i n d e r e d p h o t o p r o d u c t 1 2 9 , b u t i n t h e s o l i d s t a t e , t h e r e g i o s e l e c t i v i t y w a s i r r e g u l a r . T h e 1 2 9 : 1 3 1 r a t i o i n t h e s o l i d v a r i e d w i t h t h e R g r o u p i n t h e f o l l o w i n g w a y : 4 5 : 5 5 ( R . = e t h y l ) , 9 3 : 7 (R = i s o p r o p y l ) , 9 9 : 1 (R = ( ± ) - s e c - b u t y l ) a n d 1 5 : 8 5 (R «= t - b u t y l ) . Two p o s s i b l e e x p l a n a t i o n s w e r e c o n s i d e r e d f o r t h e s o l i d s t a t e r e s u l t s . T h e f i r s t o n e w a s t h a t t h e p r e f e r e n c e f o r f o r m a t i o n o f e i t h e r b i r a d i c a l 128 o r 130 d e p e n d s o n w h i c h e s t e r g r o u p i s b e t t e r o r i e n t e d b y t h e c r y s t a l l a t t i c e f o r r a d i c a l s t a b i l i z a t i o n t h r o u g h r e s o n a n c e . H o w e v e r , t h i s was f o u n d s u b s e q u e n t l y t o b e i n c o m p a t i b l e w i t h t h e c r y s t a l s t r u c t u r e c o r r e l a t i o n s . T h e s e c o n d e x p l a n a t i o n i n v o l v e d t h e p o s s i b i l i t y o f s t e r i c e f f e c t s b e t w e e n t h e r e a c t i n g m o l e c u l e a n d i t s l a t t i c e n e i g h b o r s , w h i c h w a s s u g g e s t e d t o b e t h e c o n t r o l l i n g f a c t o r . S c h e f f e r ^ r e a s o n e d t h a t i t - 88 -i s t h e e s t e r s u b s t i t u e n t a t t a c h e d t o t h e b r i d g i n g v i n y l c a r b o n a t o m t h a t m o v e s m o s t d u r i n g t h e i n i t i a l s t a g e s o f r e a c t i o n , a n d t h a t o n l y t h e b r i d g i n g w h i c h i n v o l v e s l e s s i n t e r m o l e c u l a r i n t e r a c t i o n s i n t h e e s t e r m o v e m e n t m i g h t b e f a v o r e d i n t h e s o l i d s t a t e . F u r t h e r c a l c u l a t i o n s f r o m a c o m p u t e r s i m u l a t i o n o f t h e e s t e r m o t i o n s i n t e r m s o f t h e i n t e r m o l e c u l a r n o n - b o n d e d r e p u l s i o n e n e r g i e s w e r e i n a c c o r d w i t h t h e s o l i d s t a t e r e s u l t s . S c h e m e 40 P h o t o t r a n s f o r m a t i o n o f U n s y m m e t r i c a l D i b e n z o b a r r e l e n e D i e s t e r s . - 89 I V . A s y m m e t r i c I n d u c t i o n via P h o t o r e a c t i o n s o f C h i r a i C r y s t a l s A s w a s b r i e f l y d i s c u s s e d i n t h e i n t r o d u c t i o n s e c t i o n , o r g a n i c m o l e c u l e s , e i t h e r c h i r a i o r a c h i r a l , c a n c r y s t a l l i z e i n c h i r a i s p a c e g r o u p s . U p o n a c h e m i c a l r e a c t i o n o f t h e c h i r a i c r y s t a l s , o p t i c a l l y a c t i v e p r o d u c t s c a n b e g e n e r a t e d p r o v i d e d t h a t t h e p r o d u c t s a r e c h i r a i . S u c h p r o c e s s i n v o l v e s a t r a n s f o r m a t i o n o f t h e c r y s t a l c h i r a l i t y i n t o t h e m o l e c u l a r c h i r a l i t y o f t h e p r o d u c t s . A n i n t e r e s t i n g q u e s t i o n o n e may a s k i s how g r e a t t h e a s y m m e t r i c i n f l u e n c e o f t h e c r y s t a l l a t t i c e w i l l b e o n t h e a s y m m e t r i c i n d u c t i o n o f o r g a n i c r e a c t i o n s . S e v e r a l a s y m m e t r i c s y n t h e s e s w i t h h i g h o p t i c a l y i e l d s b y s o l i d s c a t e p h o t o r e a c t i o n s o f o r g a n i c c h i r a i c r y s t a l s h a v e b e e n a c h i e v e d i n r e c e n t y e a r s . 3 z , 3 6 j n p r e s e n t s t u d i e s , t h e m a g n i t u d e o f t h i s c r y s t a l a s y m m e t r i c i n f l u e n c e o n t h e a s y m m e t r i c i n d u c t i o n i s e x a m i n e d b y p e r f o r m i n g s o l i d s t a t e p h o t o c h e m i c a l r e a c t i o n s o f some d i b e n z o b a r r e l e n e c o m p o u n d s w i t h r e s o l v e d c h i r a i s u b s t i t u e n t s a t t h e 9 -p o s i t i o n o f d i b e n z o b a r r e l e n e d i e s t e r s . B y u s i n g o p t i c a l l y p u r e s t a r t i n g m a t e r i a l s , o n e i s g u a r a n t e e d t h a t t h e s u b s t r a t e s w i l l c r y s t a l l i z e i n c h i r a i s p a c e g r o u p s . T h e c h i r a i s u b s t i t u e n t s u n d e r i n v e s t i g a t i o n w e r e d e s i g n e d i n s u c h a way t h a t t h e y a r e f a r e n o u g h a w a y f r o m t h e r e a c t i o n c e n t e r s o t h a t t h e r e s h o u l d b e l i t t l e o r n o a s y m m e t r i c i n d u c t i o n i n s o l u t i o n . T h e r e f o r e , a n y a s y m m e t r i c i n d u c t i o n o b s e r v e d i n t h e s o l i d s t a t e c a n b e a t t r i b u t e d t o t h e e f f e c t o f t h e c h i r a i c r y s t a l l a t t i c e . A . S t u d i e s o n 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e V i n y l M o n o e s t e r s - 90 -In h i s early studies of the di-n--me thane photorearrangement of dibenzobarrelene compounds, Ciganek"^ showed that v i n y l substituted dibenzobarrelene monoester 132 (R = CH3) underwent t r i p l e t photorearrangement with complete r e g i o s e l e c t i v i t y to give dibenzosemibullvalene product 134 (R = CH3) having the methyl ester group at the 8c-position (Scheme 41). Similar r e s u l t s were also found by C r i s t o l ^ i n the case of compound 132 where R = CH2CH3. This r e g i o s p e c i f i c reaction has been interpreted i n terms of the favoured odd-electron center s t a b i l i z a t i o n by the ester group on the proposed b i r a d i c a l intermediate 133. In contrast, i r r a d i a t i o n of the 9-substituted ester 137 was found"^ to give a 33:67 mixture of the two regioisomers, 139 and 141 (Scheme 42). This r e s u l t was interpreted by Zimmerman 4"^»^7 i n terms of d e s t a b i l i z a t i o n of the cyclopropane r i n g i n the b i r a d i c a l 138 leading to the isomer 139 by the electronegative ester group. Scheme 41 Phototransformation of Dibenzobarrelene 11-Ester. - 91 -S c h e m e 42 P h o t o t r a n s f o r m a t i o n o f M e t h y l 9 , 1 0 - D i h y d r o - 9 , 1 0 -E t h e n o a n t h r a c e n e - 9 - c a r b o x y l a t e . 78 R e c e n t l y , S c h e f f e r a n d c o - w o r k e r s h a v e d e m o n s t r a t e d t h a t d i b e n z o b a r r e l e n e 9 , 1 1 - d i e s t e r s 142 c a n u n d e r g o s m o o t h d i - 7 r - m e t h a n e r e a r r a n g e m e n t s i n t h e s o l i d s t a t e a s w e l l a s i n s o l u t i o n . D i r e c t i r r a d i a t i o n o f 142 i n b o t h m e d i a g a v e t h e c o r r e s p o n d i n g d i b e n z o s e m i b u l l v a l e n e s 143 a s t h e m a j o r p r o d u c t s a n d a l s o s m a l l a m o u n t s o f d i b e n z o c y c l o o c t a t e t r a e n e d e r i v a t i v e s 144 ( S c h e m e 4 3 ) . I n c o n t r a s t , t r i p l e t - s e n s i t i z e d p h o t o l y s i s o f 142 g a v e n o 1 4 4 , i n d i c a t i n g t h a t t h e f o r m a t i o n o f 144 was s i n g l e t - d e r i v e d . B y a t t a c h i n g r e s o l v e d c h i r a i g r o u p s a t t h e 9 - p o s i t i o n o f t h e d i b e n z o b a r r e l e n e s k e l e t o n , w h i c h d i r e c t s t h e c o m p o u n d s t o c r y s t a l l i z e i n 78 c h i r a i s p a c e g r o u p s , t h e a u t h o r s o b s e r v e d a s t r o n g l y r e v e r s e d 92 d i a s t e r e o s e l e c t i v e p h o t o t r a n s f o r m a t i o n i n t h e s o l i d s t a t e c o m p a r e d t o s o l u t i o n f o r c o m p o u n d 1 4 2 a . I n c o n t r a s t , t h e p h o t o r e a c t i o n o f 1 4 2 b was f o u n d t o b e n o n - d i a s t e r e o s e l e c t i v e i n b o t h c r y s t a l l i n e a n d s o l u t i o n p h a s e s . E 142 143 E 144 a | E = C 0 2 M e ; E ' = C 0 2 ( - ) - m e n t h y l b ) E = C 0 2 ( - ) - m e n t h y l ; E ' = C 0 2 M e S c h e m e 43 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e 9 , 1 1 - D i e s t e r s . A s o u r e f f o r t s i n s t u d y i n g t h e s o l i d s t a t e a s y m m e t r i c i n d u c t i o n c o n t i n u e , some o t h e r d i b e n z o b a r r e l e n e d e r i v a t i v e s w i t h r e s o l v e d c h i r a i h a n d l e s a t t h e b r i d g e h e a d p o s i t i o n w e r e p r e p a r e d , a n d t h e c h i r a i c r y s t a l l a t t i c e e f f e c t o n t h e d i a s t e r e o s e l e c t i v i t y o f t h e s e c o m p o u n d s was e x a m i n e d i n t h i s t h e s i s . 1 . P h o t o c h e m i s t r y o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e V i n y l M o n o e s t e r s 99 a n d 100 - 93 9 , 1 1 - D i s u b s t i t u t e d d i b e n z o b a r r e l e n e 99 a n d 9 , 1 2 - d i s u b s t i t u t e d d i b e n z o b a r r e l e n e 100 w e r e p r e p a r e d i n b o t h r a c e m i c a n d o p t i c a l l y a c t i v e f o r m s . D i r e c t a n d a c e t o n e - s e n s i t i z e d p h o t o l y s i s o f c o m p o u n d 9 9 , e i t h e r ( ± ) - 9 9 o r ( R ) - ( - ) - 9 9 , w a s f i r s t c a r r i e d o u t i n s o l u t i o n . A s e x p e c t e d , a s i n g l e r e g i o i s o m e r 145 w a s f o r m e d ( S c h e m e 44). "^H NMR a n a l y s i s i n d i c a t e d t h a t two d i a s t e r e o m e r s w e r e p r o d u c e d i n n e a r l y e q u a l a m o u n t s ( F i g u r e 1 1 ) . S t r u c t u r a l a s s i g n m e n t o f t h e p h o t o p r o d u c t w a s b a s e d p r i m a r i l y o n t h e w e l l k n o w n m e c h a n i s m i n v o l v e d i n s u c h p h o t o c h e m i c a l t r a n s f o r m a t i o n s a n d a l s o o n t h e s p e c t r o s c o p i c d a t a . T h e "^H NMR s p e c t r u m ( F i g u r e 1 1 ) w a s f o u n d t o b e i n a g r e e m e n t w i t h t h e a s s i g n m e n t . T h e c y c l o p r o p y l m e t h i n e p r o t o n r e s o n a t e s a t S = 3 . 7 5 ppm f o r o n e d i a s t e r e o m e r a n d a t 5 — 3 . 7 6 ppm f o r t h e o t h e r . T h e b e n z y l i c p r o t o n s f r o m t h e two d i a s t e r e o m e r s w e r e f o u n d a t 5 = 4 .99 a n d 5 . 0 1 p p m . A n o t h e r o b s e r v a t i o n i n t h e d i r e c t i r r a d i a t i o n o f 99 was t h a t t h e s i n g l e t - d e r i v e d d i b e n z o c y c l o o c t a t e t r a e n e d e r i v a t i v e was n o t f o r m e d . P h o t o l y s i s o f t h e c r y s t a l s o f 99 g a v e t h e s a m e p r o d u c t s a s t h o s e f o r m e d i n s o l u t i o n . S c h e m e 44 P h o t o l y s i s o f 9 , 1 1 - D i s u b s t i t u t e d D i b e n z o b a r r e l e n e 9 9 . 94 -I n c o n t r a s t , d i r e c t o r a c e t o n e - s e n s i t i z e d i r r a d i a t i o n o f r a c e m i c 9 , 1 2 - d i s u b s t i t u t e d 9 , 1 0 - e t h e n o a n t h r a c e n e 100 a f f o r d e d 146 a s t h e o n l y p h o t o p r o d u c t i n s o l u t i o n a n d i n t h e s o l i d s t a t e ( S c h e m e 4 5 ) . T h e a s s i g n m e n t o f t h e s t r u c t u r e was a l s o b a s e d o n t h e w e l l e s t a b l i s h e d m e c h a n i s m a n d s u p p o r t e d b y t h e s p e c t r o s c o p i c a n a l y s e s . T h e s t r u c t u r e o f 146 i s c h a r a c t e r i z e d i n t h e ^"H NMR s p e c t r u m b y a n A B q u a r t e t w h i c h i s - 95 -a t t r i b u t e d t o t h e n o n - e q u i v a l e n t c y c l o p r o p y l p r o t o n s ( C H - C H ) . I t c a n b e n o t e d t h a t n o new c h i r a i c e n t e r i s g e n e r a t e d i n t h e p r o d u c t 146, t h u s a s y m m e t r i c i n d u c t i o n was n o t e x a m i n e d i n t h i s c a s e . S c h e m e 45 P h o t o t r a n s f o r m a t i o n o f 9 , 1 2 - D i s u b s t i t u t e d D i b e n z o b a r r e l e n e 100 . 2 . R e s u l t s o n D i a s t e r e o s e l e c t i v i t y i n t h e S o l i d S t a t e v s S o l u t i o n T h e r e s u l t s f r o m t h e d e t e r m i n a t i o n o f t h e r e a c t i o n d i a s t e r e o s e l e c t i v i t y o f s u b s t r a t e 99 a r e p r e s e n t e d i n T a b l e 8. T h e d i a s t e r e o m e r i c r a t i o s w e r e d e t e r m i n e d b y . i n t e g r a t i o n o f t h e c o r r e s p o n d i n g b e n z y l i c p r o t o n s i g n a l s f o r t h e two d i a s t e r e o m e r s ( F i g u r e 11) . T h e m e a s u r e m e n t was a l s o c h e c k e d b y i n t e g r a t i o n o f a s e c o n d p a i r o f t h e r e s o n a n c e f o r t h e m e t h y l e n e p r o t o n s (CH2OCO). F i r s t , a n i n t e r e s t i n g o b s e r v a t i o n d r a w n f r o m t h e T a b l e i s t h a t t h e s o l u t i o n p h a s e p h o t o l y s i s o f o p t i c a l l y a c t i v e 99 g a v e n e a r l y n o d i a s t e r e o s e l e c t i v i t y ( d i a s t e r e o m e r 96 -r a t i o = 5 3 : 4 7 , w h i c h i s w i t h i n t h e e x p e r i m e n t a l e r r o r ) . I n c o n t r a s t , a h i g h e r d i a s t e r e o m e r i c r a t i o ( 3 8 : 6 2 ) w a s o b t a i n e d i n t h e s o l i d s t a t e r e a c t i o n . A p p a r e n t l y , t h e c h i r a l c e n t e r i s s i t u a t e d f a r e n o u g h a w a y f r o m t h e r e a c t i o n s i t e s o t h a t i t e x e r t s l i t t l e d i s y m m e t r i c i n f l u e n c e o n t h e i n i t i a l b e n z o - v i n y l b r i d g i n g i n s o l u t i o n . I n t h e s o l i d s t a t e , o n t h e o t h e r h a n d , t h e h i g h e r d i a s t e r e o s e l e c t i v i t y c a n b e a t t r i b u t e d g e n e r a l l y t o t h e i n f l u e n c e o f t h e c r y s t a l l a t t i c e . H o w e v e r , i t c a n b e a l s o s e e n f r o m T a b l e 8 t h a t t h e r a c e m i c c o m p o u n d 99 g a v e t h e s a m e d i a s t e r e o s e l e c t i v i t y i n t h e s o l i d s t a t e . A l t h o u g h t h e m o l e c u l a r c r y s t a l s t r u c t u r e s o f b o t h r a c e m i c a n d o p t i c a l l y a c t i v e 99 a r e n o t y e t a v a i l a b l e , t h e r e s u l t s s e e m t o i m p l y t h a t p r i m a r i l y a n e n v i r o n m e n t a l r a t h e r t h a n a m o l e c u l a r e f f e c t c o n t r o l s t h e d i a s t e r e o s e l e c t i v i t y o f t h e p h o t o t r a n s f o r m a t i o n o f 9 9 . T a b l e 8 Summary o n t h e R e a c t i o n D i a s t e r e o s e l e c t i v i t y o f 9 9 . a C o m p o u n d M e d i u m C o n v e r s i o n (%) D i a s t e r e o m e r R a t i o ( 1 4 5 ) ( ± ) - 9 9 s o l u t i o n 99 5 2 : 4 8 ( ± ) - 9 9 c r y s t a l 10 3 9 : 6 1 ( R ) - ( - ) - 9 9 s o l u t i o n 95 5 3 : 4 7 ( R ) - ( - ) - 9 9 c r y s t a l 10 3 8 : 6 2 a A n a l y s i s b y 1 H NMR. 97 B . S t u d i e s o n 9 , 1 0 - E t h e n o a n t h r a c e n e D i e s t e r s w i t h R e s o l v e d C h i r a i H a n d l e s a t t h e 9 - P o s i t i o n 1. P h o t o c h e m i s t r y T h e p h o t o c h e m i s t r y o f t h e d i b e n z o b a r r e l e n e d i e s t e r s 93a a n d 93b i s s i m i l a r t o t h e a c h i r a l c o m p o u n d 93c, w h i c h w a s d i s c u s s e d p r e v i o u s l y ( S c h e m e 37 o n p a g e 79) . I r r a d i a t i o n o f b o t h r a c e m i c a n d o p t i c a l l y a c t i v e 93a,b i n s o l u t i o n a s w e l l a s i n t h e s o l i d s t a t e l e d t o t h e f o r m a t i o n o f two r e g i o i s o m e r i c d i b e n z o s e m i b u l l v a l e n e d e r i v a t i v e s 1 4 7 a n d 148 ( S c h e m e 4 6 ) . A s e x p e c t e d , e a c h r e g i o i s o m e r c o n s i s t s o f two d i a s t e r e o m e r s . T h e r e a c t i o n m i x t u r e f r o m t h e p h o t o l y s e s o f t h e s e c o m p o u n d s p r o v e d d i f f i c u l t t o s e p a r a t e . T h e r e f o r e , i d e n t i f i c a t i o n a n d q u a n t i f i c a t i o n o f t h e p h o t o p r o d u c t s ( r e g i o i s o m e r s a n d d i a s t e r e o m e r s ) w e r e b a s e d p r i m a r i l y o n •*-H NMR s p e c t r o s c o p y ( S e c t i o n I V . B . 2 . ) . S c h e m e 46 P h o t o t r a n s f o r m a t i o n o f D i b e n z o b a r r e l e n e D i e s t e r s w i t h 9-R e s o l v e d C h i r a i H a n d l e s . - 98 -2 . R e s u l t s o n t h e R e g i o - a n d D l a s t e r e o s e l e c t i v i t i e s F o r b o t h c o m p o u n d s 9 3 a a n d 9 3 b , p h o t o p r o d u c t 147 w a s t h e p r e d o m i n a n t r e g i o i s o m e r . T h i s p r o d u c t c o u l d b e d i f f e r e n t i a t e d f r o m i t s r e g i o i s o m e r 148 o n t h e b a s i s o f t h e c h e m i c a l s h i f t s o f t h e n o n - a r o m a t i c m e t h i n e p r o t o n s i n t h e NMR s p e c t r a ( F i g u r e s 12 a n d 1 3 ) . C y c l o p r o p y l m e t h i n e p r o t o n s s u c h a s t h o s e p r e s e n t i n 147 a r e t y p i c a l l y f o u n d a t 6 ~ 4 . 4 p p m , w h i l e t h e s i g n a l s d u e t o t h e b e n z y l i c m e t h i n e p r o t o n s o f 148 r e s o n a t e c h a r a c t e r i s t i c a l l y a t 5 = 5 .1 p p m . I n t e g r a t i o n o f t h e s e s i g n a l s g a v e t h e r a t i o s o f t h e two r e g i o i s o m e r s w h i c h a r e s u m m a r i z e d i n T a b l e 9 . E x p e r i m e n t a l l y , t h e c h e m i c a l s h i f t s o f t h e s e r e s o n a n c e s w e r e f o u n d t o b e s l i g h t l y d i f f e r e n t f o r e a c h d i a s t e r e o m e r . T h e r e f o r e , a n o t h e r i n t e g r a t i o n o f t h e s i g n a l s c o r r e s p o n d i n g t o t h e d i a s t e r e o m e r s p r o v i d e d t h e d i a s t e r e o s e l e c t i v i t i e s r e p o r t e d i n T a b l e 9 a s w e l l . I n e a c h c a s e , t h e d i a s t e r e o m e r r a t i o s w e r e a l s o c h e c k e d b y i n t e g r a t i o n o f a s e c o n d p a i r o f r e s o n a n c e s (-OCH3 f o r 9 3 a a n d -NHCOCH3 f o r 9 3 b ) a n d w e r e f o u n d t o b e i n a g r e e m e n t w i t h t h e f i r s t i n t e g r a t i o n . T h e r e s u l t s a r e r e p r o d u c i b l e t o ±5% f r o m r u n t o r u n . S e v e r a l i n t e r e s t i n g c o n c l u s i o n s c a n b e d r a w n f r o m t h e r e s u l t s p r e s e n t e d i n T a b l e 9 . F i r s t o f a l l i t c a n b e s e e n t h a t , i n g e n e r a l , r e g i o s e l e c t i v i t y i s s l i g h t l y l o w e r i n t h e s o l i d s t a t e t h a n i n s o l u t i o n f o r b o t h s u b s t r a t e s . S e c o n d l y , i t i s i n t e r e s t i n g t o f i n d t h a t d i a s t e r e o s e l e c t i v i t y v a r i e s w i t h r e a c t i o n m e d i u m a s w e l l a s w i t h t h e n a t u r e o f t h e s u b s t r a t e s . I n t h e c a s e o f c o m p o u n d 9 3 b , we s e e t h a t i r r a d i a t i o n o f t h e c h i r a l c r y s t a l s g a v e h i g h e r d i a s t e r e o s e l e c t i v i t y i n t h e f o r m a t i o n o f p r o d u c t 1 4 8 b , b u t n o t i n t h e r e g i o i s o m e r 1 4 7 b . I n 99 -c o n t r a s t , h o w e v e r , t h e d i a s t e r e o s e l e c t i v i t y o b s e r v e d f o r c o m p o u n d 9 3 a i s l e s s i n t h e s o l i d s t a t e ( 5 0 : 5 0 ) c o m p a r e d t o s o l u t i o n ( 6 8 : 3 2 ) . A n a t t r a c t i v e e x p l a n a t i o n f o r t h e v a r i a b i l i t y o f t h e d i a s t e r e o s e l e c t i v i t y r a t i o s i s t h a t t h e m o l e c u l a r a n d e n v i r o n m e n t a l e f f e c t s o f t h e c h i r a l s u b s t i t u e n t s may e i t h e r r e i n f o r c e o r o p p o s e o n e a n o t h e r i n t h e s o l i d s t a t e . D e p e n d i n g o n t h e i r r e l a t i v e m a g n i t u d e , o p p o s i n g e f f e c t s c o u l d l e a d t o e i t h e r r e d u c e d o r r e v e r s e d d i a s t e r e o s e l e c t i v i t y i n t h e s o l i d s t a t e c o m p a r e d t o s o l u t i o n . T a b l e 9 R e g i o - a n d D i a s t e r e o s e l e c t i v i t y i n t h e S o l i d S t a t e a n d S o l u t i o n . a  R e a c t a n t M e d i u m R e g i o s e l e c t i v i t y D i a s t e r e o m e r R a t i o s 1 4 7 : 1 4 8 147 148 ( S ) - ( + ) - 9 3 b S o l u t i o n 85 : 15 5 5 : 4 5 5 2 : 4 8 ( S ) - ( + ) - 9 3 b C r y s t a l 68 : 32 4 7 : 5 3 7 5 : 2 5 ( R ) - ( - ) - 9 3 a S o l u t i o n 90 : 10 6 7 : 3 3 6 8 : 3 2 ( R ) - ( - ) - 9 3 a C r y s t a l 80 : 20 6 1 : 3 9 5 0 : 5 0 a 1 A n a l y s i s b y H NMR. R a t i o s w e r e d e t e r m i n e d a t c o m p l e t e c o n v e r s i o n i n s o l u t i o n a n d < 50% i n t h e s o l i d s t a t e . 400 MHz F i g u r e 13 P a r t i a l H NMR S p e c t r u m o f R e a c t i o n M i x t u r e f r o m 9 3 a . - 102 -A conclusion that may be drawn from the above studies is that different chirai handles (substituents) may lead to different diastereoselectivity, both in the solid state and i n solution. In particular, even minor changes on the substituents may result in completely different molecular crystal packing pattern in the solid, thus, leading to different diastereoselectivity. The magnitude of the asymmetric induction depends uniquely on the crystal lattice forces. It is also apparent that the nature and location of the chirai handle in relation to the site of reaction has a strong influence on the diastereoselectivity observed. The two chirai handles examined in this thesis, i.e. N-acetyl-L-alanine ester and (R)-(-)-methoxyphenylacetic acid ester, are quite different in nature. Although the separation distances between the chirai centers and the reaction site are nearly the same, the diastereoselectivities for the two systems are quite different in solution as well as in the solid state. 3. Molecular Crystal Structure of Compound 93b and Its Photochemical Implications In general, the non-diastereoselectivity observed in the solution phase photolyses could be interpreted to be due to the remoteness and random orientation of the chirai handles in relation to the reaction centers, thus, the disymmetric influence of the chirai handles leading to diastereomeric transition states is small. One question, however, remains. That i s , how the disymmetric influence from the crystal lattice has a different effect on the diastereoselectivity of the two pathways - 103 ( p a t h A a n d p a t h B) . I n o t h e r w o r d s , p a t h B g i v e s h i g h e r d i a s t e r e o s e l e c t i v i t y i n t h e s o l i d s t a t e r e a c t i o n i n t h e c a s e o f c o m p o u n d 9 3 b , w h e r e a s p a t h A i s s u b s t a n t i a l l y n o n - d i a s t e r e o s e l e c t i v e . I n o r d e r t o u n d e r s t a n d s u c h d i f f e r e n c e s o n t h e r e a c t i o n d i a s t e r e o s e l e c t i v i t y i n t h e d u a l p a t h w a y s , t h e c r y s t a l s t r u c t u r e o f t h e m o l e c u l e 93b w a s d e t e r m i n e d . F i g u r e 1 4 s h o w s b o t h t h e m o l e c u l a r s t r u c t u r e a n d c r y s t a l p a c k i n g d i a g r a m s o f c o m p o u n d 9 3 b . F i g u r e 1 4 M o l e c u l a r C r y s t a l S t r u c t u r e a n d P a c k i n g D i a g r a m s o f C o m p o u n d 9 3 b . - 104 -C o m p o u n d 9 3 b i s f o u n d t o c r y s t a l l i z e i n t h e s p a c e g r o u p P2^2]_2T_, o n e o f t h e m o s t common c h i r a l s p a c e g r o u p s f o r o r g a n i c m o l e c u l e s . Two i m p o r t a n t f e a t u r e s a r e n o t e d i n t h e c r y s t a l s t r u c t u r e o f 93b, o n e b e i n g i n t r a m o l e c u l a r i n n a t u r e a n d t h e o t h e r i n t e r m o l e c u l a r . T h e s p e c i f i c m o l e c u l a r c o n f o r m a t i o n o f 93b i s s u c h t h a t t h e 1 1 - e s t e r c a r b o n y l g r o u p ( c r y s t a l s t r u c t u r e g i v e s t h e n u m b e r a s 1 2 - e s t e r g r o u p ) i s n e a r l y i n c o m p l e t e c o n j u g a t i o n . I n c o n t r a s t , t h e 1 2 - e s t e r c a r b o n y l ( c r y s t a l s t r u c t u r e g i v e s t h e n u m b e r a s 1 1 - e s t e r ) i s c o m p l e t e l y o u t o f c o n j u g a t i o n w i t h t h e v i n y l d o u b l e b o n d . I n t e r m o l e c u l a r l y , i t c a n b e n o t e d t h a t t h e h y d r o g e n a t o m o f t h e NH g r o u p i n o n e m o l e c u l e i s h y d r o g e n - b o n d e d t o t h e 1 2 - e s t e r c a r b o n y l o x y g e n a t o m o f t h e n e i g h b o r i n g m o l e c u l e ( F i g u r e 1 4 ) . T h e h y d r o g e n - b o n d i n g d i s t a n c e ( N - H - • - 0 = C ) i s f o u n d t o b e 2 . 2 2 A . T u r n i n g t o t h e i n t e r p r e t a t i o n o f t h e s o l i d s t a t e s t r u c t u r e -r e a c t i v i t y r e l a t i o n s h i p s f o r c o m p o u n d 93b, a s - m e n t i o n e d e a r l i e r , t h e r e g i o s e l e c t i v i t y ( p r o d u c t r a t i o o f 147:148) i n t h e s o l i d s t a t e r e a c t i o n d o e s n o t d i f f e r v e r y m u c h f r o m t h e s a m e r e a c t i o n i n t h e s o l u t i o n p h a s e . A p o s s i b l e e x p l a n a t i o n d r a w n f r o m t h e c r y s t a l s t r u c t u r e a n a l y s i s i s a s f o l l o w s . I t s e e m s t h a t t h e s t a b i l i z a t i o n e f f e c t d e t e r m i n e d b y t h e d e g r e e o f c o n j u g a t i o n o f t h e c a r b o n y l g r o u p o n t h e i n i t i a l l y f o r m e d r a d i c a l i n t e r m e d i a t e s p e c i e s w o u l d f a v o r t h e b e n z o - v i n y l b r i d g i n g o n t h e s i d e o f t h e 9 - s u b s t i t u e n t . T h u s , m o r e p h o t o p r o d u c t 148b w a s f o r m e d i n t h e s o l i d s t a t e (147b:148b - 6 8 : 3 2 ) c o m p a r e d t o s o l u t i o n (147b:148b = 8 5 : 1 5 ) . T h e r e s u l t s a r e i n a g r e e m e n t w i t h s u c h e l e c t r o n i c s t a b i l i z i n g a r g u m e n t , b u t o n e t h i n g s h o u l d b e p o i n t e d o u t . A s d i s c u s s e d p r e v i o u s l y i n t h e t h e s i s , t h e s t e r i c e f f e c t s f r o m t h e c r y s t a l l a t t i c e c o u l d a l s o b e t h e k e y f a c t o r s t h a t c o n t r o l t h e r e g i o s e l e c t i v i t y i n t h e d i - 7 r - m e t h a n e - 105 -photorearrangement. In the case of compound 93b, the intermolecular hydrogen bonding effect (N-H-•-0=C) might be important. We considered that the benzo-vinyl bridging from the 12-vinyl carbon atom would result in motions of the ester group that is attached on the 12-vinyl carbon atom. However, the carbonyl oxygen atom of this ester group is hydrogen-bonded to the NH group of the neighboring molecule. Such hydrogen bonding might hinder the movement of the ester group in space, and consequently diminish the reaction. Based on such assumption, therefore, the electronic stabilizing effect and the crystal lattice steric effect exert their influences in opposite directions Hydrogen-bonding effects on di-7r-methane regioselectivity have 79 been studied in our laboratory. One interesting example is given below (Scheme 47). Photochemical transformation of acid-ester 149 in the solid state was found to be very different from i t s counterpart in solution. In dilute benzene, photoproduct 150 predominated (150:151 = 83:17), but in the crystalline state there was a nearly complete preference for the formation of regioisomer 151 (150:151 = 5:95). This was attributed to a difference in hydrogen bonding that exists in solution and in the crystal. Under the situation of intramolecular hydrogen bonding in dilute solution, formation of photoproduct 150 was favorable, which was interpreted as being due to development of partial positive charge on the carboxylic acid-bearing vinyl carbon atom as a result of internal proton transfer to the carbonyl oxygen atom of the ester group. In the crystal, i t was demonstrated that there was strong intermolecular hydrogen bonding between carboxylic acid groups. For this reason, the authors suggested that hydrogen bonding "anchors" the carboxylic acid group and hinders the motions necessary for i n i t i a l bonding at the vinyl 106 c a r b o n a t o m t o w h i c h t h e c a r b o x y l i c a c i d g r o u p i s a t t a c h e d . A s a r e s u l t , b o n d i n g a t t h e o t h e r v i n y l c a r b o n a t o m a n d f o r m a t i o n o f t h e p h o t o p r o d u c t 1 5 1 i s t h e m o s t f a v o r e d i n t h e c r y s t a l . COOH ROOC 149 COOH ICOOR R=iPr 150 COOR I COOH 151 S c h e m e 47 D i - 7 r r M e t h a n e P h o t o r e a r r a n g e m e n t o f A c i d - E s t e r 1 4 9 . A s p e c u l a t i o n o n t h e s o l i d s t a t e d i a s t e r e o s e l e c t i v i t y o f c o m p o u n d 9 3 b may a l s o b e d r a w n f r o m t h e c r y s t a l s t r u c t u r e a n a l y s i s . I t c a n b e n o t e d t h a t t h e two b e n z o - v i n y l b r i d g i n g s i n p a t h B m e c h a n i s m ( F i g u r e 15) e x p e r i e n c e d i f f e r e n t s p a t i a l e n v i r o n m e n t o w i n g t o t h e s p e c i f i c i n t e r m o l e c u l a r c o n t a c t i n t h e c r y s t a l . O n t h e s i d e o f t h e i n i t i a l b r i d g i n g B ( I I ) , t h e c a r b o n y l o x y g e n a t o m o f t h e 1 2 - e s t e r g r o u p i s h y d r o g e n - b o n d e d b y t h e NH g r o u p , a n d I n a d d i t i o n , t h e s p a c e i s r e l a t i v e l y b l o c k e d b y t h e m e t h y l g r o u p f r o m t h e n e i g h b o r i n g m o l e c u l e . I n c o n t r a s t , t h e s p a c e o n t h e o t h e r s i d e ( i n i t i a l b r i d g i n g B ( I ) ) i s f r e e o f a n y i n t e r m o l e c u l a r c o n t a c t . B e c a u s e o f s u c h d i f f e r e n c e s i n t h e r e a c t i o n e n v i r o n m e n t , i t s e e m s t o b e t h a t t h e i n i t i a l b o n d i n g o n t h e l e s s h i n d e r e d s i d e l e a d i n g t o o n e o f t h e d i a s t e r e o m e r s ( p a t h B ( I ) ) i s p r e f e r r e d o v e r t h e o t h e r . B u t , i t i s n o t a b s o l u t e l y k n o w n a s t o w h i c h - 107 p a r t i c u l a r i n i t i a l b r i d g i n g g i v e s t h e p r e f e r r e d d i a s t e r e o m e r i n t h e s o l i d s t a t e p h o t o l y s i s . F u r t h e r m o r e , i t i s a p p a r e n t b y v i e w i n g t h e c r y s t a l p a c k i n g d i a g r a m ( F i g u r e 1 4 ) t h a t t h e i n i t i a l b e n z o - v i n y l b r i d g i n g a t t h e C - l l c a r b o n a t o m ( c r y s t a l s t r u c t u r e g i v e s t h e n u m b e r a s C - 1 2 ) , w h i c h i s o n t h e u n s u b s t i t u t e d s i d e o f t h e d i b e n z o b a r r e l e n e s k e l e t o n , i s r e l a t i v e l y f r e e o f a n y s t e r i c i n f l u e n c e f r o m t h e c r y s t a l l a t t i c e . I n a d d i t i o n , t h e r e a c t i o n s i t e i s s e p a r a t e d f r o m t h e c h i r a i c e n t e r s b o t h i n t r a m o l e c u l a r l y a n d i n t e r m o l e c u l a r l y . T h i s m i g h t a c c o u n t f o r t h e o b s e r v a t i o n t h a t t h e t r a n s f o r m a t i o n v i a p a t h A i n t h e s o l i d s t a t e i s n o n - d i a s t e r e o s e l e c t i v e . F i g u r e 15 S t e r i c E f f e c t i n t h e P h o t o r e a r r a n g e m e n t o f 9 - S u b s t i t u t e d D i b e n z o b a r r e l e n e D i e s t e r 9 3 b via P a t h B M e c h a n i s m . - 108 -V. Studies on the Photoreactivity and Selectivity of Dibenzobarrelene Lactones As discussed in the section dealing with the preparation of the starting materials, an earlier attempt to synthesize 9-hydroxymethyl-9,10-ethenoanthracene 95 by the Diels-Alder addition of dimethyl acetylenedicarboxylate to 9-anthracenemethanol resulted in the lactone-ester 96 (Scheme 22 on page 43). Photolysis of this compound in solution and in the solid state provided some interesting results in terms of photochemical reactivity and product regioselectivity. This led us logically to the preparation of some other similar lactone derivatives such as compounds 97 and 98. Photochemical studies on these substrates are included in this part. A. Photochemical Studies on Dibenzobarrelene Lactone-Ester 96 1. Photochemistry of Lactone-Ester 96 As can be recognized, the ground state electronic structure of the lactone-ester 96 is much the same as that of i t s analogue compound 93c, which can be considered to be the ring-opened form of the lactone-ester 96. The photochemistry of dibenzobarrelene 93c has been discussed in a previous part of this thesis in which i t was shown that photolysis of compound 93c gave predominantly 4b-acetoxymethyl dibenzosemibullvalene 120 both in solution and crystalline phase (Scheme 48). In a similar fashion, the lactone-ester 96 was expected to be capable of giving two regioisomeric di-7r-methane photoproducts, 152 and 153 (Scheme 48) upon irradiation. It was also expected that the photoreaction of compound 96 would produce the rearranged polycyclic lactone 152 (4b-isomer) via path - 109 A as the major photoproduct based on the genera l obse rva t ions o f a 51 52 number o f 9 - s u b s t i t u t e d 9,10-ethenoanthracenes. ' E x p e r i m e n t a l l y , however, d i r e c t or a c e t o n e - s e n s i t i z e d p h o t o l y s i s o f the l a c t o n e - e s t e r 96 i n s o l u t i o n a f fo rded compound 153 (8b-isomer) e x c l u s i v e l y ; no t r ace o f 152 c o u l d be de tec ted by GC or NMR. In c o n t r a s t , i r r a d i a t i o n o f c r y s t a l s o f 96 gave both photoproducts , 152 and 153, i n a r a t i o o f 13:87 . A g a i n , the s o l u t i o n photoproduct 153 i s predominant. Th i s unusual r e s u l t i n the di-7r-methane r e a c t i o n o f 96 (compared to the pho to t r ans fo rma t ion o f compound 93c) l e d us to the q u e s t i o n why the r e g i o s e l e c t i v i t y i s comple te ly reversed i n t h i s case . D a t h A ^ - " " ^ \ = / h u path B 120 CH20Ac m a j or 93c E = C02CH3 E. £ .CH20Ac 124 minor hu path A 152 96 153 r a t i o 152:153 s o l u t i o n 0:100 c r y s t a l 13:87 E = C O 2 C H 3 Scheme 48 Photochemical Trans fo rmat ions ,o f Lac tone -Es t e r 96 and I t s Analogue 93c. 110 -The structures of photoproducts 152 and 153 were established by spectroscopic analyses. The regiochemistry is assigned by "^H NMR spectroscopy; particularly informative are the chemical shifts of the non-aromatic methine protons. The cyclopropyl hydrogen atom in the 4b-substituted isomer 152 is found at 5 = 4.85 ppm; on the other hand, the benzylic methine proton of product 153 appears at 5 = 5.17 ppm. This 51 52 assignment is in agreement with the general trend ' for compounds of this type and was confirmed by the following independent synthesis of photoproduct 152. Reduction of the aldehyde derivative 118, which is 52 prepared by making use of the known 94-+118 phototransformation, gives the corresponding alcohol derivative 119. Acid-catalyzed cyclization of compound 119 yields the dibenzosemibullvalene lactone 152, which proved to be the same as the solid state photoproduct in the photolysis of compound 96 (Scheme 49). The structure of 153 is also supported by lactonization of the 8b-hydroxymethyl dibenzosemibullvalene 123. In a workup procedure to separate the photoproduct 123 from the photolysate of 95, i t was found that this material is unstable on s i l i c a gel column and underwent cyclization to produce the corresponding lactone, derivative 153. This, in turn, confirms the structure of 123 as discussed in section III.B.l. - I l l 153 S c h e m e 49 I n d e p e n d e n t P r e p a r a t i o n o f P h o t o p r o d u c t s 152 a n d 1 5 3 . 2 . I n t e r p r e t a t i o n o n t h e R e a c t i o n R e g i o s e l e c t i v i t y o f 96 i n S o l u t i o n T h e r e g i o s e l e c t i v i t y o b s e r v e d i n t h e d i - 7 r - m e t h a n e p h o t o -r e a r r a n g e m e n t o f t h e l a c t o n e - e s t e r 96 i s u n u s u a l i n t h a t t h e p h o t o -- 112 -t r a n s f o r m a t i o n o f 96 p r o c e e d s v i a p a t h B e x c l u s i v e l y c o m p a r e d t o t h e a n a l o g u e 9 3 c , w h i c h a f f o r d s t h e d i b e n z o s e m i b u l l v a l e n e 1 2 0 a s t h e m a j o r p h o t o p r o d u c t v i a p a t h A . O n e r e l a t e d e x a m p l e i n t h e l i t e r a t u r e i s t h e p h o t o r e a r r a n g e m e n t o f 80 d i b e n z o b a r r e l e n e l a c t a m d e r i v a t i v e 1 5 4 ( S c h e m e 5 0 ) . C i g a n e k d e m o n s t r a t e d t h a t d i r e c t i r r a d i a t i o n o f t h e l a c t a m 1 5 4 i n T H F y i e l d e d f u s e d d i b e n z o c y c l o o c t a t e t r a e n e 1 5 5 , w h i c h w a s c o n s i d e r e d t o b e a s i n g l e t - d e r i v e d p r o d u c t . I n c o n t r a s t , a c e t o n e - s e n s i t i z e d ( t r i p l e t ) r e a c t i o n i n v o l v e d t h e d i - ? r - m e t h a n e r e a c t i o n t o g i v e p r o d u c t s 156 a n d 1 5 7 . I t w a s f o u n d t h a t t h e r e a r r a n g e m e n t p r o c e e d s v i a t h e p a t h w a y B p r e d o m i n a n t l y t o g i v e 157 a s t h e m a j o r p h o t o p r o d u c t . H o w e v e r , s u c h r e g i o s e l e c t i v i t y i n t h e d i - 7 r - m e t h a n e . r e a r r a n g e m e n t c o u l d n o t b e e x p l a i n e d b y t h e e l e c t r o n i c s t a b i l i z i n g e f f e c t , s i n c e o f t h e two i n i t i a l l y f o r m e d b i r a d i c a l s p e c i e s , t h e d i t e r t i a r y b i r a d i c a l 158 s h o u l d b e f a v o r e d o v e r t h e t e r t i a r y / s e c o n d a r y b i r a d i c a l 1 5 9 . I n a d d i t i o n , t h e c y c l o p r o p a n e r i n g i n t h e . b i r a d i c a l 159 l e a d i n g t o t h e i s o m e r 157 m i g h t b e d e s t a b i l i z e d b y t h e e l e t r o n e g a t i v e a m i d e g r o u p , w h i c h w a s p r o p o s e d b y Z i m m e r m a n ' a s a p o s s i b l e r e a s o n f o r t h e r e g i o s e l e c t i v i t y i n t h e c a s e o f m e t h y l 9 , 1 0 - e t h e n o a n t h r a c e n e - 9 - c a r b o x y l a t e ( S c h e m e 4 2 o n p a g e 9 1 ) . T h e s e a r g u m e n t s w o u l d f a v o r f o r m a t i o n o f b i r a d i c a l 1 5 8 , w h e r e a s i n f a c t t h e r e a r r a n g e m e n t p r o c e e d s p r e d o m i n a n t l y t h r o u g h b i r a d i c a l 1 5 9 . H o w e v e r , n o e x p l a n a t i o n was s u g g e s t e d . - 113 -I n a n o t h e r e x a m p l e , C i g a n e k s h o w e d t h a t a c e t o n e - s e n s i t i z e d i r r a d i a t i o n o f d i b e n z o b a r r e l e n e a m i n e d e r i v a t i v e 1 6 0 f o r m e d r e g i o i s o m e r s 162 a n d 1 6 4 ( S c h e m e 5 1 ) . I n t h i s c a s e , t h e e l e c t r o n i c s t a b i l i z i n g e f f e c t w a s f o l l o w e d , i n w h i c h t h e m a j o r p h o t o p r o d u c t 162 was f o r m e d v i a t h e m o r e s t a b l e b i r a d i c a l i n t e r m e d i a t e 1 6 1 . 114 164 Scheme 51 Di-7r-methane Photorearrangement of Dibenzobarrelene Amine Derivative 160. By comparison, the lactone-ester 96 studied in the present work shows different regioselectivity towards the di-7r-methane reaction from the triester 93c. The proposed electronic stabilizing effect is also incompatible with the results. This is because the two biradical intermediates 165 and 166 from pathways A and B would be considered to be equally stabilized through conjugation by the carbonyl groups from the ester or the lactone (Scheme 52) , but the cyclopropyl ring in the biradical 166 might be destabilized by the 9-alkyl group (electron-donating group), and this would disfavor the formation of biradical 166. 115 -0 166 S c h e m e 52 B i r a d i c a l I n t e r m e d i a t e s i n P h o t o r e a r r a n g e m e n t o f L a c t o n e -E s t e r 9 6 . We h a v e s u g g e s t e d t h a t a n i n t r a m o l e c u l a r s t e r i c e f f e c t may b e r e s p o n s i b l e f o r s u c h r e v e r s e d r e g i o s e l e c t i v i t y i n t h e d i - 7 r - m e t h a n e r e a c t i o n o f t h e l a c t o n e - e s t e r 9 6 . T h i s c o m e s f r o m t h e r e a l i z a t i o n t h a t t h e c o n f o r m a t i o n a l l y r i g i d f i v e - m e m b e r e d l a c t o n e i s s t e r i c a l l y h i n d e r e d . M o l e c u l a r m o d e l s s h o w t h a t f a i r l y s e v e r e s t e r i c i n t e r a c t i o n s a r e p r e s e n t b e t w e e n t h e m e t h y l e n e h y d r o g e n a t o m s o f t h e l a c t o n e r i n g a n d t h e a d j a c e n t a r o m a t i c h y d r o g e n a t o m s ( F i g u r e 1 6 ) . A s h o r t c o n t a c t b e t w e e n t h e two k i n d s o f h y d r o g e n a t o m s w a s f i r s t c o n f i r m e d b y a n NOE e x p e r i m e n t o f "^H NMR s p e c t r o s c o p y ( F i g u r e 1 7 ) , i n w h i c h i r r a d i a t i o n o f t h e a d j a c e n t a r o m a t i c p r o t o n s r e s u l t e d i n a s i g n a l e n h a n c e m e n t o f t h e m e t h y l e n e p r o t o n s . I n a l a t e r c r y s t a l l o g r a p h i c s t u d y o n t h e m o l e c u l a r c r y s t a l s t r u c t u r e o f l a c t o n e - e s t e r 9 6 , i t i s f o u n d t h a t t h e c o n c e r n e d H - - -H d i s t a n c e s a r e s t a r t l i n g l y s h o r t , 2 .06 A • o n o n e s i d e a n d a l e s s s e v e r e - 1 1 6 i n t e r a c t i o n o f 2 . 4 3 A o n t h e o t h e r . T h e s t e r e o d i a g r a m o f m o l e c u l e 96 i s g i v e n i n F i g u r e 1 8 . I n s o l u t i o n , t h e H - • - H c o n t a c t s w i l l a v e r a g e t o a p p r o x i m a t e l y 2 . 0 6 / 2 + 2 . 4 3 / 2 = 2 . 2 5 A , w h i c h i s w e l l b e l o w 2 . 4 0 A , t h e sum o f t h e c o m m o n l y a c c e p t e d v a n d e r W a a l s r a d i u s o f 1 . 2 0 A f o r 82 h y d r o g e n . T o h e l p t o u n d e r s t a n d s u c h s t e r i c e f f e c t , two i n i t i a l b e n z o - v i n y l b r i d g i n g s f o r c o m p o u n d 96 a r e p r e s e n t e d i n F i g u r e 1 6 . a-x/a-x' b o n d i n g c o r r e s p o n d s t o t h e f o r m a t i o n o f 4 b - i s o m e r 152 a n d b - y / b - y ' b r i d g i n g l e a d s t o t h e 8 b - i s o m e r 1 5 3 . M o l e c u l a r m o d e l s t u d i e s r e v e a l t h a t p a t h w a y s b - y a n d b - y ' l e a d i n g t o p r o d u c t 153 c a n r e l i e v e t h e H- • -H s t e r i c i n t e r a c t i o n s t o a m u c h g r e a t e r e x t e n t t h a n p a t h w a y s a-x a n d a-x'; t h e l a t t e r p a t h w a y s ( p a t h A) a f f o r d 152 w i t h t h e u n f a v o r a b l e H - • - H i n t e r a c t i o n s b a s i c a l l y i n t a c t . T h e r e f o r e , p a t h B (a-x a n d a-x' b o n d i n g ) i s s u g g e s t e d t o b e f a v o r e d k i n e t i c a l l y . F i g u r e 16 M o l e c u l a r S t r u c t u r e o f L a c t o n e - E s t e r 96 S h o w i n g H-C o n t a c t s . • H 117 -P a r t i a l H NMR Spectra of Lactone-Ester 96. Top and middle: NOE difference a f t e r i r r a d i a t i o n . Bottom: without i r r a d i a t i o n . - 118 Figure 18 Stereodiagram of Compound 96. 3. Absolute Asymmetric Synthesis v i a Photoreaction of C h i r a l Crystals of Lactone-Ester 96 Absolute asymmetric synthesis r e f e r s to an asymmetric synthesis c a r r i e d out i n a closed system i n the absence of any external c h i r a l 31 influence. I t i s a process unique to c r y s t a l l i n e phase reactions. Such a process involves the f i r s t stage of spontaneous c r y s t a l l i z a t i o n of an a c h i r a l molecule in a c h i r a l space group, and then o p t i c a l l y active product(s) is(are) generated during the second stage, which consists of a chemical reaction that transforms the c r y s t a l c h i r a l i t y into permanent - 119 m o l e c u l a r c h i r a l i t y . T h e a s y m m e t r i c i n d u c t i o n c o m e s d i r e c t l y f r o m t h e a s y m m e t r i c c r y s t a l l i n e m a t r i x . A c h i r a l o r g a n i c m o l e c u l e s t h a t c r y s t a l l i z e i n c h i r a l s p a c e g r o u p s c a n b e c l a s s i f i e d i n two g e n e r a l c a t e g o r i e s a c c o r d i n g t o t h e i r l i q u i d 83 p h a s e c o n f o r m a t i o n a l c h a r a c t e r i s t i c s : ( 1 ) f l e x i b l e m o l e c u l e s t h a t a d o p t c h i r a l c o n f o r m a t i o n s d u e t o s p e c i f i c m o l e c u l a r a r r a n g e m e n t s i n t h e s o l i d s t a t e , w h i l e m a i n t a i n i n g a n a v e r a g e s y m m e t r y t h r o u g h f a s t c o n f o r m a t i o n a l c h a n g e s i n s o l u t i o n ; a n d ( 2 ) r i g i d m o l e c u l e s t h a t c a n n o t c o n t r i b u t e t o s i g n i f i c a n t c h i r a l c o n f o r m a t i o n s i n s o l u t i o n o r i n t h e s o l i d s t a t e e x c e p t f o r m i n o r d e f o r m a t i o n s . T h e l a c t o n e - e s t e r 9 6 , w h i c h i s a c h i r a l , i s f o u n d t o c r y s t a l l i z e i n c h i r a l s p a c e g r o u p s ?2\l\l\ f r o m a c e t o n e / h e x a n e o r c h l o r o f o r m / m e t h a n o l . I t c a n n o t e d t h a t t h e l a c t o n e - e s t e r i s r e l a t i v e l y r i g i d o v e r a l l o w i n g t o t h e p o l y c y c l i c f u s e d r i n g s y s t e m , e x c e p t t h a t a c e r t a i n d e g r e e o f m o t i o n o f t h e v i n y l e s t e r g r o u p i s p o s s i b l e . T h e m o l e c u l a r c r y s t a l s t r u c t u r e o f 96 ( F i g u r e 1 8 ) s h o w s t h a t t h e c o n f o r m a t i o n o f 96 i n t h e s o l i d s t a t e m a i n t a i n s r o u g h l y a p l a n e o f s y m m e t r y . T h u s , t h e c h i r a l i t y o f t h e c r y s t a l s o f 96 may b e c o n s i d e r e d t o c o m e m a i n l y f r o m t h e d i s y m m e t r i c s p a t i a l a r r a n g e m e n t o f t h e m o l e c u l e s . A s y m m e t r i c i n d u c t i o n i n t h e f o r m a t i o n o f p h o t o p r o d u c t s 152 a n d 1 5 3 , i n t e r m s o f e n a n t i o m e r i c e x c e s s , was e x a m i n e d b o t h i n s o l u t i o n a n d i n t h e c r y s t a l l i n e p h a s e . T h e l a c t o n e - e s t e r 96 i n a c e t o n e w a s i r r a d i a t e d t o c o m p l e t i o n o n a p r e p a r a t i v e s c a l e . T h e s o l e p r o d u c t 152 w a s p u r i f i e d b y c r y s t a l l i z a t i o n a n d s h o w n t o b e o p t i c a l l y i n a c t i v e b y u s i n g t h e c h i r a l s h i f t r e a g e n t , 3 - ( h e p t a f l u o r o p r o p y l h y d r o x y m e t h y l e n e , d -1 2 0 c a m p h o r a t e ) - e u r o p i u m ( I I I ) ( a b b r e v i a t e d a s E u ( h f c ) 3 ) . T h e r e g i o i s o m e r 1 5 3 , w h i c h w a s n o t f o r m e d i n t h e s o l u t i o n p h o t o l y s i s , was i n d e p e n d e n t l y s y n t h e s i z e d a s s h o w n i n S c h e m e 4 9 . T h i s m a t e r i a l w a s o b t a i n e d a s a r a c e m i c m i x t u r e . S i n g l e c r y s t a l s o f 96 w e r e s e l e c t e d r a n d o m l y i n t h e e x p e r i m e n t a n d o n l y o n e s i n g l e c r y s t a l w i t h o r w i t h o u t s l i g h t c r u s h i n g was u s e d i n e a c h r u n . T h e s a m p l e s w e r e i r r a d i a t e d e i t h e r w i t h a m e r c u r y l a m p (A > 2 9 0 nm b y u s i n g a P y r e x f i l t e r ) o r a n i t r o g e n l a s e r (A = 337 nm) f o r 1 0 - 6 0 h r . T h e r e s u l t i n g c r y s t a l l i n e s o l i d s w e r e d i s s o l v e d i n CDCI3 a n d t h e n a n a l y z e d d i r e c t l y b y p o l a r i m e t r y t o d e t e r m i n e t h e s i g n a n d m a g n i t u d e o f o p t i c a l r o t a t i o n o f t h e r e a c t i o n m i x t u r e . F o l l o w i n g t h i s , t h e s a m e s a m p l e s w e r e a n a l y z e d b y ~H NMR w i t h t h e c h i r a i s h i f t r e a g e n t , E u ( h f c ) 3 . T h e o p t i c a l p u r i t i e s o f p h o t o p r o d u c t s 152 a n d 153 f r o m t h e s o l i d s t a t e i r r a d i a t i o n w e r e d e t e r m i n e d b y m o n i t o r i n g t h e m e t h y l s i n g l e t f r o m t h e e s t e r g r o u p i n e a c h c a s e . T h e r e s u l t s o b t a i n e d a r e s u m m a r i z e d i n T a b l e 1 0 . A t y p i c a l s e t o f "^H NMR s p e c t r a f o r t h e o p t i c a l a c t i v i t y a n a l y s i s o f t h e p h o t o p r o d u c t s i s g i v e n i n F i g u r e 1 9 . - 121 -T a b l e 10 A s y m m e t r i c I n d u c t i o n s i n t h e S o l i d S t a t e P h o t o r e a c t i o n o f L a c t o n e - E s t e r 9 6 . E x p e r . T e m p . CC) C o n v e r s i o n (%) S i g n o f R o t a t i o n E n a n t i o m e r i c 152(%) E x c e s s 3 153(%) T r i a l 1 20 >99 ( - ) 50 <2 T r i a l 2 22 74 ( - ) 66 0 T r i a l 3 22 68 ( - ) 61 <2 T r i a l 4 20 64 (+) 58 0 T r i a l 5 20 50 ( - ) 52 2 T r i a l 6 38 85 ( - ) 60 2 T r i a l 7 38 58 ( - ) 70 0 T r i a l 8 - 5 92 ( - ) 6 4 __b T r i a l 9 - 5 34 ( - ) 63 _ j b T r i a l 10 - 2 0 52 ( - ) 1 0 0 0 T r i a l 11 - 2 0 39 ( + ) 74 0 T r i a l 12 - 2 0 34 ( + ) 70 0 T r i a l 13 - 2 0 17 ( - ) 1 0 0 c 0 S o l u t i o n 20 100 0 0 a D e t e r m i n e d b y i n t e g r a t i o n o f t h e c o r r e s p o n d i n g s p l i t s i g n a l s , u s i n g E u ( h f c ) 3 , e s t i m a t e d 3% e r r o r a c c o r d i n g t o r e f e r e n c e 8 4 . b N o t m e a s u r e d . c E s t i m a t e d 10% e r r o r d u e t o t h e w e a k s i g n a l s a t l o w c o n v e r s i o n . - 122 -Photoproducts 152 and 153 6 . 0 A ) J LL 5 . 0 400 MHz 4 . 0 PPM — i — 3 . 0 F i g u r e 19 P a r t i a l i H NMR S p e c t r a o f t h e P h o t o l y s a t e o f C o m p o u n d 96 ( I n i t i a l l y 10 m g , 0 . 0 3 m m o l e s ) i n t h e S o l i d S t a t e . B o t t o m : w i t h o u t E u ( h f c ) 3 . M i d d l e : w i t h 3 x 1 0 " ^ m m o l e s a d d i t i o n o f E u ( h f c ) 3 . T o p : w i t h 6 x 1 0 " ^ m m o l e s a d d i t i o n o f E u ( h f c ) 3 . 1 2 3 -T h e s t r i k i n g f e a t u r e o b s e r v e d i n t h e p h o t o l y s i s o f t h e c h i r a l c r y s t a l s o f 96 a s s e e n i n T a b l e 10 i s t h a t p h o t o p r o d u c t 152 i s f o r m e d i n h i g h e n a n t i o m e r i c e x c e s s , w h e r e a s i t s r e g i o i s o m e r 153 i s p r o d u c e d a s a r a c e m i c m i x t u r e ( w i t h i n t h e l i m i t s o f t h e m e t h o d , a p p r o x i m a t e l y ± 3% a c c u r a c y ^ 4 ) . T o d a t e , a l l r e p o r t e d a b s o l u t e a s y m m e t r i c s y n t h e s e s ( o f w h i c h t h e r e a r e v e r y f e w ) h a v e b e e n c o n c e r n e d w i t h a s i n g l e p a t h w a y v a r i e t y ; t h a t i s , o n l y o n e p r o d u c t i s f o r m e d w i t h h i g h e n a n t i o m e r i c e x c e s s i n m o s t c a s e s . T h e p r e s e n t s t u d y p r o v i d e s t h e f i r s t d e m o n s t r a t i o n t h a t p h o t o r e a c t i o n o f a c h i r a l c r y s t a l h a v i n g d u a l p a t h w a y s c a n l e a d t o p r o d u c t s o f w i d e l y d i f f e r i n g o p t i c a l a c t i v i t y . I t c a n a l s o b e n o t e d f r o m T a b l e 10 t h a t h i g h e r o p t i c a l y i e l d s f o r c o m p o u n d 152 a r e a c h i e v e d b y c o n d u c t i n g t h e p h o t o l y s i s o f t h e c h i r a l c r y s t a l s a t l o w e r t e m p e r a t u r e s , s u c h a s a t - 2 0 ° C . R a i s i n g t h e t e m p e r a t u r e c a u s e s a n o t i c e a b l e d i m i n u t i o n o f t h e e n a n t i o s e l e c t i v i t y . I n c o n t r a s t , c h a n g i n g t h e r e a c t i o n t e m p e r a t u r e h a s n o e f f e c t o n t h e e n a n t i o s e l e c t i v i t y f o r t h e f o r m a t i o n o f p r o d u c t 153 i n t h e s o l i d s t a t e . I t s h o u l d b e p o i n t e d o u t t h a t t h e o b s e r v e d t e m p e r a t u r e e f f e c t o n t h e e n a n t i o s e l e c t i v i t y o f t h e f o r m a t i o n o f 152 i s n o t c a u s e d b y t h e c r y s t a l m e l t i n g o f t h e s a m p l e , w h i c h may r e s u l t i n t h e l o s s o f t o p o c h e m i c a l c o n t r o l o v e r t h e p h o t o t r a n s f o r m a t i o n . C r y s t a l m e l t i n g w a s n o t o b s e r v e d u n d e r t h e m i c r o s c o p e i n a n y o f t h e r u n s , e v e n i n t h e c a s e o f i r r a d i a t i o n a t t h e r a i s e d t e m p e r a t u r e ( 3 8 ° C ) . U n d e r t h e c o n d i t i o n s o f r o o m o r h i g h e r t e m p e r a t u r e s , h o w e v e r , t h e s t a r t i n g s i n g l e c r y s t a l was f o u n d t o f a l l a p a r t t o p o w d e r y c r y s t a l l i n e s o l i d a f t e r t h e i r r a d i a t i o n was c o m p l e t e d . T h i s i s p e r h a p s d u e t o t h a t a c c u m u l a t i o n o f t h e p h o t o p r o d u c t s i n t h e c r y s t a l may r e s u l t i n d i s r u p t i o n o f t h e b u l k c r y s t a l l a t t i c e . I f t h e 124 p r o d u c t s a r e i n c a p a b l e o f f o r m i n g a s o l i d s o l u t i o n w i t h t h e r e a c t a n t i n t h e c r y s t a l l a t t i c e o r v i c e v e r s a , r e o r g a n i z a t i o n b e t w e e n p r o d u c t s a n d t h e r e a c t i n g m o l e c u l e s i n t h e s o l i d may b e r e f l e c t e d b y c r y s t a l b r e a k i n g . S u c h c r y s t a l b r e a k i n g d u r i n g t h e p h o t o l y s i s o f 96 w a s a l s o e v i d e n t a t l o w t e m p e r a t u r e s , b u t w a s m u c h l e s s s e v e r e c o m p a r e d t o t h e r o o m t e m p e r a t u r e i r r a d i a t i o n . I t s e e m s p o s s i b l e t h a t , o w i n g t o t h e d i s r u p t i o n o f t h e c r y s t a l l a t t i c e , p a r t i a l l o s s o f t o p o c h e m i c a l c o n t r o l c o u l d r e s u l t ; t h i s m i g h t e x p l a i n t h e c h a n g e s i n e n a n t i o s e l e c t i v i t y w i t h t e m p e r a t u r e . R e g a r d i n g t h e w i d e l y d i f f e r e n t e n a n t i o s e l e c t i v i t i e s o b s e r v e d i n t h e f o r m a t i o n o f t h e p h o t o p r o d u c t s 152 ( c a . 60% e . e . a t r o o m t e m p e r a t u r e ) a n d 153 ( r a c e m i c ) , we s u g g e s t t h a t t h e n a t u r e o f t h e c r y s t a l s t r u c t u r e d e t e r m i n e s o v e r a l l r e g i o - a n d e n a n t i o s e l e c t i v i t y , a n d t h a t t h e e n a n t i o s e l e c t i v i t y n e e d n o t b e h i g h i n s o l i d s t a t e a s y m m e t r i c s y n t h e s e s . A n o t h e r i n t e r e s t i n g p o i n t t h a t d e s e r v e s m e n t i o n i s t h e " s p o n t a n e o u s r e s o l u t i o n " o f a c h i r a l o r g a n i c m o l e c u l e s i n t o e n a n t i o m o r p h o u s a n t i p o d e s . U n d e r t h e p r e s e n t e x p e r i m e n t a l c o n d i t i o n s , b o t h e n a n t i o m o r p h o u s f o r m s o f t h e c h i r a i c r y s t a l s o f 96, i . e . , t h e l e f t -a n d t h e r i g h t - h a n d e d , a r e o b t a i n e d f r o m t h e c r y s t a l l i z a t i o n . T h i s i s r e f l e c t e d b y t h e s i g n o f o p t i c a l r o t a t i o n o f t h e o p t i c a l l y a c t i v e p h o t o p r o d u c t 152 ( T a b l e 1 0 ) . I n some o f t h e r u n s , t h e o p t i c a l l y a c t i v e p r o d u c t 152 s h o w s a p o s i t i v e r o t a t i o n , w h i l e o t h e r s a r e n e g a t i v e . I t i s u n d e r s t o o d t h a t t h e n u c l e a t i o n o f a c h i r a l m o l e c u l e s t o f o r m a n o p t i c a l l y a c t i v e c h i r a i c r y s t a l i s a p r o c e s s o f s y m m e t r y b r e a k i n g a t a m i c r o s c o p i c l e v e l , b u t t h e s y m m e t r y i s r e s t o r e d i n t h e c r y s t a l l i z a t i o n i n t h a t s t a t i s t i c a l l y e q u a l a m o u n t s o f l e v o ( l ) - a n d d e x t r o ( d ) - c r y s t a l s w i l l b e o b t a i n e d . E x p e r i m e n t s o n t h e c r y s t a l l i z a t i o n o f 1 , 1 ' - b i n a p h t h y l b y 125 P i n c o c k e t a l . ' c l e a r l y s h o w e d t h a t t h e two e n a n t i o m o r p h s w e r e f o u n d i n e q u a l p r o p o r t i o n s . H o w e v e r , e n a n t i o s e l e c t i v e c r y s t a l l i z a t i o n c a n b e 87 o b t a i n e d b y a p p r o p r i a t e i n t e r v e n t i o n s u c h a s s e e d i n g . T h a t i s , c r y s t a l s w i t h t h e same h a n d n e s s c a n b e f o r m e d i n e x c e s s o v e r t h e o t h e r o n e b y s e e d i n g t h e s o l u t i o n w i t h o n e a n t i p o l e d . T h e s e e d i n g m e t h o d w a s u s e d i n t h e c r y s t a l l i z a t i o n o f t h e l a c t o n e - e s t e r 96 i n t h e p r e s e n t s t u d y f o r t h e p u r p o s e o f o b t a i n i n g l a r g e c h i r a l s i n g l e c r y s t a l s . H o w e v e r , t h e o p t i c a l p u r i t y o f t h e r e s u l t i n g c h i r a l c r y s t a l s f r o m t h e c r y s t a l l i z a t i o n 8 8 w a s n o t d e t e r m i n e d . I n t e r e s t i n g l y , K o n d e p u d i a n d c o - w o r k e r s h a v e d e m o n s t r a t e d i n a v e r y r e c e n t r e p o r t t h a t , u n d e r w e l l c o n t r o l l e d c r y s t a l l i z i n g c o n d i t i o n s , o p t i c a l l y p u r e ( 9 9 . 7 % ) c r y s t a l s o f a n i n o r g a n i c s a l t ( N a C 1 0 3 ) c o u l d b e f o r m e d b y a n a s y m m e t r i c c r y s t a l l i z a t i o n p r o c e s s f r o m a c h i r a l , s p e c i e s . 4 . M e c h a n i s t i c I n t e r p r e t a t i o n o f t h e S o l i d S t a t e A s y m m e t r i c I n d u c t i o n f r o m L a c t o n e - E s t e r 96 T h e q u e s t i o n we a s k e d o u r s e l v e s i s w h y t h e i n f l u e n c e o f t h e c r y s t a l l a t t i c e e x e r t s d i f f e r e n t e f f e c t s o n t h e a s y m m e t r i c i n d u c t i o n i n t h e d u a l p a t h w a y s o f c o m p o u n d 9 6 . T o h e l p t o u n d e r s t a n d t h e s t r u c t u r e -r e a c t i v i t y r e l a t i o n s h i p s i n s u c h a p h o t o t r a n s f o r m a t i o n , t h e m o l e c u l a r c r y s t a l s t r u c t u r e was e x a m i n e d a g a i n . We s u g g e s t t h a t t h e d i f f e r e n c e may s t e m f r o m a n i n t e r m o l e c u l a r s t e r i c e f f e c t i n t h e c r y s t a l t h a t f a v o r s p a t h a - x o v e r p a t h a - x ' ( F i g u r e 1 6 ) . S u c h i n t e r m o l e c u l a r s t e r i c e f f e c t s i n u n i m o l e c u l a r p r o c e s s e s a r e u n i q u e t o s o l i d s t a t e r e a c t i o n s . M o l e c u l a r m o d e l s s h o w t h a t a s b o n d s a - x a n d a - x ' b e g i n t o f o r m , t h e COOCH3 g r o u p a t p o s i t i o n a s w i n g s t h r o u g h a w i d e a r c e i t h e r t o w a r d ( a - x ) o r a w a y ( a -126 -x ' ) f r o m t h e v i e w e r ( F i g u r e 1 6 ) . H o w e v e r , t h e two p a t h w a y s a r e d i f f e r e n t i a t e d b y t h e s p e c i f i c s p a t i a l a r r a n g e m e n t o f t h e n e i g h b o r i n g r e a c t a n t s . T h e c r y s t a l p a c k i n g d i a g r a m ( F i g u r e 2 0 ) c l e a r l y s h o w s t h a t t h e l a t t e r p a t h w a y ( b u t n o t t h e f o r m e r ) i s h i n d e r e d b y a h y d r o g e n a t o m f r o m a n e i g h b o r i n g m o l e c u l e t h a t l i e s 2 . 4 9 A d i r e c t l y b e h i n d t h e e t h e r o x y g e n a t o m o f t h e e s t e r g r o u p . T h i s i s s u b s t a n t i a l l y l e s s t h a n 2 . 7 2 A, 82 t h e s u m o f t h e v a n d e r W a a l s r a d i i f o r o x y g e n a n d h y d r o g e n . T h e r e f o r e , a - x ' b o n d i n g w i l l b e o p p o s e d b y s u c h s t e r i c h i n d r a n c e . I n c o n t r a s t , i t i s a p p a r e n t t h a t b o t h s i d e s o f t h e l a c t o n e r i n g a r e t i g h t l y p a c k e d , a n d t h i s may a c c o u n t f o r t h e l a c k o f e n a n t i o s e l e c t i v i t y i n t h e f o r m a t i o n o f t h e p h o t o p r o d u c t 153 a s w e l l a s t h e d i m i n u t i o n i n t h e r e l a t i v e a m o u n t o f t h i s p r o d u c t f o r m e d i n t h e s o l i d s t a t e ( 1 5 2 : 1 5 3 = 1 3 : 8 7 ) c o m p a r e d t o s o l u t i o n ( 1 5 2 : 1 5 3 = 0 : 1 0 0 ) . S i m i l a r s t e r i c e f f e c t s h a v e b e e n s u g g e s t e d t o b e r e s p o n s i b l e f o r d e t e r m i n i n g t h e r e g i o s e l e c t i v i t i e s o f d i - 7 r - m e t h a n e p h o t o r e a c t i o n s i n t h e s o l i d s t a t e . ^ A l t h o u g h s u c h m e c h a n i s t i c s p e c u l a t i o n s s e e m p l a u s i b l e , f i n a l c o n f i r m a t i o n o f t h e s t r u c t u r e -r e a c t i v i t y c o r r e l a t i o n s m u s t w a i t u n t i l t h e a b s o l u t e c o n f i g u r a t i o n s o f b o t h t h e s t a r t i n g m a t e r i a l 96 a n d o p t i c a l l y a c t i v e p r o d u c t 153 a r e d e t e r m i n e d . - 127 F i g u r e 20 C r y s t a l P a c k i n g D i a g r a m o f L a c t o n e - E s t e r 96 . B. P h o t o c h e m i s t r y o f M e t h y l L a c t o n e - E s t e r 97 T o e x t e n d t h e s t u d i e s o n t h e l a c t o n e - e s t e r 96 w h i c h s h o w e d n o v e l r e g i o s e l e c t i v i t y i n t h e d i - r c - m e t h a n e r e a c t i o n a n d t o f u r t h e r s u p p o r t t h e i d e a t h a t i n t r a m o l e c u l a r H - - - H s t e r i c i n t e r a c t i o n s d i r e c t t h e r e g i o s e l e c t i v i t y , c o m p o u n d 97 , w h i c h h a s a m e t h y l g r o u p o n t h e l a c t o n e r i n g , was s y n t h e s i z e d . S i n c e i t i s c l e a r t h a t t h e m e t h y l g r o u p i s b u l k i e r t h a n t h e h y d r o g e n a t o m , o n e may e x p e c t t h a t i n t r o d u c t i o n t h e m e t h y l g r o u p w i l l c r e a t e m u c h m o r e s t e r i c h i n d r a n c e o n o n e s i d e o f t h e l a c t o n e r i n g ( C H 3 - - - H i n t e r a c t i o n ) t h a n t h e o t h e r ( H - • - H i n t e r a c t i o n ) . B a s e d o n o u r p r e v i o u s i n t e r p r e t a t i o n o f t h e p h o t o c h e m i s t r y o f t h e l a c t o n e - e s t e r 96, t h e i n i t i a l b e n z o - v i n y l b r i d g i n g i n t h e c a s e o f t h e m e t h y l l a c t o n e - e s t e r 97 s h o u l d o c c u r f a v o r a b l y t h r o u g h p a t h w a y B ( I ) b y r e l e a s i n g t h e m o r e s e v e r e C H 3 - - - H s t e r i c h i n d r a n c e u p o n i r r a d i a t i o n 128 -( S c h e m e 5 3 ) . I n o t h e r w o r d s , we w o u l d e x p e c t t h a t t h e d i - n - m e t h a n e p h o t o r e a r r a n g e m e n t o f t h e m e t h y l l a c t o n e - e s t e r 97 o c c u r s p r e f e r e n t i a l l y a t t h e m o r e s t e r i c a l l y h i n d e r e d s i d e . 1. P h o t o l y s i s o f Meth y l L a c t o n e - E s t e r 97 i n S o l u t i o n D i r e c t o r a c e t o n e - s e n s i t i z e d i r r a d i a t i o n o f t h e m e t h y l l a c t o n e -e s t e r 97 i n s o l u t i o n p h a s e w a s s h o w n t o g i v e two p h o t o p r o d u c t s b y GC a n d •*"H NMR i n a r a t i o o f 7 7 : 2 3 . I s o l a t i o n o f e a c h p h o t o p r o d u c t was a c c o m p l i s h e d b y a p r e p a r a t i v e p h o t o l y s i s i n a c e t o n e a n d s u b s e q u e n t p u r i f i c a t i o n t h r o u g h c o l u m n c h r o m a t o g r a p h y . T h e two p r o d u c t s w e r e i d e n t i f i e d a s t h e i s o m e r i c p h o t o p r o d u c t s 168 (77%) a n d 170 (23%) ( S c h e m e 5 3 ) . 170 S c h e m e 53 P h o t o t r a n s f o r m a t i o n o f M e t h y l L a c t o n e - E s t e r 97 i n S o l u t i o n . 129 T h e s t r u c t u r e s o f c o m p o u n d s 168 a n d 1 7 0 w e r e e s t a b l i s h e d b y s p e c t r o s c o p i c a n a l y s e s , p a r t i c u l a r l y b y c o m p a r i s o n o f t h e i r •'"H NMR s p e c t r a w i t h t h a t o f c o m p o u n d 153 f r o m t h e s o l u t i o n p h o t o l y s i s o f t h e l a c t o n e - e s t e r 9 6 , w h i c h p r o v e d t o b e q u i t e s i m i l a r . I n r e g a r d t o t h e s t e r e o c h e m i s t r y o f t h e two s t r u c t u r e s , NOE d i f f e r e n c e e x p e r i m e n t s w e r e f o u n d t o b e v e r y u s e f u l i n d i f f e r e n t i a t i n g t h e two e p i m e r s . M o l e c u l a r m o d e l s s h o w t h a t t h e l a c t o n e m e t h y l g r o u p i n t h e m a j o r p h o t o p r o d u c t 168 i s m u c h c l o s e r t o t h e a d j a c e n t a r o m a t i c h y d r o g e n a t o m t h a n i s t h e l a c t o n e m e t h i n e h y d r o g e n a t o m . O n t h e o t h e r h a n d , t h e s i t u a t i o n i s r e v e r s e d f o r t h e i s o m e r 1 7 0 . A n N O E d i f f e r e n c e m e a s u r e m e n t o n c o m p o u n d 168 ( F i g u r e 21 ) s h o w s t h a t i r r a d i a t i o n o f t h e l a c t o n e m e t h y l d o u b l e t l e a d s t o a s i g n a l e n h a n c e m e n t o f t h e a d j a c e n t a r o m a t i c h y d r o g e n a t o m , b u t s a t u r a t i o n o f t h e l a c t o n e m e t h i n e p r o t o n a t 8 = 5 . 3 0 ppm d o e s n o t . T h e s e r e s u l t s s u p p o r t t h e s t r u c t u r a l a s s i g n m e n t o f c o m p o u n d 1 6 8 . I n a s i m i l a r f a s h i o n , t h e s t r u c t u r e o f t h e e p i m e r 1 7 0 i s s u p p o r t e d b y NOE d i f f e r e n c e m e a s u r e m e n t s ( F i g u r e 2 2 ) . I r r a d i a t i o n o f t h e l a c t o n e m e t h i n e p r o t o n (CHCH3) r e s u l t s i n a s i g n a l e n h a n c e m e n t o f t h e a d j a c e n t a r o m a t i c p r o t o n , w h e r e a s n o s u c h e n h a n c e m e n t i s o b s e r v e d i f t h e c o r r e s p o n d i n g m e t h y l h y d r o g e n a t o m s (CHCH3) a r e i r r a d i a t e d . T h e a s s i g n m e n t o f t h e s t e r e o c h e m i s t r y o f t h e two e p i m e r s was a l s o s u p p o r t e d b y t h e c h e m i c a l s h i f t s o f t h e CHCH3 f r a g m e n t i n t h e i r "^H NMR s p e c t r a . A s s h o w n b y t h e m o l e c u l a r m o d e l o f c o m p o u n d 1 6 8 , t h e c o n c e r n e d m e t h y l g r o u p (CHCH3) i s f o u n d i n t h e d e s h i e l d i n g r e g i o n o f t h e a r o m a t i c r i n g . T h i s i s s u p p o r t e d b y t h e r e s o n a n c e o f t h i s m e t h y l g r o u p a t 5 = 2 . 0 5 ppm c o m p a r e d t o 5 = 1 . 5 5 ppm f o r t h e c o r r e s p o n d i n g m e t h y l g r o u p i n c o m p o u n d 1 7 0 . I n c o n t r a s t , t h e m e t h i n e p r o t o n (CHCH3) i n t h e c a s e o f 130 -p h o t o p r o d u c t 168 i s s i t u a t e d i n t h e d e s h i e l d i n g r e g i o n o f t h e a r o m a t i c r i n g a n d t h e r e f o r e i t r e s o n a t e s d o w n f i e l d (6 = 5 . 5 5 p p m ) c o m p a r e d t o t h a t o f t h e m e t h i n e p r o t o n o f i s o m e r 170 (6* «• 5 . 3 0 p p m ) . , _ _ _ ! , f 7 . 0 6 . 0 5 . 0 4 . 0 3 . 0 PPM 2 . 0 F i g u r e 21 P a r t i a l NMR S p e c t r a o f P h o t o p r o d u c t 1 6 8 . B o t t o m : r o u t i n e s p e c t r u m . T o p a n d m i d d l e : NOE d i f f e r e n c e a f t e r i r r a d i a t i o n . - 131 -ure 22 P a r t i a l -""H NMR Spectra of Photoproduct 170. Bottom: routine spectrum. Top and middle: NOE difference a f t e r i r r a d i a t i o n . 132 T u r n i n g now t o a d i s c u s s i o n o f t h e s o l u t i o n p h a s e r e s u l t s , we n o t e f i r s t o f a l l t h a t t h e r e g i o s e l e c t i v i t y i s s i m i l a r t o t h a t o b t a i n e d i n t h e c a s e o f l a c t o n e e s t e r 9 6 . T h a t i s , t h e r e a r r a n g e m e n t p r o c e e d s e x c l u s i v e l y via t h e p a t h B m e c h a n i s m i n s o l u t i o n . T h i s o b s e r v a t i o n i s i n a g r e e m e n t w i t h t h e p r e v i o u s s u g g e s t i o n i n t h e c a s e o f c o m p o u n d 96 t h a t i n i t i a l b e n z o - v i n y l b r i d g i n g i s p r e f e r r e d via p a t h w a y B b y r e l e a s i n g t h e i n t r a m o l e c u l a r s t e r i c s t r a i n . S e c o n d l y , s t r o n g s u p p o r t f o r t h e p r o p o s e d s t e r i c e f f e c t o n t h e r e g i o s e l e c t i v i t y o f t h e p h o t o r e a r r a n g e m e n t o f d i b e n z o b a r r e l e n e l a c t o n e s c o m e s f r o m t h e o b s e r v a t i o n t h a t t h e p r e d o m i n a n t p h o t o p r o d u c t i n t h e s o l u t i o n p h a s e p h o t o l y s i s o f t h e m e t h y l l a c t o n e - e s t e r 97 i s t h e s t e r e o i s o m e r 1 6 8 , w h i c h i s d e r i v e d f r o m i n i t i a l b o n d i n g a t t h e m o r e s t e r i c a l l y h i n d e r e d s i d e ( p a t h B ( I ) i n S c h e m e 5 3 ) . I t s e e m s r e a s o n a b l e t h a t r e l e a s e o f t h e m o r e s e v e r e s t e r i c i n t e r a c t i o n s b e t w e e n t h e m e t h y l g r o u p a n d t h e a d j a c e n t a r o m a t i c h y d r o g e n a t o m b y b o n d f o r m a t i o n i s p r e f e r r e d o v e r r e l e a s e o f t h e H - • - H s t e r i c i n t e r a c t i o n s . 2 . S o l i d S t a t e R e s u l t s I n a f a s h i o n s i m i l a r t o t h e s o l i d s t a t e p h o t o l y s i s o f t h e l a c t o n e -e s t e r 9 6 , i t was e x p e c t e d t h a t , i n p r i n c i p l e , i r r a d i a t i o n o f t h e m e t h y l l a c t o n e - e s t e r 97 i n t h e c r y s t a l l i n e p h a s e w o u l d p r o c e e d via b o t h p a t h w a y s A a n d B l e a d i n g t o two d i f f e r e n t r e g i o i s o m e r s . I t i s a p p a r e n t , h o w e v e r , t h a t e a c h p a t h w a y ( p a t h A o r p a t h B ) i s c a p a b l e o f p r o d u c i n g a p a i r o f d i a s t e r e o m e r s , s i n c e t h e r e a r e two d i f f e r e n t i n i t i a l b r i d g i n g s i n e a c h o f t h e p a t h w a y s . T h e r e f o r e , f o u r p h o t o p r o d u c t s c o u l d b e p o s s i b l e u p o n p h o t o l y s i s o f c o m p o u n d 97 i n t h e s o l i d s t a t e ( S c h e m e 5 4 ) . P r o d u c t s 133 168 a n d 170 a r e d e r i v e d f r o m p a t h w a y B a s d i s c u s s e d i n t h e p r e v i o u s s e c t i o n ; r e g i o i s o m e r s 1 7 1 a n d 1 7 2 , w h i c h a r e n o t o b s e r v e d i n t h e s o l u t i o n p h a s e i r r a d i a t i o n , a r e d e r i v e d via p a t h w a y A ( S c h e m e 5 4 ) . 171 172 S c h e m e 54 P h o t o r e a r r a n g e m e n t o f M e t h y l L a c t o n e - E s t e r 97 i n t h e S o l i d S t a t e . I n f a c t , i r r a d i a t i o n o f s i n g l e c r y s t a l s o f 97 was f o u n d t o p r o d u c e o n l y t h r e e p h o t o p r o d u c t s . Two o f t h e m w e r e i d e n t i f i e d a s c o m p o u n d s 168 a n d 1 7 0 ; t h e t h i r d p r o d u c t p r o v e d t o b e t h e i s o m e r 1 7 1 . T h e p r o d u c t r a t i o w a s d e t e r m i n e d t o b e 1 6 8 : 1 7 0 : 1 7 1 = 6 8 : 2 2 : 1 0 i n t h e s o l i d s t a t e , a n d t h e r a t i o was f o u n d t o r e m a i n c o n s t a n t a t v a r i o u s c o n v e r s i o n s o f t h e s t a r t i n g m a t e r i a l . H o w e v e r , t h e o t h e r i s o m e r 172 c o u l d n o t b e d e t e c t e d b y GC a n d 1 H NMR. - 134 -T h e s t r u c t u r e o f t h e s o l i d s t a t e p h o t o p r o d u c t 1 7 1 w a s e s t a b l i s h e d b y F T I R , M S , C a n d H NMR s p e c t r o s c o p y , p a r t i c u l a r l y b a s e d o n t h e s p e c t r a l s i m i l a r i t y b e t w e e n t h e ''"H NMR o f c o m p o u n d 1 7 1 a n d i t s a n a l o g u e 1 5 2 . H o w e v e r , t h e p r o d u c t 171 c o u l d n o t b e d i s t i n g u i s h e d f r o m i t s e p i m e r 172 b a s e d o n t h e s p e c t r o s c o p i c a n a l y s i s . T h e d e f i n i t i v e e v i d e n c e t h a t c o n f i r m s t h e s t r u c t u r a l a s s i g n m e n t o f 1 7 1 o r i g i n a t e s f r o m t h e f o l l o w i n g i n d e p e n d e n t s y n t h e s i s o f t h e two c o m p o u n d s , 1 7 1 a n d 1 7 2 , a n d t h e s u b s e q u e n t d e t e r m i n a t i o n o f t h e c r y s t a l s t r u c t u r e o f 1 7 1 . S c h e m e 55 s h o w s t h e p r e p a r a t i o n o f c o m p o u n d s 171 a n d 1 7 2 . I t i n v o l v e s a G r i g n a r d r e a c t i o n o f d i b e n z o s e m i b u l l v a l e n e a l d e h y d e 118 w h i c h 52 w a s p r e p a r e d a c c o r d i n g t o t h e k n o w n p r o c e d u r e . I n t h i s s t e p , two c o r r e s p o n d i n g d i a s t e r e o m e r i c a l c o h o l d e r i v a t i v e s w e r e f o r m e d b y t h e a d d i t i o n o f m e t h y l m a g n e s i u m b r o m i d e ( C ^ M g B r ) t o t h e m o r e r e a c t i v e a l d e h y d e c a r b o n y l g r o u p . T h e s e two d i a s t e r e o m e r s , 173 a n d 1 7 4 , w e r e t h e n s e p a r a t e d a t t h i s s t a g e . A c i d - c a t a l y z e d l a c t o n i z a t i o n o f e a c h o f t h e a l c o h o l d e r i v a t i v e s 173 a n d 1 7 4 r e s u l t e d i n t h e f o r m a t i o n o f t h e c o r r e s p o n d i n g d i b e n z o s e m i b u l l v a l e n e l a c t o n e s 1 7 1 a n d 172 r e s p e c t i v e l y . T h e s t r u c t u r e s o f c o m p o u n d s 1 7 3 a n d 174 w e r e a s s i g n e d a c c o r d i n g l y b a s e d o n t h i s t r a n s f o r m a t i o n . A n X - r a y c r y s t a l l o g r a p h i c a n a l y s i s o f c o m p o u n d 1 7 1 p r o v e d t h e s t r u c t u r a l a s s i g n m e n t . A s t e r e o d i a g r a m o f t h e m o l e c u l e 1 7 1 i s g i v e n i n F i g u r e 2 3 . F r o m t h i s , t h e s t r u c t u r e o f t h e i s o m e r 172 i s r e a s o n a b l y a s s u m e d b a s e d o n i t s s p e c t r o s c o p i c d a t a , w h i c h a r e s i m i l a r t o t h o s e o f 1 7 1 . - 135 -S c h e m e 55 I n d e p e n d e n t S y n t h e s e s o f P h o t o p r o d u c t 1 7 1 a n d I t s I s o m e r 1 7 2 . F i g u r e 23 S t e r e o d i a g r a m o f t h e M o l e c u l e 1 7 1 . 136 R e g a r d i n g t h e r e g i o s e l e c t i v i t y i n t h e s o l i d s t a t e r e a c t i o n o f t h e m e t h y l l a c t o n e - e s t e r 9 7 , i t i s f o u n d t h a t p r o d u c t s 168 a n d 1 7 0 , w h i c h o r i g i n a t e f r o m r e a c t i o n p a t h w a y B , a r e p r e d o m i n a n t i n t h e s o l i d s t a t e . T h e p h o t o p r o d u c t 1 7 1 v i a p a t h A a c c o u n t s f o r o n l y 10% o f t h e t o t a l y i e l d . T h e p r o d u c t d i s t r i b u t i o n s i n s o l u t i o n a n d i n t h e s o l i d s t a t e f o r b o t h l a c t o n e s , 96 a n d 9 7 , a r e s u m m a r i z e d i n T a b l e 11 f o r c o n v e n i e n c e o f c o m p a r i s o n b e t w e e n t h e two p h o t o t r a n s f o r m a t i o n s . T a b l e 11 P r o d u c t D i s t r i b u t i o n s i n t h e S o l u t i o n a n d t h e S o l i d S t a t e I r r a d i a t i o n s o f L a c t o n e s 96 a n d 9 7 . a C o m p o u n d M e d i u m P r o d u c t v i a P a t h A (%) P r o d u c t v i a P a t h B (%) L a c t o n e 96 S o l u t i o n 152 ( 0 ) 1 5 3 ( 1 0 0 ) L a c t o n e 96 C r y s t a l 152 ( 1 3 ) 153 ( 8 7 ) L a c t o n e 97 S o l u t i o n 1 7 1 ( 0 ) + 172 ( 0 ) 168 ( 7 7 ) + 1 7 0 ( 2 3 ) L a c t o n e 97 C r y s t a l 1 7 1 ( 1 0 ) + 172 (0 ) 168 ( 6 8 ) + 1 7 0 ( 2 2 ) a A n a l y s i s b y GC a n d i H NMR. B y c o m p a r i s o n , i t c a n b e s e e n f r o m T a b l e 11 t h a t b o t h c o m p o u n d s b e h a v e q u i t e s i m i l a r l y i n t h e d i - ? r - m e t h a n e p h o t o r e a r r a n g e m e n t . U p o n i r r a d i a t i o n i n s o l u t i o n , t h e y b o t h p r o c e e d t h r o u g h p a t h w a y B e x c l u s i v e l y t o g i v e c o r r e s p o n d i n g d i b e n z o s e m i b u l l v a l e n e p r o d u c t s . O n t h e o t h e r h a n d , b o t h p a t h A a n d p a t h B p h o t o p r o d u c t s a r e f o r m e d i n s o l i d s t a t e i r r a d i a t i o n s , b u t p a t h w a y B i s p r e d o m i n a n t i n b o t h c a s e s . - 137 -We n o t e t h a t a n i n t e r e s t i n g f e a t u r e i n t h e s o l i d s t a t e r e a c t i o n o f t h e m e t h y l l a c t o n e - e s t e r 97 i s t h e s t e r e o s e l e c t i v i t i e s i n t h e p a t h w a y s A a n d B . I t c a n b e s e e n f r o m T a b l e 11 t h a t t h e p r o d u c t r a t i o o f 1 6 8 : 1 7 0 , w h i c h r e p r e s e n t s s t e r e o s e l e c t i v i t y i n p a t h B , i s n e a r l y u n c h a n g e d b y c h a n g i n g t h e r e a c t i o n m e d i u m f r o m s o l u t i o n p h a s e ( 7 7 : 2 3 ) t o t h e c r y s t a l l i n e p h a s e ( 6 8 : 2 2 ) . I n c o n t r a s t , t h e r e i s c o m p l e t e d i s c r i m i n a t i o n f o r t h e f o r m a t i o n o f p h o t o p r o d u c t 1 7 1 v i a p a t h w a y A i n t h e s o l i d s t a t e p h o t o l y s i s . We s u g g e s t t h a t s u c h r e a c t i o n s t e r e o s e l e c t i v i t y m i g h t s t e m f r o m a s p e c i f i c c r y s t a l l a t t i c e e f f e c t . A l t h o u g h a t t h e p r e s e n t t i m e t h e m o l e c u l a r c r y s t a l s t r u c t u r e o f 97 i s n o t a v a i l a b l e ( X - r a y c r y s t a l l o g r a p h i c a n a l y s i s w e r e c a r r i e d o u t , h o w e v e r , c r y s t a l s t r u c t u r e h a s n o t b e e n s o l v e d o w i n g t o d i s o r d e r o f t h e c r y s t a l ) , f u r t h e r s t r u c t u r e - r e a c t i v i t y c o r r e l a t i o n s c a n b e p o s s i b l e f r o m t h e c r y s t a l l o g r a p h i c s t u d i e s . C . E l e c t r o n i c v e r s u s S t e r i c E f f e c t i n t h e P h o t o r e a r r a n g e m e n t o f L a c t o n e 98 I n f u r t h e r e f f o r t s t o s t u d y s t e r i c e f f e c t s o n t h e r e g i o s e l e c t i v i t y o f t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f l a c t o n e - e s t e r s , t h e l a c t o n e 98 w i t h o u t t h e m e t h y l e s t e r g r o u p a t t h e 1 1 - v i n y l c a r b o n a t o m was s y n t h e s i z e d b y a n i n t r a m o l e c u l a r D i e l s - A l d e r c y c l o a d d i t i o n o f 9 -a n t h r y l m e t h y l p r o p y n o a t e ( S c h e m e 24 o n p a g e 4 5 ) . T h i s i s b a s e d o n t h e f o l l o w i n g c o n s i d e r a t i o n s . I n p r i n c i p l e , d i - w - m e t h a n e r e a c t i o n o f t h e l a c t o n e 98 may y i e l d two r e g i o i s o m e r i c p h o t o p r o d u c t s , 1 7 6 a n d 178 80 ( S c h e m e 56 ) . C i g a n e k h a s d e m o n s t r a t e d t h a t t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f c o m p o u n d s s i m i l a r t o 9 8 , i . e . 9 , 1 2 - b r i d g e d d i b e n z o b a r r e l e n e s 154 a n d 1 6 0 ( S c h e m e s 50 a n d 5 1 ) , g i v e two 138 r e g i o i s o m e r i c p h o t o p r o d u c t s u p o n i r r a d i a t i o n i n s o l u t i o n . I n t h e c a s e o f t h e l a c t o n e 9 8 , i n i t i a l b e n z o - v i n y l b r i d g i n g a t t h e b r i d g e h e a d u n s u b s t i t u t e d s i d e [ C ( l l ) - C ( 4 a ) ] l e a d i n g t o t h e r e g i o i s o m e r 1 7 6 i s e x p e c t e d t o b e p r e d o m i n a n t ( S c h e m e 5 6 ) , s i n c e t h e i n i t i a l l y f o r m e d b i r a d i c a l i n t e r m e d i a t e s p e c i e s 1 7 5 w i l l b e m o r e s t a b i l i z e d b y t h e c a r b o n y l g r o u p t h a n 1 7 7 . S u c h e l e c t r o n i c s t a b i l i z i n g e f f e c t s a r e 78 s u p p o r t e d b y t h e w o r k o f o t h e r s a n d a l s o b y t h e p r e s e n t s t u d i e s d i s c u s s e d i n a p r e v i o u s s e c t i o n o f t h i s t h e s i s ( S e c t i o n I V . A . ) . B y t h e s t e r i c a r g u m e n t d i s c u s s e d p r e v i o u s l y , h o w e v e r , t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f 98 w o u l d b e e x p e c t e d t o p r o c e e d via i n i t i a l b o n d i n g a t t h e b r i d g e h e a d s u b s t i t u t e d s i d e t o g i v e t h e r e g i o i s o m e r 1 7 8 , a s t h e s t e r i c i n t e r a c t i o n s b e t w e e n t h e m e t h y l e n e h y d r o g e n a t o m s a n d t h e a d j a c e n t a r o m a t i c h y d r o g e n a t o m s a r e p r e s e n t i n c o m p o u n d 9 8 . O u r i d e a s w e r e ( 1 ) t o f i n d w h i c h e f f e c t , s t e r i c o r e l e c t r o n i c , w o u l d b e t h e o v e r r i d i n g f a c t o r t h a t c o n t r o l s t h e r e a c t i o n r e g i o s e l e c t i v i t y a n d ( 2 ) t o s t u d y how t h e c r y s t a l l a t t i c e w o u l d a f f e c t t h e s e l e c t i v i t y . 1 7 6 o b s e r v e d 178 S c h e m e 56 D i - 7 r - M e t h a n e P h o t o r e a r r a n g e m e n t o f L a c t o n e 9 8 . 139 E x p e r i m e n t a l l y , t h e p h o t o r e a r r a n g e m e n t o f l a c t o n e 98 p r o c e e d e d t o a f f o r d o n l y p r o d u c t 176 u p o n i r r a d i a t i o n i n s o l u t i o n ( b o t h d i r e c t a n d a c e t o n e - s e n s i t i z e d ) a n d i n t h e s o l i d s t a t e a s w e l l ( S c h e m e 5 6 ) . T h e "^H 1 3 a n d C NMR, MS a n d F T I R s p e c t r a a r e i n c o m p l e t e a g r e e m e n t w i t h t h e a s s i g n m e n t o f s t r u c t u r e 1 7 6 . I n p a r t i c u l a r , t h i s p h o t o p r o d u c t i s c h a r a c t e r i z e d i n i t s "^H NMR s p e c t r u m b y a s h a r p s i n g l e t a t 6 — 3 . 9 7 ppm w h i c h c o r r e s p o n d s t o t h e two c y c l o p r o p y l p r o t o n s a s e x p e c t e d f o r t h e m i r r o r - s y m m e t r i c d i b e n z o s e m i b u l l v a l e n e s t r u c t u r e 1 7 6 . T h u s , t h e a b o v e r e s u l t s d e m o n s t r a t e t h a t t h e d i - 7 r - m e t h a n e r e a c t i o n o f t h e l a c t o n e 98 i s c o n t r o l l e d b y e l e c t r o n i c s t a b i l i z i n g e f f e c t s r a t h e r t h a n s t e r i c e f f e c t s . I n a d d i t i o n , t h e r e a c t i o n r e g i o s e l e c t i v i t y i s n o t c h a n g e d b y t h e c r y s t a l l a t t i c e . I n c o m p a r i s o n t o t h e p r e v i o u s s t u d i e s , i t s h o u l d b e n o t e d t h a t t h e p h o t o t r a n s f o r m a t i o n o f l a c t o n e 98 i s q u i t e s i m i l a r t o t h a t o f t h e 9 , 1 2 -u n b r i d g e d 9 , 1 0 - e t h e n o a n t h r a c e n e 100 ( S c h e m e 4 5 ) . T h e common f e a t u r e s i n t h e s e p h o t o t r a n s f o r m a t i o n s a r e ( 1 ) t h e p h o t o r e a r r a n g e m e n t p r o c e e d s i n a r e g i o s p e c i f i c m a n n e r via i n i t i a l b r i d g i n g a t t h e b r i d g e h e a d u n s u b s t i t u t e d s i d e ; t h e e x c i t e d t r i p l e t s t a t e o f 98 i s p e r h a p s i n v o l v e d , a s a c e t o n e - s e n s i t i z e d p h o t o l y s i s g i v e s t h e s a m e p r o d u c t a s d i r e c t i r r a d i a t i o n a n d (2 ) t h e s i n g l e t - d e r i v e d p h o t o p r o d u c t , i . e . , d i b e n z o c y c l o o c t a t e t r a e n e d e r i v a t i v e , i s n o t f o r m e d w i t h t h e d i r e c t i r r a d i a t i o n o f 98 a n d 1 0 0 , w h e r e a s o t h e r s i m i l a r c o m p o u n d s g i v e t h e d i b e n z o c y c l o o c t a t e t r a e n e s a s t h e m a j o r p h o t o p r o d u c t s w i t h t h e d i r e c t i r r a d i a t i o n . * ^ a ' ^ T h e r e a s o n f o r t h i s i s y e t u n c l e a r . 140 -D. Studies on the Photoreactivity of 9,10-Ethenoanthracene Lactones 96, 97, 98 and 93c In connection with the investigations of 9-substituted dibenzobarrelene compounds, we are i n t e r e s t e d i n studying the p h o t o r e a c t i v i t y possessed by t h i s type of compound i n terms of quantum y i e l d s ($) and reaction rate constants ( k r ) f o r the di-w-methane rearrangement. O r i g i n a l l y , i t was thought that the remarkable difference i n r e g i o s e l e c t i v i t y between the lactone-ester 96 and the 9-substituted dibenzobarrelene diester 93c might be due to the r e l a t i v e reaction rates i n pathways A and B. I t was thought that the rate of i n i t i a l bonding i n path B for the lactone-ester 96 might be increased by the s t e r i c H-•-H i n t e r a c t i o n s between the methylene and the adjacent aromatic hydrogen atoms compared to that i n compound 93c without such s t e r i c i n t e r a c t i o n s . Experimentally, i t was noted that lactone-ester 96 and methyl lactone-ester 97 displayed q u a l i t a t i v e l y much higher r e a c t i v i t y than the dibenzobarrelene diester 93c under s i m i l a r i r r a d i a t i o n conditions, both i n s o l u t i o n and c r y s t a l l i n e states. I n t e r e s t i n g l y , even room l i g h t could cause s i g n i f i c a n t photoreactions for the lactones 96 and 97 i n the two media. 1. Quantum Y i e l d ($) Measurements In the present studies, quantum y i e l d s ($) were measured i n 89 benzene at A •= 313 nm by using standard procedures (refer to Experimental section for d e t a i l s ) . Quantum y i e l d s ($) for the formation of the photoproducts from each of the s t a r t i n g materials were averaged over several measurements and are summarized i n Table 12. - 141 -T a b l e 12 Q u a n t u m Y i e l d s ( $ ) o f P r o d u c t F o r m a t i o n f r o m P h o t o l y s i s o f D i b e n z o b a r r e l e n e s 9 6 , 9 7 , 98 a n d 9 3 c . a S u b s t r a t e P h o t o p r o d u c t Q u a n t u m Y i e l d ( $ ) b T o t a l $ L a c t o n e - E s t e r 96 153 0 . 4 8 ± 0 . 0 7 0 . 4 8 ± 0 . 0 7 M e t h y l L a c t o n e - E s t e r 97 168 1 7 0 L a c t o n e 98 176 D i e s t e r 9 3 c 120 1 2 4 0 . 6 3 ± 0 . 0 5 0 . 1 5 ± 0 . 0 3 0 . 7 8 ± 0 . 0 5 0 . 0 2 0 ± 0 . 0 0 2 0 . 0 2 0 ± 0 . 0 0 2 0 . 0 8 9 ± 0 . 0 0 9 0 . 0 3 1 ± 0 . 0 0 4 0 . 1 2 ± 0 . 0 1 a b I r r a d i a t i o n a t 313 nm i n b e n z e n e a n d a n a l y s i s b y G C . Q u a n t u m y i e l d s w e r e d e t e r m i n e d a t t h e f o l l o w i n g c o n c e n t r a t i o n s : [ 9 6 ] = 0 . 0 1 M, [ 9 7 ] = 0 . 0 1 M, [ 9 3 c ] = 0 . 0 1 5 M a n d [ 9 8 ] - 0 . 0 1 M. I t c a n b e s e e n f r o m T a b l e 12 t h a t r e a r r a n g e m e n t o f t h e l a c t o n e -e s t e r 96 i s m u c h m o r e e f f i c i e n t ( $ — 0 . 4 8 ) t h a n t h a t o f t h e d i e s t e r 9 3 c (<£ = 0 . 1 2 ) . I t i s c l e a r t h a t s u c h a r e m a r k a b l e d i f f e r e n c e i n r e a c t i o n e f f i c i e n c y c o u l d o n l y b e a s c r i b e d t o t h e s t r u c t u r a l d i f f e r e n c e b e t w e e n t h e two c o m p o u n d s . T h i s s e e m s t o s u g g e s t t h a t t h e h i g h q u a n t u m y i e l d o b s e r v e d f o r c o m p o u n d 96 may l i e i n t h e i n t r a m o l e c u l a r s t e r i c i n t e r a c t i o n s p r e s e n t i n 9 6 , i f we a s s u m e t h a t c o m p o u n d s 96 a n d 9 3 c a r e 142 e l e c t r o n i c a l l y e q u i v a l e n t . F u r t h e r s u p p o r t f o r t h i s s p e c u l a t i o n i s f o u n d i n t h e q u a n t u m y i e l d m e a s u r e m e n t f o r t h e p r o d u c t f o r m a t i o n f r o m t h e m e t h y l l a c t o n e - e s t e r 9 7 . I n c r e a s i n g t h e s t e r i c h i n d r a n c e b y s u b s t i t u t i o n o f a m e t h y l g r o u p b u t w i t h o u t c h a n g i n g t h e e l e c t r o n i c s t r u c t u r e c a u s e s a n i n c r e a s e i n t h e q u a n t u m y i e l d t o $ = 0 . 7 8 . Q u a n t u m y i e l d s a n d t r i p l e t l i f e t i m e s f o r s o m e o t h e r d i b e n z o b a r r e l e n e c o m p o u n d s , w h i c h a r e t a k e n f r o m t h e l i t e r a t u r e , a r e l i s t e d i n T a b l e 1 3 . I t i s i n t e r e s t i n g t o c o m p a r e t h e s e q u a n t u m y i e l d s w i t h t h o s e d e t e r m i n e d i n t h e p r e s e n t w o r k ( T a b l e 1 2 ) . F i r s t , we n o t e t h a t t h e q u a n t u m y i e l d s f o r t h e l a c t o n e - e s t e r s 96 a n d 97 a r e s u b s t a n t i a l l y h i g h e r t h a n t h e r e s t o f c o m p o u n d s ( 2 . 5 - 4 0 f o l d h i g h e r d e p e n d i n g o n t h e c o m p o u n d ) . S e c o n d l y , i t c a n b e s e e n t h a t t h e q u a n t u m y i e l d s f o r t h e b r i d g e h e a d - s u b s t i t u t e d d i e s t e r 9 3 c a n d t h e l a c t o n e 98 ( T a b l e 1 2 ) a r e a p p r o x i m a t e l y i n t h e s a m e r a n g e a s t h o s e i n T a b l e 1 3 . I t s h o u l d b e p o i n t e d o u t t h a t t h e m e a s u r e d q u a n t u m y i e l d $ ( o v e r a l l r e a c t i o n e f f i c i e n c y ) i s d e t e r m i n e d b y t h e i n t e r s y s t e m c r o s s i n g q u a n t u m y i e l d ( $ i s c ) a n d t h e r e a c t i o n q u a n t u m y i e l d o f t h e e x c i t e d 90 91 t r i p l e t s t a t e ' a s f o u n d i n t h e e q u a t i o n ( 1 ) ( S c h e m e 5 7 ) . S p e c u l a t i o n o n t h e l a r g e d i f f e r e n c e b e t w e e n t h e t r i p l e t r e a c t i o n e f f i c i e n c i e s i s n o t p o s s i b l e w i t h o u t k n o w i n g t h e i n t e r s y s t e m c r o s s i n g q u a n t u m y i e l d ( $ ± s c ) o f e a c h o f t h e a b o v e c o m p o u n d s . I t i s c l e a r , a t l e a s t i n t h e c a s e o f c o m p o u n d 9 7 , t h a t t h e i n t e r s y s t e m c r o s s i n g p r o c e s s m u s t b e v e r y e f f i c i e n t , s i n c e t h e o v e r a l l r e a c t i o n q u a n t u m y i e l d ( $ ) o f 97 i s c l o s e 92 t o u n i t y . I n f a c t , i t h a s b e e n s u g g e s t e d t h a t p e r h a p s a v e r y e f f i c i e n t i n t e r s y s t e m c r o s s i n g w a s i n v o l v e d i n t h e d i - j r - m e t h a n e r e a r r a n g e m e n t o f some d i b e n z o b a r r e l e n e c o m p o u n d s , a s i t w a s f o u n d t h a t t h e s e c o m p o u n d s d o - 143 -not react from t h e i r excited s i n g l e t states to give the corresponding dibenzocyclooctatetraene products. In such cases, i t can be assumed that $ i s c = 1-Table i3 Quantum Yiel d s and T r i p l e t Lifetimes of Some 9,10-Ethenoanthracenes. Dibenzobarrelene Quantum Y i e l d ($) T r i p l e t Lifetime (ns) Ref. $ " $ i s c x *T (!) $ T = k r / (Sk d + k r) - k r x r ( 2 ) Scheme 57 Quantum Y i e l d and Reaction Rate Relationships. - 144 -F u r t h e r m o r e , i t s h o u l d b e p o i n t e d o u t t h a t t h e o v e r a l l r e a c t i o n e f f i c i e n c y i n t e r m s o f q u a n t u m y i e l d s ( $ ) d o e s n o t n e c e s s a r i l y r e p r e s e n t t h e r e l a t i v e r e a c t i o n r a t e s . I n o t h e r w o r d s , q u a n t u m y i e l d s may n o t b e u s e d a s r e l a t i v e m e a s u r e s o f t h e r e a c t i o n r a t e c o n s t a n t s . T h i s i s b e c a u s e , i n g e n e r a l , t h e q u a n t u m y i e l d ( $ ) f o r p r o d u c t f o r m a t i o n f r o m a t r i p l e t r e a c t i o n i s g o v e r n e d b y e q u a t i o n ( 2 ) i n S c h e m e 5 7 , w h e r e k r i s t h e r e a c t i o n r a t e c o n s t a n t f r o m t h e t r i p l e t , Sk^ i s t h e sum o f n o n -r e a c t i o n d e c a y r a t e c o n s t a n t s f r o m t h e t r i p l e t a n d r i s t h e l i f e t i m e o f t h e e x c i t e d t r i p l e t s t a t e . I n o r d e r t o s p e c u l a t e f u r t h e r o n t h e h i g h e r r e a c t i o n e f f i c i e n c i e s o b s e r v e d f o r t h e l a c t o n e - e s t e r s 96 ( $ = 0 . 4 8 ) a n d t h e m e t h y l l a c t o n e - e s t e r 97 ( $ = 0 . 7 8 ) c o m p a r e d t o t h e d i e s t e r 9 3 c ( $ = 0 . 1 2 ) , i t i s n e c e s s a r y t o o b t a i n t h e r e a c t i o n r a t e c o n s t a n t (kr) a n d t h e t r i p l e t l i f e t i m e s ( r ) f o r t h e s e c o m p o u n d s . s 2 . Q u e n c h i n g R e s u l t s o n t h e L a c t o n e - E s t e r 96 a n d D i e s t e r 9 7 . Q u e n c h i n g e x p e r i m e n t s w e r e c a r r i e d o u t t o d e t e r m i n e t h e t r i p l e t l i f e t i m e s ( r ) f o r l a c t o n e - e s t e r 96 a n d t h e d i e s t e r 9 3 c . I n t h e p r e s e n t s t u d i e s , 2 , 5 - d i m e t h y l - 2 , 4 - h e x a d i e n e a n d 1 , 3 - c y c l o h e x a d i e n e w i t h t r i p l e t 89 e n e r g i e s o f 59 k c a l / m o l e a n d 53 k c a l / m o l r e s p e c t i v e l y w e r e u s e d a s t h e t r i p l e t q u e n c h e r s . A l t h o u g h t h e t r i p l e t e n e r g i e s f o r c o m p o u n d s 96 a n d 9 3 c a r e n o t k n o w n , i t i s e s t i m a t e d t h a t b o t h c o m p o u n d s h a v e t h e i r t r i p l e t e n e r g i e s i n t h e r a n g e 6 0 - 7 0 k c a l / m o l . T h i s i s b a s e d o n t h e e x p e r i m e n t a l r e s u l t s t h a t t h e d i - j r - m e t h a n e r e a r r a n g e m e n t ( t r i p l e t r e a c t i o n ) o f c o m p o u n d s 96 a n d 9 3 c c o u l d b e q u e n c h e d b y 2 , 5 - d i m e t h y l - 2 , 4 -h e x a d i e n e ( E ^ = 59 k c a l / m o l e ) o r 1 , 3 - c y c l o h e x a d i e n e (E- j = 53 k c a l / m o l e ) , 89 a n d c o u l d a l s o p h o t o s e n s i t i z e d b y b e n z o p h e n o n e ( E f = 69 k c a l / m o l e ) . T h e r e l a t i v e q u a n t u m y i e l d s ( $ 0 / $ ) w e r e d e t e r m i n e d u n d e r v a r i o u s - 145 -c o n c e n t r a t i o n s o f t h e q u e n c h e r . A c c o r d i n g t o t h e S t e r n - V o l m e r e q u a t i o n s h o w n a s f o l l o w s , c h a n g e s o f $0/$ a s a f u n c t i o n o f t h e q u e n c h e r c o n c e n t r a t i o n s o b e y a l i n e a r r e l a t i o n s h i p . $o/$ - 1 + k qr[Q] W h e r e $ a n d <J>0 a r e t h e q u a n t u m y i e l d s w i t h a n d w i t h o u t t h e q u e n c h e r , k q i s t h e b i m o l e c u l a r q u e n c h i n g r a t e c o n s t a n t , T i s t h e l i f e t i m e o f t h e e x c i t e d s t a t e b e i n g q u e n c h e d a n d [Q] i s t h e q u e n c h e r c o n c e n t r a t i o n . I n t h e c a s e o f t h e l a c t o n e - e s t e r 9 6 , t h e e x p e r i m e n t a l d a t a w e r e i n g o o d a g r e e m e n t w i t h t h e S t e r n - V o l m e r e q u a t i o n . P l o t t i n g t h e q u a n t u m y i e l d s ( $ 0 / $ ) a g a i n s t t h e c o n c e n t r a t i o n o f t h e q u e n c h e r ( 2 , 5 - d i m e t h y l -2 , 4 - h e x a d i e n e ) r a n g i n g f r o m 0 - 0 . 0 4 M , g a v e a s t r a i g h t l i n e s h o w n i n F i g u r e 2 4 . F r o m t h e s l o p e o f t h e l i n e , t h e k q r v a l u e i s c a l c u l a t e d t o b e 105 ± 5 M"^". B y a s s u m i n g d i f f u s i o n c o n t r o l l e d e n e r g y t r a n s f e r f r o m t h e e x c i t e d t r i p l e t o f c o m p o u n d 96 t o t h e q u e n c h e r , a n d b y u s i n g t h e r a t e o f 9 - 1 - 1 9 4 d i f f u s i o n i n b e n z e n e a s k q = 5 . 0 x 10 M s , we a r r i v e a t a r e l a t i v e l y l o n g t r i p l e t l i f e t i m e o f 21 ± 2 n s f o r t h e l a c t o n e - e s t e r 9 6 . T h e q u e n c h i n g p r o c e s s i s c o n s i d e r e d t o o b e y t h e f o l l o w i n g g e n e r a l m e c h a n i s m ( S c h e m e 5 8 ) . 146 A - - - - - V V + Q - — V + A S c h e m e 58 G e n e r a l T r i p l e t Q u e n c h i n g M e c h a n i s m . E x c i t a t i o n o f t h e r e a c t a n t ( A ) b y a b s o r p t i o n a p h o t o n l e a d s t o t h e 1 * e x c i t e d s i n g l e t s t a t e ( A ) w h i c h u n d e r g o e s i n t e r s y s t e m c r o s s i n g t o g i v e 3 * 3 * t h e e x c i t e d t r i p l e t s t a t e ( A ) . E n e r g y t r a n s f e r f r o m A t o t h e g r o u n d s t a t e q u e n c h e r (Q) r e s u l t s i n t h e g r o u n d s t a t e o f t h e r e a c t a n t ( A ) a n d t h e e x c i t e d t r i p l e t s t a t e o f t h e q u e n c h e r (Q) . Oo/O [Q] X 10 (M) F i g u r e 2 4 A S t e r n - V o l m e r P l o t f o r F o r m a t i o n o f D i b e n z o s e m i b u l l v a l e n e L a c t o n e 1 5 3 f r o m L a c t o n e - E s t e r 96 i n t h e P r e s e n c e o f 2 , 5 -D i m e t h y l - 2 , 4 - h e x a d i e n e . 147 However, i t was found that 1:1 adducts between the lactone-ester 96 and the quencher 2 ,5-dimethyl -2 ,4-hexadiene or 1,3-cyclohexadiene were formed i n s i g n i f i c a n t amounts. Further experiments suggest that the cyc l o a d d i t i o n reactions of the lactone-ester 96 to the quenchers might occur from the excited t r i p l e t state of the quenchers (see the discussion i n the next s e c t i o n ) . In contrast . to the lactone-ester 96, i t was found that the di-jr-methane rearrangement of the d i e s t e r 93c was i n e f f i c i e n t l y quenched by 1,3-cyclohexadiene i n the concentration range 0 - 1.0 M. By the Stern-Volmer analysis (Figure 25), kqr i s determined to be 0.59 ± 0.02 M"^ ". Again, assuming d i f f u s i o n c o n t r o l l e d energy trans f e r and using the rate 9 1 1 94 of d i f f u s i o n i n benzene as kq = 5.0 x 10 M s , the t r i p l e t l i f e t i m e r i s c a l c u l a t e d to be 0.12 ± 0.01 ns. 1.8 0.6 H 1 i I 1 1 1 I < I « 1 1 r — I 1 1 1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 [Q] (M) Figure 25 A Stern-Volmer Plot for Formation of Dibenzosemibullvalenes 120 and 124 from 93c i n the Presence of 1,3-Cyclohexadiene. 148 I t i s i n t e r e s t i n g t o c o m p a r e t h e t r i p l e t l i f e t i m e s o f t h e l a c t o n e -e s t e r 96 ( r = 21 n s ) a n d t h e d i e s t e r 9 3 c (T = 0 . 1 2 n s ) w i t h t h o s e d e t e r m i n e d b y o t h e r s a s s h o w n i n T a b l e 1 3 . F i r s t , i t c a n b e n o t e d t h a t t h e d i b e n z o b a r r e l e n e d i e s t e r 9 3 c h a s a p p r o x i m a t e l y t h e s a m e s h o r t t r i p l e t l i f e t i m e a s t h o s e c o m p o u n d s l i s t e d i n T a b l e 1 3 . I n c o n t r a s t , h o w e v e r , t h e t r i p l e t l i f e t i m e o f t h e l a c t o n e - e s t e r 96 i s r e m a r k a b l y l o n g e r ( c a . 1 8 0 - f o l d ) t h a n t h e d i e s t e r 9 3 c a n d o t h e r s i m i l a r c o m p o u n d s i n T a b l e 1 3 . T h e r e a s o n f o r s u c h a r e m a r k a b l e d i f f e r e n c e i n t r i p l e t l i f e t i m e s b e t w e e n c o m p o u n d s 96 a n d 9 3 c i s n o t i m m e d i a t e l y c l e a r , a s we k n o w t h a t t r i p l e t l i f e t i m e ( r ) i s d e t e r m i n e d b y t h e f o l l o w i n g e q u a t i o n : • r = 1 / ( k d + k p + k r ) w h e r e k^ a n d k p a r e r a t e c o n s t a n t s o f r a d i a t i o n l e s s d e c a y a n d p h o s p h o r e s c e n c e f r o m t h e e x c i t e d t r i p l e t s t a t e . I n p r i n c i p l e , t h e r e a c t i o n r a t e c o n s t a n t s ( k r ) c o u l d b e c a l c u l a t e d a c c o r d i n g t o t h e a b o v e e q u a t i o n . H o w e v e r , we d o n o t k n o w t h e v a l u e s o f r a t e c o n s t a n t s k d a n d k p , a n d t h i s p r e v e n t s u s f r o m f u r t h e r s p e c u l a t i o n o n t h e d i f f e r e n c e i n p h o t o r e a c t i v i t y b e t w e e n c o m p o u n d s 96 a n d 9 3 c i n t h e d i - w - m e t h a n e p h o t o r e a r r a n g e m e n t . E . P h o t o c y c l o a d d i t i o n s o f L a c t o n e - e s t e r 96 t o 1 , 3 - D i e n e s P h o t o c y c l o a d d i t i o n s h a v e l o n g b e e n t h e s u b j e c t o f r e s e a r c h i n t e r e s t i n t h e f i e l d o f o r g a n i c p h o t o c h e m i s t r y w i t h r e g a r d t o t h e i r a p p l i c a t i o n s a n d m e c h a n i s m . [2+2] P h o t o c y c l o a d d i t i o n s o f a w i d e v a r i e t y - 149 o f o r g a n i c c o m p o u n d s s u c h a s a l k e n e s , s a t u r a t e d a n d u n s a t u r a t e d k e t o n e s h a v e b e e n s t u d i e d e x t e n s i v e l y o v e r t h e p a s t s e v e r a l d e c a d e s . 1 , 3 - D i e n e s a r e c o m m o n l y u s e d a s e f f i c i e n t t r i p l e t q u e n c h e r s i n t h e p h o t o r e a c t i o n s o f a l k a n o n e s a n d a . / S - u n s a t u r a t e d k e t o n e s . O n t h e o t h e r h a n d , 1 , 3 - d i e n e s c a n a l s o p a r t i c i p a t e i n p h o t o c y c l o a d d i t i o n r e a c t i o n s t o g i v e [2+2] a n d [4+2 ] a d d u c t s . E x a m p l e s o f t h i s t y p e o f p h o t o a d d i t i o n a r e f o u n d i n S c h e m e 5 9 . T h e r e a c t i o n i s u s u a l l y c o n s i d e r e d t o o c c u r f r o m t h e m o l e c u l e s t h a t a r e d i r e c t l y e x c i t e d b y a b s o r p t i o n o f a p h o t o n . H o w e v e r , i t i s p o s s i b l e t h a t , i f t h e e x c i t e d m o l e c u l e s s u c h a s c o m p o u n d s 182 a n d 1 8 4 ( E ^ > 60 k c a l / m o l ) i n S c h e m e 59 a r e c a p a b l e o f t r a n s f e r r i n g t h e i r e n e r g y t o t h e d i e n e s ( E ^ = 5 3 - 6 0 k c a l / m o l ) , t h e c y c l o a d d i t i o n r e a c t i o n c o u l d o c c u r f r o m t h e e x c i t e d t r i p l e t s t a t e o f t h e d i e n e s . S u c h p r o c e s s e s 95 96 97 h a v e b e e n r e p o r t e d . ' ' I n a d d i t i o n , t h e p h o t o c y c l o a d d i t i o n o f m a l e i c a n h y d r i d e 183 t o t r i p l e t 1 , 3 - d i e n e s , w h i c h w e r e i n d i r e c t l y 98 e x c i t e d b y b e n z o p h e n o n e - s e n s i t i z a t i o n , h a s b e e n r e p o r t e d ( S c h e m e 5 9 ) . I n o u r q u e n c h i n g s t u d i e s o n t h e l a c t o n e - e s t e r 9 6 , we f o u n d t h a t 1 , 3 - d i e n e s n o t o n l y q u e n c h t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f 96 b u t a l s o f o r m 1 :1 a d d u c t s w i t h i t . Two 1 , 3 - d i e n e s , n a m e l y 2 , 5 - d i m e t h y l - 2 , 4 -h e x a d i e n e a n d 1 , 3 - c y c l o h e x a d i e n e , w e r e u s e d i n t h e s t u d i e s o f p h o t o c y c l o a d d i t i o n s o f 96 t o d i e n e s . - 1 5 0 -S c h e m e 59 P h o t o c y c l o a d d i t i o n s o f 1 , 3 - D i e n e s . 1 . C y c l o a d d i t i o n o f L a c t o n e - e s t e r 96 t o 2 , 5 - D i m e t h y l - 2 , 4 - h e x a d i e n e A m i x t u r e o f t h e l a c t o n e - e s t e r 96 a n d 2 , 5 - d i m e t h y l - 2 , 4 - h e x a d i e n e ( r a t i o = 1 : 4 ) i n b e n z e n e w a s i r r a d i a t e d t h r o u g h a P y r e x f i l t e r (A > 290 nm) u n t i l m o r e t h a n 95% o f t h e s t a r t i n g m a t e r i a l w a s c o n v e r t e d . C o l u m n c h r o m a t o g r a p h y y i e l d e d t h e r e a r r a n g e d p r o d u c t 1 5 3 , t h e [2+2] a d d u c t 185 151 a n d t h e 1 : 1 m i x t u r e o f a d d u c t s 185 a n d 186 ( S c h e m e 6 0 ) . GC a n a l y s i s s h o w e d t h a t t h e a d d u c t 185 i s t h e m a j o r [2+2] p h o t o c y c l o a d d i t i o n p r o d u c t (GC r a t i o 1 5 3 : 1 8 5 : 1 8 6 = 1 : 1 . 6 : 1 ) . T h e s t r u c t u r e s o f t h e [2+2] p h o t o a d d u c t s 185 a n d 1 8 6 w e r e d e t e r m i n e d b y MS o r GCMS a s w e l l a s b y F T I R a n d ''"H NMR s p e c t r a . T h e r e g i o - a n d s t e r e o c h e m i s t r y o f t h e s t r u c t u r e s w e r e a s s i g n e d b a s e d p r i m a r i l y o n r o u t i n e ''"H NMR, p r o t o n d e c o u p l i n g a n d N O E e x p e r i m e n t s . 0 185 1 8 6 S c h e m e 60 [2+2] P h o t o c y c l o a d d i t i o n o f L a c t o n e - E s t e r 96 t o 2 , 5 -D i m e t h y l - 2 , 4 - h e x a d i e n e . T h e a d d u c t 185 i s c h a r a c t e r i z e d i n f o r m a t i v e l y b y "^H NMR ( F i g u r e 2 6 ) a s f o u r h i g h - f i e l d s i n g l e t s , 5 = 1 . 0 7 , 1 . 1 6 , 1 . 2 2 a n d 1 . 6 4 p p m , w h i c h c o r r e s p o n d t o t h e f o u r n o n - e s t e r m e t h y l g r o u p s . Two o f t h e m e t h y l s i g n a l s (5 «= 1 . 2 2 a n d 1 . 6 4 ppm) a r e s e e n t o b e w e a k l y c o u p l e d w i t h t h e v i n y l h y d r o g e n a t o m ( J < 1 H z ) . T h e s t r u c t u r a l a s s i g n m e n t o f t h e - 152 r e g l o c h e m i s t r y o f 185 i s s u p p o r t e d b y t h e NOE d i f f e r e n c e m e a s u r e m e n t ( F i g u r e 2 6 ) . I r r a d i a t i o n o f t h e m e t h y l g r o u p ( a C H 3 o f s t r u c t u r e 1 8 5 i n F i g u r e 2 7 ) r e s u l t s i n t h e s i g n a l e n h a n c e m e n t o f t h e b r i d g e h e a d p r o t o n . M o l e c u l a r m o d e l o f c o m p o u n d 1 8 5 s h o w s t h a t t h e m e t h y l g r o u p ( a C H 3 ) i s c l o s e t o t h e b r i d g e h e a d h y d r o g e n a t o m , a n d t h i s i s i n a g r e e m e n t w i t h t h e N O E r e s u l t s . F i g u r e 26 P a r t i a l H NMR S p e c t r a o f P h o t o a d d u c t 1 8 5 . B o t t o m : r o u t i n e s p e c t r u m . T o p a n d m i d d l e : NOE d i f f e r e n c e a f t e r i r r a d i a t i o n . - 1 5 3 -E = C O 2 C H 3 F i g u r e 27 S t r u c t u r a l I n f o r m a t i o n o f P h o t o a d d u c t s 185 a n d 1 8 6 . T h e s t r u c t u r e o f t h e a d d u c t 186 i s a l s o a s s i g n e d b a s e d o n a n N O E e x p e r i m e n t o f t h e p h o t o p r o d u c t m i x t u r e , 185 a n d 1 8 6 . P a r t i a l NMR d a t a a r e p r e s e n t e d i n F i g u r e 2 8 . A g a i n , s a t u r a t i o n o f t h e r e s o n a n c e (5 = 1 . 1 3 ppm) o f t h e h i g h - f i e l d m e t h y l g r o u p s i g n a l ( a C H 3 o f t h e s t r u c t u r e 1 8 6 i n F i g u r e 2 7 ) l e a d s t o a s i g n a l e n h a n c e m e n t o f t h e b r i d g e h e a d h y d r o g e n a t o m . T h i s i n f o r m a t i o n s u p p o r t s t h e a s s i g n m e n t o f t h e r e g i o c h e m i s t r y o f p r o d u c t 1 8 6 . R e g a r d i n g t h e s t e r e o c h e m i s t r y o f t h e [2+2] a d d u c t s 185 a n d 1 8 6 , t h e c h e m i c a l s h i f t s o f t h e v i n y l p r o t o n a n d t h e c y c l o b u t y l p r o t o n w e r e u s e d t o d i s t i n g u i s h t h e t w o s t e r e o i s o m e r s . I n t h e c a s e o f i s o m e r 1 8 5 , t h e v i n y l h y d r o g e n a t o m i s f o u n d t o r e s o n a t e a t 6 — 5 . 1 4 p p m , a n d t h e c h e m i c a l s h i f t o f t h e c y c l o b u t y l h y d r o g e n a t o m i s a t 5 = 2 . 1 4 p p m . I n c o n t r a s t , t h e s t e r e o i s o m e r 186 g i v e s a r e l a t i v e l y h i g h - f i e l d d o u b l e t f o r t h e v i n y l h y d r o g e n a t o m a t 3 . 4 0 ppm a n d t h e c y c l o b u t y l p r o t o n r e s o n a t e s a t 6 = 3 . 0 5 p p m . I t c a n b e s e e n c l e a r l y f r o m m o l e c u l a r m o d e l s t h a t t h e c y c l o b u t y l h y d r o g e n a t o m f r o m 1 8 5 l i e s i n t h e s h i e l d i n g r e g i o n o f t h e - 154 -a r o m a t i c r i n g , t h u s t h e r e s o n a n c e o f t h i s p r o t o n i s f o u n d a t r e l a t i v e l y h i g h - f i e l d (8 = 2 . 1 4 ppm) c o m p a r e d t o t h a t i n t h e i s o m e r 1 8 6 (5 = 3 . 0 5 ppm) . A s i m i l a r s i t u a t i o n e x i s t s i n t h e c a s e o f i s o m e r 1 8 6 w h e r e t h e v i n y l h y d r o g e n r e s o n a t e s a t 8 •= 3 . 4 0 p p m o w i n g t o t h e s h i e l d i n g e f f e c t f r o m t h e a r o m a t i c s , c o m p a r e d t o t h a t o f 1 8 5 (8 = 5 . 1 4 ppm) w h i c h f a l l s i n t o t h e n o r m a l r e g i o n f o r u n s h i e l d e d v i n y l p r o t o n s . F i g u r e 28 P a r t i a l H NMR S p e c t r a o f P h o t o a d d u c t 1 8 6 . B o t t o m : r o u t i n e s p e c t r u m . T o p : NOE d i f f e r e n c e a f t e r i r r a d i a t i o n . - 155 -The stereochemical assignment of photoproduct 185 i s also supported by the NOE observation (Figure 26). I r r a d i a t i o n of the methyl group (kfJH3 of 185 i n Figure 27) leads to a s i g n a l enhancement of the cyc l o b u t y l hydrogen atom, which i s considered to be c i s to t h i s methyl group. 2. Cycloaddition of Lactone-Ester 96 to 1,3-Cyclohexadiene In a s i m i l a r fashion, photolysis of a mixture of the lactone-ester 96 and 1,3-cyclohexadiene ( r a t i o 1:12) was performed and shown to give the compounds 187, 188, 189 and 190 (GC r a t i o = 11:3:1:2) (Scheme 61). Although traces of other photoproducts were detected by GC analysis of the reaction mixture, they could not be i s o l a t e d owing to the small amounts present. 0 O + CO2CH3 187 E O 0 188 189 190 Scheme 61 Photocycloaddition of Lactone-Ester 96 to 1,3-Cyclohexadiene . - 1 5 6 -T h e m a j o r [2+2] p h o t o c y c l o a d d i t i o n a d d u c t 187 w a s i s o l a t e d i n p u r e 1 1 o c r y s t a l l i n e f o r m a n d f u l l y c h a r a c t e r i z e d b y H a n d X J C NMR, F T I R a n d MS s p e c t r o s c o p y . T h e F T I R s p e c t r u m o f 1 8 7 s h o w s t w o c h a r a c t e r i s t i c c a r b o n y l a b s o r p t i o n s , 1 7 8 0 c m " x a n d 1 7 2 3 c m _ i , w h i c h c o r r e s p o n d t o t h e f u n c t i o n a l g r o u p s o f t h e s a t u r a t e d l a c t o n e a n d t h e e s t e r . T h e a s s i g n m e n t o f t h e s t r u c t u r e 1 8 7 w a s b a s e d p r i m a r i l y o n X H NMR s p e c t r o s c o p y . T h e p r o t o n d e c o u p l e d , N O E d i f f e r e n c e a n d 2D C O S Y A H NMR s p e c t r a o f 1 8 7 a r e g i v e n i n F i g u r e s 30 t o 3 2 . C o m p o u n d 187 i s c h a r a c t e r i z e d i n i t s X H NMR s p e c t r u m ( F i g u r e 3 0 ) b y two v i n y l p r o t o n s a t 6 = 5 . 7 7 a n d 5 . 9 0 p p m . A s e t o f two d o u b l e t s a t 5 = 4 . 8 7 a n d 5 . 3 0 ppm w a s a s s i g n e d t o t h e l a c t o n e m e t h y l e n e h y d r o g e n a t o m s . T h e b r i d g e h e a d p r o t o n r e s o n a t e s a t 5 = 4 . 6 6 p p m , a n d t h e e s t e r m e t h y l s i n g l e t w a s f o u n d a t 5 = 3 . 4 2 p p m . I n a d d i t i o n , m u l t i p l e t s a t t h e r e g i o n 1 . 4 - 2 . 4 ppm w e r e a s c r i b e d t o t h e p r o t o n s t h a t a t t a c h e d t o t h e c y c l o h e x e n e r i n g . O n e o f t h e c y c l o b u t y l h y d r o g e n a t o m s , H a a s s h o w n i n t h e s t r u c t u r e 187 i n F i g u r e 2 9 , i s a s s i g n e d t o b e a d j a c e n t t o t h e v i n y l g r o u p b y t h e f o l l o w i n g e v i d e n c e : a s s h o w n b y t h e d e c o u p l e d s p e c t r a i n F i g u r e 3 0 , t h e m u l t i p l e t f r o m t h e v i n y l p r o t o n (H^ ) i s c h a n g e d t o a d o u b l e t a f t e r t h e s i g n a l H a a t S = 2 . 3 1 i s d e c o u p l e d ; t h i s d o u b l e t i s d u e t o t h e c o u p l i n g o f w i t h t h e o t h e r v i n y l p r o t o n ( H c ) . I n t u r n , t h e m u l t i p l e t d u e t o H a b e c o m e s a d o u b l e t w h e n i s i r r a d i a t e d . B a s e d o n t h i s a s s i g n m e n t , t h e r e m a i n i n g h y d r o g e n a t o m s i n t h e r e g i o n 1 . 4 - 2 . 4 ppm a r e a s s i g n e d a c c o r d i n g l y b y t h e d e c o u p l e d a n d 2D C O S Y X H NMR s p e c t r a ( F i g u r e s 30 a n d 3 1 ) , w h i c h n e e d n o t b e d i s c u s s e d f u r t h e r . F i n a l c o n f i r m a t i o n o n t h e s t r u c t u r e o f 187 c o m e s f r o m t h e N O E d i f f e r e n c e o b s e r v a t i o n s ( F i g u r e 3 2 ) , i n w h i c h i r r a d i a t i o n o f t h e c y c l o b u t y l h y d r o g e n a t o m ( H a ) l e a d s t o a s i g n a l e n h a n c e m e n t o f t h e b r i d g e h e a d p r o t o n ( H e ) , w h e r e a s i r r a d i a t i o n o f t h e o t h e r c y c l o b u t y l h y d r o g e n a t o m - 157 (H^-,) r e s u l t s i n t h e s i g n a l e n h a n c e m e n t o f o n e o f t h e l a c t o n e m e t h y l e n e h y d r o g e n a t o m s . T h e m o l e c u l a r m o d e l o f 187 s h o w s t h a t t h e c y c l o b u t y l h y d r o g e n a t o m ( H a ) i s s p a t i a l l y c l o s e r t o t h e b r i d g e h e a d h y d r o g e n a t o m ( H e ) , a n d i s c l o s e r t o o n e o f t h e l a c t o n e m e t h y l e n e p r o t o n s . H e H e  1 8 7 E = C O 2 C H 3 1 8 8 F i g u r e 29 S t r u c t u r a l A s s i g n m e n t o f t h e [2+2] A d d u c t s 187 a n d 1 8 8 . - 158 Figure 30 P a r t i a l lti NMR S p e c t r a o f P h o t o p r o d u c t 187. B o t t o m : r o u t i n e s p e c t r u m . M i d d l e : d e c o u p l e d a t 2 . 3 1 p p m . T o p : d e c o u p l e d a t 5 . 7 6 p p m . - 159 -Photoproduct 187 400 MHz 3.a J . s 2 .a i . s Figure 31 P a r t i a l 2D COSY H NMR Spectrum of Photoproduct 187. F i g u r e 32 P a r t i a l H NMR S p e c t r a o f P h o t o p r o d u c t 1 8 7 . B o t t o m : r o u t i n e s p e c t r u m . Top four:NOE d i f f e r e n c e a f t e r i r r a d i a t i o n . - 161 -A l t h o u g h t h e [2+2] a d d u c t 188 ( S c h e m e 6 1 ) w a s o b t a i n e d a s a m i x t u r e ( c a . 65% p u r e ) , i t c o u l d s t i l l b e c h a r a c t e r i z e d r e a d i l y b y NMR a n d G C - M S s p e c t r o s c o p y s i n c e t h e m i x t u r e c o n t a i n s t h e a d d u c t s 187 a n d 189 w h o s e s t r u c t u r e s a r e k n o w n ( s e e b e l o w f o r i d e n t i f i c a t i o n o f p h o t o p r o d u c t 1 8 9 ) . T h e "^H NMR s p e c t r u m o f 1 8 8 p r o v e d t o b e q u i t e s i m i l a r t o t h a t o f i t s r e g i o i s o m e r 1 8 7 , t h u s t h e s t r u c t u r e o f c o m p o u n d 1 8 8 i s a s s i g n e d i n m u c h t h e s a m e w a y a s t h a t o f 1 8 7 . I n p a r t i c u l a r , t h e m u l t i p l e t a t c a . 1 . 8 ppm i n F i g u r e 33 i s a s c r i b e d t o t h e c y c l o b u t y l h y d r o g e n a t o m o f s t r u c t u r e 188 ( F i g u r e 2 9 ) , w h i c h i s a d j a c e n t t o t h e d o u b l e b o n d . T h i s i s s u p p o r t e d b y d e c o u p l i n g e x p e r i m e n t s ( F i g u r e 33 ) , w h i c h s h o w t h a t i r r a d i a t i o n o f H c a t 8 = 5 . 2 5 ppm c h a n g e s t h e m u l t i p l e t t o a d o u b l e t . C o n v e r s e l y , i r r a d i a t i o n o f H b c o n v e r t s t h e m u l t i p l e t d u e t o H c t o a d o u b l e t . T h e c y c l o b u t y l h y d r o g e n a t o m H a i s a s s i g n e d t o t h e r e s o n a n c e a t 2 . 2 ppm ( m u l t i p l e t ) , a s t h i s m u l t i p l e t ( H a ) b e c o m e s a q u a r t e t ( d u e t o c o u p l i n g b y t h e a d j a c e n t C H 2 ) w h e n i s i r r a d i a t e d . T h e r e g i o - a n d s t e r e o c h e m i s t r y o f a d d u c t 188 i s s u p p o r t e d b y t h e NOE e x p e r i m e n t s i n a f a s h i o n s i m i l a r t o t h a t d e s c r i b e d i n t h e c a s e o f r e g i o i s o m e r 1 8 7 . T h e NOE d i f f e r e n c e s p e c t r a o f p h o t o p r o d u c t 1 8 8 a s f o u n d i n F i g u r e 34 s h o w t h a t i r r a d i a t i o n o f t h e c y c l o b u t y l p r o t o n (H^) l e a d s t o a s i g n a l e n h a n c e m e n t o f o n e o f t h e l a c t o n e m e t h y l e n e h y d r o g e n a t o m s . I n c o n t r a s t , a n e n h a n c e m e n t o f t h e s i g n a l d u e t o t h e b r i d g e h e a d h y d r o g e n a t o m ( H e ) i s o b s e r v e d w h e n t h e s e c o n d c y c l o b u t y l h y d r o g e n a t o m ( H a ) i s s a t u r a t e d . T h e s e o b s e r v a t i o n s a r e i n a g r e e m e n t w i t h t h e a s s i g n m e n t o f t h e s t r u c t u r e 1 8 8 . - 162 F i g u r e 33 P a r t i a l i H NMR S p e c t r a o f P h o t o p r o d u c t 188. B o t t o m : r o u t i n e s p e c t r u m . M i d d l e : d e c o u p l e d a t 6 = 5 . 2 5 p p m . T o p : d e c o u p l e d a t 5 = 1 . 7 9 p p m . , ' , ' ' ' ' i 1 i ' — i — 1 — i — 1 — r — • — i • I • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — • — i — ' — i — ' — i — ' — I — • — t — 1 — r -' • " S.J B.6 6.1 8.2 8.0 5.8 5.6 5.1 5.1 5.8 1.8 l . i I . I 1.2 I.a J.B J.S J, I J . 2 J.t 2.8 2.8 J . I 2.2 2.t l . » Figure 34 P a r t i a l 1 H NMR S p e c t r a o f P h o t o p r o d u c t 188. B o t t o m : r o u t i n e s p e c t r u m . T o p a n d m i d d l e : NOE d i f f e r e n c e a f t e r i r r a d i a t i o n . 164 -T h e p h o t o - a d d u c t 189 ( S c h e m e 6 1 ) i s c h a r a c t e r i z e d i n i t s F T I R s p e c t r u m b y two s t r o n g c a r b o n y l a b s o r p t i o n b a n d s a t 1 7 7 7 cm"''" a n d 1 7 2 3 c m " 1 , w h i c h a r e a s c r i b e d t o t h e s a t u r a t e d l a c t o n e a n d e s t e r g r o u p s . T h e 1 , 4 - c y c l o h e x a d i e n e m o i e t y i s i d e n t i f i e d b y f o u r s e t s o f m u l t i p l e t s a t 6 = 5 . 7 1 , 5 . 9 9 , 6 . 0 5 a n d 6 . 1 4 ppm i n t h e 1 H NMR s p e c t r u m ( F i g u r e 3 5 ) . T h e CH2 g r o u p o f t h e 1 , 4 - c y c l o h e x a d i e n e m o i e t y i s f o u n d a t 5 = 2 . 5 8 ppm a s a m u l t i p l e t , a n d t h e m u l t i p l e t a t S = 2 . 8 3 ppm i s a s s i g n e d t o t h e m e t h i n e h y d r o g e n a t o m o f t h e c y c l o h e x a d i e n e . T h e p o s s i b i l i t y t h a t t h i s m a t e r i a l h a s t h e 1 , 3 - c y c l o h e x a d i e n e s t r u c t u r e 1 9 1 ( F i g u r e 3 6 ) h a s b e e n e l i m i n a t e d o n t h e f o l l o w i n g b a s i s : ( 1 ) t h e e x p e c t e d v i c i n a l p r o t o n c o u p l i n g b e t w e e n t h e m e t h y l e n e a n d t h e m e t h i n e h y d r o g e n a t o m s f o r t h e 1 , 3 - c y c l o h e x a d i e n y l g r o u p i s n o t o b s e r v e d i n t h e X H NMR s p e c t r u m ; a n d ( 2 ) a s s h o w n i n F i g u r e 3 5 , two o f t h e m u l t i p l e t s c o r r e s p o n d i n g t o t h e v i n y l p r o t o n s (5 = 5 . 7 1 a n d 5.99 ppm) b e c o m e d o u b l e t s w h e n t h e c y c l o h e x a d i e n y l m e t h y l e n e h y d r o g e n a t o m s (5 = 2 . 5 7 ppm) a r e i r r a d i a t e d . F u r t h e r m o r e , t h e o t h e r two m u l t i p l e t s f o r v i n y l p r o t o n s b e c o m e d o u b l e t s u p o n d e c o u p l i n g o f t h e c y c l o h e x a d i e n y l m e t h i n e p r o t o n (H]-,) . T h e s e r e s u l t s s u g g e s t t h a t t h e m e t h y l e n e a n d m e t h i n e p r o t o n s a r e b o t h a d j a c e n t t o two v i n y l g r o u p s . T h e d e c o u p l i n g r e s u l t s a r e t h e r e f o r e i n c o n s i s t e n t w i t h t h e 1 , 3 -c y c l o h e x a d i e n y l s t r u c t u r e 1 9 1 . T h e a s s i g n m e n t o f t h e r e g i o - a n d s t e r e o c h e m i s t r y t o s t r u c t u r e 1 8 9 i s s u p p o r t e d b y t h e N O E d i f f e r e n c e e x p e r i m e n t s ( F i g u r e 3 7 ) . I r r a d i a t i o n o f t h e a - h y d r o g e n a t o m ( H a ) w h i c h i s a d j a c e n t t o t h e l a c t o n e c a r b o n y l l e a d s t o a n e n h a n c e m e n t o f t h e s i g n a l o f o n e o f t h e l a c t o n e m e t h y l e n e p r o t o n s . A m o l e c u l a r m o d e l o f c o m p o u n d 189 s h o w s t h a t H a i s i n c l o s e p r o x i m i t y t o t h e l a c t o n e m e t h y l e n e h y d r o g e n a t o m . A s e c o n d i r r a d i a t i o n a t t h e c y c l o h e x a d i e n y l m e t h i n e h y d r o g e n a t o m ( H D , 6 = 2 . 8 3 ppm) r e s u l t s i n a n e n h a n c e m e n t o f 165 -t h e s i g n a l d u e t o H a , w h i c h i n d i c a t e s t h a t t h e 1 , 4 - c y c l o h e x a d i e n y l g r o u p i s cis t o t h e m e t h i n e h y d r o g e n a t o m H a . F i g u r e 35 P a r t i a l NMR S p e c t r a o f P h o t o p r o d u c t 1 8 9 . B o t t o m : r o u t i n e s p e c t r u m . M i d d l e : d e c o u p l e d a t 8 = 2 . 5 7 p p m . T o p : d e c o u p l e d a t 6 = 2 . 8 3 p p m . 166 -Figure 36 189 191 E - C02CH3 Structures of Photoproduct 189 and I t s Isomer 191 189 1 l i > i « 11 X <•. E - C O 2 C H 3 —t—•—1—•—r—>—1—>—1—•—1—•—1—1—1—•—1—•—1—•—1—'—1—•—r—•*—-1—•—1 " T " T — 1 'i""rM—1—•—1—•—1—•—1—•—i——1—>—1—•—r~ 7 . 2 7 . 1 6 . 8 6 . E 6 . ' 6 . 2 6 . 1 5 . 6 5 . 6 5 . * 5 . 2 5 . 8 * . B 4 . 6 l . i 4 . 2 4 . 8 3 . 6 3 . 6 3 . ' 3 . 2 3.1 2 . 6 2 . 6 2 . * 2.2 PPM 7.6 7.6 7.1 A -> r — — 1 — • — 1 — • — 1 — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — 1 — • — r — • — 1 — • — 1 — • — 1 — ' — 1 — • — 1 — • — i ~ 7 . 2 7 . 8 6 . 6 6 . 6 6 . * 6 . 2 6.1 5 . 8 5 . 6 5 . 1 S . 2 S.I ' . 8 1 . 6 * . * ( . 2 4 . 8 3 . 8 3 . 6 3 . 4 3 . 2 3.1 2 . 8 2 . 6 2 . 4 2 . 2 7 . 8 7 . 6 7 . 4 400MHz JUUJ 'UJL_ r 1 ' ' ' — 1 — • — 1 — • — ' — • — 1 — r — 1 1 "• 'i—•—1—•—1—•—1—•—1—•—1—•—1—•—1—•—1—•—1—•—1—•—1—•—1—'—r — 1 1 T T 1 * T—•—r——r—•—1— 7 . 6 7 . 6 7 . 4 7.2 7.1 6 . 6 6 . 6 G . I 6 . 2 6 . 8 5 . 8 5 . 6 S . I S . 2 S.I 4 . 8 4 . 6 4 . 4 4 . 2 4 . 8 3 . 8 3 . 6 3 . 4 3 . 2 3.6 2 . 8 2 . 6 2 . 4 2 . 2 PPM Figure 37 P a r t i a l LE NMR Spectra of Photoproduct 189. Bottom: routine spectrum. Top and middle: NOE di f f e r e n c e a f t e r i r r a d i a t i o n . - 167 T h e r e d u c t i o n p r o d u c t 190 ( S c h e m e 6 1 ) w a s i d e n t i f i e d b y GCMS a n d •*"H NMR s p e c t r o s c o p y f r o m a m i x t u r e o f c o m p o u n d s 1 8 7 , 1 8 9 , 1 5 3 , a n d 1 9 0 ( c a . 60% o f 1 9 0 ) . GCMS a n a l y s i s o f c o m p o u n d 1 9 0 g a v e m / e = 3 2 0 a s t h e p a r e n t m a s s . I t i s a p p a r e n t t h a t r e d u c t i o n o f t h e l a c t o n e - e s t e r 96 b y t w o h y d r o g e n a t o m s h a d t a k e n p l a c e , a s i t s p a r e n t m a s s i s m / e = 3 1 8 . T h e trans s t e r e o c h e m i s t r y o f p h o t o p r o d u c t 1 9 0 i s c o n f i r m e d b y t h e ^"H NMR s p e c t r u m , w h i c h p r o v e d t o b e i d e n t i c a l t o t h a t r e p o r t e d b y O k a d a et a l . ^ " 0 ^ " i n t h e i r s t u d y o f t h e [4+2] p h o t o t r a n s f o r m a t i o n o f t h e a n t h r a c e n e d e r i v a t i v e 192 t o c o m p o u n d 1 9 0 ( S c h e m e 6 2 ) . 3 . M e c h a n i s t i c S t u d i e s o n t h e P h o t o c y c l o a d d i t i o n o f L a c t o n e - E s t e r 96 t o 1 , 3 - D I e n e s A s d i s c u s s e d i n t h e p r e v i o u s s e c t i o n o f t h i s t h e s i s , t h e di-7r-m e t h a n e p h o t o r e a r r a n g e m e n t o f t h e l a c t o n e - e s t e r 96 i s q u e n c h e d e f f i c i e n t l y b y 1 , 3 - c y c l o h e x a d i e n e o r 2 , 5 - d i m e t h y l - 2 , 4 - h e x a d i e n e , a n d t h e - 168 p h o t o c y c l o a d d i t i o n a d d u c t s b e t w e e n 96 a n d t h e d i e n e s w e r e i s o l a t e d . I n v i e w o f t h e m e c h a n i s m i n v o l v e d i n t h e [2+2] p h o t o c y c l o a d d i t i o n , we a r e i n t e r e s t e d i n t h a t w h e t h e r t h e r e a c t i o n s o c c u r f r o m t h e e x c i t e d t r i p l e t s t a t e o f t h e l a c t o n e - e s t e r 96 o r f r o m t h a t o f t h e 1 , 3 - d i e n e s . F i r s t , t h e p o s s i b i l i t y t h a t d i r e c t e x c i t a t i o n o f t h e 1 , 3 - d i e n e s i s i n v o l v e d i n t h e [2+2] c y c l o a d d i t i o n r e a c t i o n c a n b e r u l e d o u t , s i n c e t h e i r r a d i a t i o n w a s c a r r i e d o u t u n d e r t h e c o n d i t i o n o f u s i n g a P y r e x f i l t e r (A > 2 9 0 nm) . . U n d e r s u c h a r e a c t i o n c o n d i t i o n , 1 , 3 - d i e n e s w i l l n o t a b s o r b t h e l i g h t . I t i s a p p a r e n t t h a t t h e e x c i t e d t r i p l e t s t a t e o f c o m p o u n d 96 i s f o r m e d i n i t i a l l y t h r o u g h e x c i t a t i o n o f t h e l a c t o n e - e s t e r 96 b y a b s o r p t i o n o f a p h o t o n f o l l o w e d b y a r a p i d i n t e r s y s t e m c r o s s i n g p r o c e s s . F r o m t h e a b o v e , t h r e e p o s s i b l e m e c h a n i s m s c a n b e c o n s i d e r e d f o r t h e f o r m a t i o n o f t h e p h o t o c y c l o a d d u c t s : ( 1 ) L E + D -• a d d u c t s , ( 2 ) L E * + D ( L E - - D ) * • a d d u c t s a n d ( 3 ) L E * + D • L E + D * • a d d u c t s , w h e r e L E r e p r e s e n t s l a c t o n e - e s t e r 9 6 , D = 1 , 3 - d i e n e s a n d s t a n d s f o r t h e e x c i t e d s t a t e ( t r i p l e t ) . T h e f o l l o w i n g r e s u l t s s e e m t o s u g g e s t t h a t m e c h a n i s m s ( 3 ) i s p e r h a p s i n v o l v e d . T h a t i s , q u e n c h i n g t a k e s p l a c e f i r s t , a n d s u b s e q u e n t c y c l o a d d i t i o n o c c u r s f r o m t h e 1 , 3 - d i e n e t r i p l e t s . F i r s t o f a l l , i t w a s f o u n d t h a t t h e l a c t o n e - e s t e r 96 d i d n o t r e a c t w i t h 2 , 3 - d i m e t h y l - 2 - b u t e n e t o g i v e t h e [2+2] a d d u c t 193 ( S c h e m e 6 3 ) w h e n 96 a n d t h e a l k e n e ( r a t i o 1 : 1 0 ) w e r e i r r a d i a t e d . T h e o n l y p h o t o p r o d u c t o b s e r v e d i n t h i s c a s e w a s t h e r e a r r a n g e d d i b e n z o s e m i b u l l v a l e n e l a c t o n e 1 5 3 . B a s e d o n t h e g e n e r a l 102 p r e m i s e t h a t 2 , 3 - d i m e t h y l - 2 - b u t e n e i s k n o w n a s a f a i r l y r e a c t i v e s u b s t r a t e t o w a r d s [2+2] p h o t o c y c l o a d d i t i o n , o n e w o u l d e x p e c t t h a t t h i s - 169 -alkene would react with the excited t r i p l e t 96 to form [2+2] adducts i f the [2+2] c y c l o a d d i t i o n reaction i s capable of competing with the di-p-methane rearrangement. 96 ' 193 E = C O 2 C H 3 hv f 153 Scheme 63 Photolysis of Lactone-Ester 96 i n the Presence of 2,3-Dimethyl-2-butene. The quenching-cycloaddition mechanism (3) i s also supported by the s e n s i t i z a t i o n r e s u l t s . Photolysis of the lactone-ester 96 using t r i p l e t 89 s e n s i t i z e r s such as benzophenone (Ej; = 69 kcal/mol) or b e n z i l ( E j = 54 89 kcal/mol) i n the presence or absence of 1,3-cyclohexadiene (Ej = 53 kcal/mol) was c a r r i e d out at an i r r a d i a t i o n wavelength of A > 340 nm (uranium glass f i l t e r ) . Under the present i r r a d i a t i o n conditions, only the s e n s i t i z e r (benzophenone or benzil) i s excited. I t was found that, i n the absence of 1,3-cyclohexadiene, the di-7r-methane rearrangement of the lactone-ester 96 can be s e n s i t i z e d by benzophenone but not by b e n z i l . I t was also found that, i n the presence of the diene, the photolysis gives the expected cycloaddition products 187-190 with the 170 s a m e p r o d u c t r a t i o b y u s i n g e i t h e r b e n z o p h e n o n e o r b e n z i l a s t h e s e n s i t i z e r . T h i s p r o v i d e s e v i d e n c e t h a t e x c i t e d 1 , 3 - d i e n e s may p a r t i c i p a t e i n t h e p h o t o c y c l o a d d i t i o n r e a c t i o n w i t h t h e l a c t o n e - e s t e r 9 6 . I t s h o u l d b e p o i n t e d o u t , h o w e v e r , t h a t t h e e x c i p l e x m e c h a n i s m ( m e c h a n i s m ( 2 ) ) c o u l d n o t b e r u l e d o u t i n t h e p r e s e n t s t u d y . VI. S t u d i e s o n 9 - C h l o r o m e t h y l 9 , 1 0 - E t h e n o a n t h r a c e n e D i e s t e r 9 3 d T h e t i t l e c o m p o u n d , d i m e t h y l 9 - c h l o r o m e t h y l - 9 , 1 0 - d i h y d r o - 9 , 1 0 -e t h e n o a n t h r a c e n e - l l , 1 2 - d i c a r b o x y l a t e ( 9 3 d ) , was r e a d i l y p r e p a r e d b y D i e l s - A l d e r r e a c t i o n o f 9 - c h l o r o m e t h y l a n t h r a c e n e t o d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( S c h e m e '21 o n p a g e 4 2 ) . I t w a s i n t e r e s t i n g t o f i n d t h a t c o m p o u n d 9 3 d c r y s t a l l i z e s i n t h r e e d i f f e r e n t c r y s t a l l i n e m o d i f i c a t i o n s . F r o m d i e t h y l e t h e r / p e t r o l e u m e t h e r , n e e d l e a n d p r i s m c r y s t a l s o f 9 3 d w e r e f o r m e d . T h e two d i f f e r e n t l y s h a p e d c r y s t a l s w e r e s e p a r a t e d a n d s h o w n t o b e d i m o r p h i c b y t h e i r m e l t i n g p o i n t s a n d F T I R s p e c t r a . T h e n e e d l e c r y s t a l , w h i c h i s d e f i n e d a s t h e a - f o r m o f c r y s t a l l i n e c o m p o u n d 9 3 d , h a s a m e l t i n g p o i n t o f 1 7 4 - 1 7 6 ° C w h e r e a s t h e p r i s m c r y s t a l ( p ' - f o r m ) h a s a l o w e r m e l t i n g p o i n t o f 1 6 8 - 1 7 0 ° C . I t i s s h o w n i n F i g u r e 38 t h a t t h e F T I R s p e c t r a o f t h e d i m o r p h s a r e d i f f e r e n t i n t h e f i n g e r p r i n t r e g i o n . F i g u r e 38 F T I R S p e c t r a o f C r y s t a l l i n e 9 - C h l o r o m e t h y l d i b e n z o b a r r e l e n e 9 3 d . ( a ) Q - F o r m . ( b ) y S -Form ( c ) 7 - F o r m . - 172 -T h e a b o v e two p o l y m o r p h i c f o r m s w e r e a l s o c h a r a c t e r i z e d b y X - r a y c r y s t a l l o g r a p h i c a n a l y s i s . T h e a - f o r m w a s d e t e r m i n e d t o b e i n s p a c e g r o u p P2]2\2\\ i n c o n t r a s t , t h e / 3 - f o r m o c c u p i e s s p a c e g r o u p P 2 ] ^ / c . T h e ^ - c r y s t a l m o d i f i c a t i o n was a l s o a c h i e v e d b y r e c r y s t a l l i z a t i o n o f c o m p o u n d 9 3 d f r o m c h l o r o f o r m / m e t h a n o l . T h e t h i r d c r y s t a l m o d i f i c a t i o n ( 7 - f o r m ) was d e r i v e d b y r e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e . A l t h o u g h t h e 7 - t y p e c r y s t a l s ( p r i s m s ) o f 9 3 d h a v e t h e same m e l t i n g p o i n t ( 1 6 8 - 1 7 0 ° C ) a s t h e / 9 - t y p e , t h e i r F T I R s p e c t r a ( F i g u r e 3 8 ) a r e s l i g h t l y d i f f e r e n t f r o m t h o s e o f e i t h e r t h e a - f o r m o r t h e / 3 - f o r m c r y s t a l s . T h e 7 - t y p e c r y s t a l s a l s o o c c u p y t h e s p a c e g r o u p P 2 ^ / c ( s a m e a s t h a t o f t h e / 3 - f o r m ) , b u t w i t h d i f f e r e n t c e l l d i m e n s i o n s f r o m t h e / 3 - f o r m ( s e e E x p e r i m e n t a l f o r d e t a i l s ) . T h e u n i q u e n e s s o f 7 - c r y s t a l m o d i f i c a t i o n was a l s o s u p p o r t e d b y i t s d i f f e r e n t p h o t o c h e m i c a l a n d p h o t o p h y s i c a l b e h a v i o r c o m p a r e d t o t h e o t h e r t w o m o d i f i c a t i o n s . I t i s w e l l u n d e r s t o o d t h a t c r y s t a l l i n e p o l y m o r p h s may d i f f e r f r o m o n e a n o t h e r n o t o n l y i n t h e i r p a c k i n g a r r a n g e m e n t s b u t a l s o i n s u b t l e 103 v a r i a t i o n s i n t h e c o n f o r m a t i o n s o f t h e c o n s t i t u e n t m o l e c u l e s . I n s u c h c a s e s , o n e i s p r o v i d e d w i t h a n o p p o r t u n i t y t o s t u d y t h e s a m e r e a c t i o n i n m o r e t h a n o n e c r y s t a l m o d i f i c a t i o n . T h u s , a n y d i f f e r e n c e s i n r e a c t i v i t y a n d s e l e c t i v i t y t h a t a r e o b s e r v e d b e t w e e n p o l y m o r p h s may b e a s c r i b e d t o t h e s t r u c t u r a l ( b o t h m o l e c u l a r a n d c r y s t a l l o g r a p h i c ) d i f f e r e n c e s , t h e r e b y p r o v i d i n g m o r e i n f o r m a t i o n o n t h e s t r u c t u r e - r e a c t i v i t y c o r r e l a t i o n s . - 173 -A. Unusual Photorearrangement of 9-Chloromethyl Dibenzobarrelene Diester 93d 1. Photolysis i n Solution and i n t h e S o l i d S t a t e The t i t l e compound 93d undergoes a di-7r-methane rearrangement to give two regioisomeric dibenzosemibullvalene products 194 and 195 (Scheme 64) upon acetone-sensitized i r r a d i a t i o n i n s o l u t i o n . The two photoproducts, 194 and 195, are characterized by a n a l y t i c a l and spectroscopic methods, p a r t i c u l a r l y by the NMR spectra i n which the predominant photoproduct 194 shows a c h a r a c t e r i s t i c resonance at 6 = 4.40 ppm corresponding to the cyclopropyl proton. In contrast, the b e n z y l i c methine proton of the regioisomer 195 appears at 6 = 5.13 ppm. These assignments are i n agreement with the t y p i c a l chemical s h i f t s f o r 51 52 s i m i l a r dibenzosemibullvalene compounds. ' Scheme 64 Photorearrangements of 9-Chloromethyl Dibenzobarrelene 93d. 174 -I n c o n t r a s t t o t h e p h o t o l y s i s i n a c e t o n e ( t r i p l e t ) , i r r a d i a t i o n s i n b e n z e n e , a c e t o n i t r i l e , c a r b o n t e t r a c h l o r i d e , c h l o r o f o r m a n d i n t h e s o l i d s t a t e a f f o r d two a d d i t i o n a l m i n o r p h o t o p r o d u c t s w h i c h w e r e c h a r a c t e r i z e d a s t h e d i b e n z o p e n t a l e n e d e r i v a t i v e s 196 a n d 1 9 7 ( S c h e m e 6 4 ) . P r o d u c t s 1 9 6 a n d 197 w e r e i s o l a t e d f r o m a p r e p a r a t i v e p h o t o l y s i s i n c h l o r o f o r m b y c o l u m n c h r o m a t o g r a p h y o n s i l i c a g e l a n d b y f r a c t i o n a l c r y s t a l l i z a t i o n o f e a c h c o m p o u n d . A s t h e s p e c t r o s c o p i c d a t a f o r t h e s e m i n o r p h o t o p r o d u c t s w e r e n o t s u f f i c i e n t l y i n f o r m a t i v e t o a l l o w f o r u n a m b i g u o u s s t r u c t u r a l a s s i g n m e n t s , t h e i r s t r u c t u r e s w e r e e s t a b l i s h e d b y X - r a y c r y s t a l l o g r a p h i c s t u d i e s , w h i c h d e m o n s t r a t e d t h a t t h e two c o m p o u n d s h a v e t h e n o v e l , e x o - m e t h y l e n e , p e n t a l e n e - l i k e s t r u c t u r e s 196 a n d 1 9 7 . T h e i r O R T E P d r a w i n g s a r e p r e s e n t e d i n F i g u r e s 39 a n d 4 0 , r e s p e c t i v e l y . F i g u r e 39 O R T E P D r a w i n g o f t h e M o l e c u l a r S t r u c t u r e o f P h o t o p r o d u c t 1 9 6 . 175 -F i g u r e 40 O R T E P D r a w i n g o f t h e M o l e c u l a r S t r u c t u r e o f P h o t o p r o d u c t 1 9 7 . 2 . P r o d u c t R a t i o A n a l y s i s T h e p r o d u c t r a t i o s f r o m t h e p h o t o l y s i s o f c o m p o u n d 9 3 d i n v a r i o u s s o l v e n t s a n d i n t h e c r y s t a l l i n e s t a t e a r e s u m m a r i z e d i n T a b l e 1 5 . T h e t r i p l e t s t a t e ( a c e t o n e - s e n s i t i z e d ) p h o t o c h e m i s t r y o f d i b e n z o b a r r e l e n e 9 3 d i s u n e x c e p t i o n a l . L i k e many o t h e r s i m i l a r c o m p o u n d s d i s c u s s e d i n t h i s t h e s i s , t h e d i - j r - m e t h a n e p h o t o r e a r r a n g e m e n t o f c o m p o u n d 9 3 d p r o c e e d s s m o o t h l y i n a c e t o n e l e a d i n g t o t h e n o r m a l p r o d u c t s 194 a n d 1 9 5 . T h e r e g i o s e l e c t i v i t y i n t h i s c a s e i s a l s o s i m i l a r t o t h a t o f t h e o t h e r c o m p o u n d s ; d i b e n z o s e m i b u l l v a l e n e d i e s t e r 194 i s f o r m e d a s t h e m a j o r p h o t o p r o d u c t . D i s c u s s i o n s o n t h e s o l u t i o n p h a s e 176 -r e g i o s e l e c t i v i t y o f s i m i l a r c o m p o u n d s h a v e b e e n p r e s e n t e d i n t h e p r e v i o u s p a r t o f t h e t h e s i s ( s e c t i o n I I I . A . ) a n d n e e d n o t b e r e p e a t e d h e r e . T a b l e 14 P r o d u c t R a t i o s f r o m P h o t o l y s i s o f 9 - C h l o r o m e t h y l D i b e n z o b a r r e l e n e 9 3 d i n D i f f e r e n t M e d i a . 3 R e a c t i o n M e d i u m 194 P r o d u c t R a t i o 195 196 197 A c e t o n e B e n z e n e A c e t o n i t r i l e C h l o r o f o r m C a r b o n T e t r a c h l o r i d e 4 16 16 7 68 1 3 3 2 18 0 1 1 2 1 0 t r a c e t r a c e 1 t r a c e a - C r y s t a l ^ - C r y s t a l 7 - C r y s t a l 3 2 1 . 5 A n a l y s i s b y G C ; t h e r a t i o s d e t e r m i n e d b y c a p i l l a r y GC p e a k a r e a s ( u n c o r r e c t e d f o r d e t e c t o r r e s p o n s e ) . E s t i m a t e d e r r o r ± 5%. - 177 -S i n c e n o t r a c e o f t h e two m i n o r p r o d u c t s 196 a n d 197 c o u l d b e d e t e c t e d i n a c e t o n e , i t i s c o n s i d e r e d t h a t t h e y a r e p r o b a b l y d e r i v e d f r o m s i n g l e t s t a t e r e a c t i o n . T h i s i s s u p p o r t e d b y f u r t h e r p h o t o -s e n s i t i z a t i o n s t u d i e s o f 9 3 d i n c h l o r o f o r m u s i n g x a n t h o n e (E-j; = 74 89 k c a l / m o l ) a s t h e t r i p l e t e n e r g y s e n s i t i z e r , i n w h i c h t h e f o r m a t i o n o f p r o d u c t s 196 a n d 197 was n o t o b s e r v e d by G C ( r a t i o 1 9 4 : 1 9 5 - 4 : 1 ) . S e c o n d l y , i t c a n b e n o t e d f r o m T a b l e 15 t h a t t h e p r o d u c t r a t i o s c h a n g e m o d e r a t e l y u p o n v a r y i n g t h e r e a c t i o n m e d i u m f r o m s o l u t i o n t o t h e c r y s t a l l i n e s t a t e . A l t h o u g h t h e d i - j r - m e t h a n e r e a r r a n g e m e n t p r o d u c t s 194 a n d 195 r e m a i n p r e d o m i n a n t i n t h e s o l i d s t a t e , t h e p r o p o r t i o n o f t h e s i n g l e t - d e r i v e d p h o t o p r o d u c t s 196 a n d 1 9 7 i n c r e a s e s n o t i c e a b l y . I n a d d i t i o n , we a l s o n o t e t h a t t h e r e g i o s e l e c t i v i t y i n t h e d i - 7 r - m e t h a n e r e a r r a n g e m e n t o f 9 3 d i n s o l u t i o n ( 1 9 4 : 1 9 5 = 4 : 1 ) i s d i f f e r e n t f r o m . t h a t i n t h e s o l i d s t a t e ( 1 9 4 : 1 9 5 = 1 : 1 ) . A f i n a l i n t e r e s t i n g p o i n t i s t h a t t h e t h r e e p o l y m o r p h i c c r y s t a l s , i . e . a - , /3- a n d 7 - m o d i f i c a t i o n s , h a v e q u i t e s i m i l a r p h o t o c h e m i c a l b e h a v i o r i n t h a t t h e y a r e a l l p h o t o c h e m i c a l l y r e a c t i v e a n d t h e r e s u l t i n g p h o t o p r o d u c t s a r e t h e same w i t h s l i g h t l y d i f f e r e n t r a t i o s . 3 . A P o s s i b l e M e c h a n i s m f o r t h e F o r m a t i o n o f e x o - M e t h y l e n e D I b e n z o p e n t a l e n e s 196 a n d 1 9 7 . A s m e n t i o n e d a b o v e , t h e f o r m a t i o n o f t h e u n u s u a l d i b e n z o p e n t a l e n e d e r i v a t i v e s 196 a n d 197 was c o n s i d e r e d t o b e d e r i v e d f r o m a n e x c i t e d s i n g l e t s t a t e r e a c t i o n . T o h e l p i n u n d e r s t a n d i n g t h e s p e c u l a t i o n o n t h e m e c h a n i s m o f t h e i r f o r m a t i o n , a b r i e f r e v i e w o f c u r r e n t l i t e r a t u r e o n t h e s i n g l e t s t a t e r e a c t i v i t y o f b a r r e l e n e c o m p o u n d s i s p r e s e n t e d b e l o w . - 178 -I n S c h e m e 12 ( p a g e 2 9 ) , i t was m e n t i o n e d t h a t d i r e c t i r r a d i a t i o n o f b a r r e l e n e ( 5 6 ) a n d b e n z o b a r r e l e n e ( 5 9 ) p r o d u c e s c y c l o o c t a t e t r a e n e ( C O T ) d e r i v a t i v e s v i a S]_. S i m i l a r l y , s i n g l e t r e a c t i o n o f d i b e n z o b a r r e l e n e ( 1 9 8 ) g i v e s d i b e n z o c y c l o o c t a t e t r a e n e ( 2 0 0 ) a s t h e m a j o r p h o t o p r o d u c t o n d i r e c t i r r a d i a t i o n ( S c h e m e 6 5 ) . ^ 4 I t i s g e n e r a l l y a g r e e d 4 ^ < ^ - ® 5 t j l a t t j j e m e c h a n i s m i n v o l v e s [27r+2w] c y c l o a d d i t i o n l e a d i n g t o t h e c a g e i n t e r m e d i a t e 1 9 9 ( n o t i s o l a t e d ) , a n d t h a t t h i s i s f o l l o w e d b y b o n d r e o r g a n i z a t i o n t o f o r m t h e C O T d e r i v a t i v e ( S c h e m e 6 5 ) . T h e [2+2] m e c h a n i s m was s u p p o r t e d b y a d e u t e r i u m l a b e l i n g e x p e r i m e n t i n t h e c a s e o f b e n z o b a r r e l e n e ( 2 0 1 ) ( S c h e m e 6 6 ) . Z i m m e r m a n et al.^®~> s h o w e d t h a t t h e l a b e l e d c o m p o u n d 2 0 1 g i v e s a C O T d e r i v a t i v e s w i t h t h e l a b e l i n g p a t t e r n s h o w n i n S c h e m e 6 6 ; t h e r e s u l t s a r e c o n s i s t e n t w i t h t h e [2K+2TT] c y c l o a d d i t i o n m e c h a n i s m . - 179 -201 202 2 0 3 • r e p r e s e n t s H l a b e l d e u t e r i u m e l s e w h e r e S c h e m e 66 P h o t o r e a r r a n g e m e n t o f L a b e l e d B e n z o b a r r e l e n e v i a S ^ . H o w e v e r , i t h a s b e e n d i s c o v e r e d r e c e n t l y t h a t c e r t a i n s u b s t i t u t e d d i b e n z o b a r r e l e n e c o m p o u n d s f o r m n o v e l COT p r o d u c t s t h r o u g h t h e i r s i n g l e t e x c i t e d s t a t e s v i a a n a l t e r n a t i v e m e c h a n i s m . S c h e f f e r , T r o t t e r a n d c o -w o r k e r s ^ ^ r e p o r t e d t h a t d i r e c t i r r a d i a t i o n o f 9 , 1 0 - d i m e t h y l d i b e n z o b a r r e l e n e d i e s t e r 2 0 4 i n s o l u t i o n y i e l d s t h e d i - 7 r - m e t h a n e p r o d u c t 2 0 5 a n d t h e d i b e n z o c y c l o o c t a t e t r a e n e d e r i v a t i v e 2 0 7 ( S c h e m e 6 7 ) . T h e s t r u c t u r e o f p h o t o p r o d u c t 2 0 7 was c o n f i r m e d b y a n X - r a y c r y s t a l l o g r a p h i c a n a l y s i s . T h e m o s t i n t e r e s t i n g f e a t u r e o f t h e C O T p r o d u c t 207 i s t h a t i t s f o r m a t i o n c o u l d n o t b e r a t i o n a l i z e d b y t h e c o n c e r t e d [27r+27r] m e c h a n i s m , a s b y t h i s m e c h a n i s m o n e w o u l d p r e d i c t t h a t t h e C O T d e r i v a t i v e 2 1 0 w i t h m i r r o r ( C s ) s y m m e t r y w o u l d b e f o r m e d ( S c h e m e 6 7 ) . T h e s e a u t h o r s a l s o f o u n d t h a t i n t h e s o l i d s t a t e p h o t o t r a n s f o r m a t i o n o f c o m p o u n d 2 0 4 , a n u n u s u a l p e n t a l e n e - l i k e p h o t o p r o d u c t 2 0 6 p r e d o m i n a t e d . B a s e d o n t h e s t r u c t u r e o f t h i s p r o d u c t , a n o n - c o n c e r t e d m e c h a n i s m was p r o p o s e d , w h i c h i n v o l v e s f o r m a t i o n o f t h e b i r a d i c a l i n t e r m e d i a t e 208 b y - 180 -t w o 1 , 2 - a r y l s h i f t s t o t h e two v i n y l c a r b o n a t o m s o f 2 0 4 a s s h o w n i n S c h e m e 6 7 . F r o m t h e b i r a d i c a l s p e c i e s 2 0 8 , i t w a s s u g g e s t e d t h a t t h e COT p r o d u c t 2 0 7 h a v i n g C 2 s y m m e t r y c o u l d b e f o r m e d b y f r a g m e n t a t i o n , a n d t h a t d o u b l e 1 , 2 - e s t e r m i g r a t i o n s t o t h e r a d i c a l s i t e s w o u l d g i v e t h e d i b e n z o p e n t a l e n e d e r i v a t i v e 2 0 6 w i t h t h e o b s e r v e d s t e r e o c h e m i s t r y . S c h e m e 67 P h o t o r e a r r a n g e m e n t s o f 9 , 1 0 - D i m e t h y l D i b e n z o b a r r e l e n e D i e s t e r 2 0 4 . 1 8 1 -F o l l o w i n g t h e a b o v e p u b l i c a t i o n , G e o r g e a n d c o - w o r k e r s r e -e x a m i n e d t h e s t r u c t u r e s o f t h e p h o t o p r o d u c t s f r o m t h e p h o t o l y s i s o f d i b e n z o b a r r e l e n e d e r i v a t i v e 2 1 1 , a n a n a l o g u e o f c o m p o u n d 2 0 4 . I n a n 108 e a r l i e r r e p o r t b y t h e s e a u t h o r s , a C O T p r o d u c t w i t h C s s y m m e t r y ( c o m p o u n d 2 1 5 ) was a s s i g n e d b a s e d o n Z i m m e r m a n ' s [27r+27r] m e c h a n i s m ( S c h e m e 6 8 ) . I n t h e i r r e i n v e s t i g a t i o n b y X - r a y d i f f r a c t i o n m e t h o d , G e o r g e e t a l . f o u n d t h a t i n f a c t t h e COT f o r m e d h a s t h e s t r u c t u r e w i t h C2 s y m m e t r y ( c o m p o u n d 2 1 3 ) . I n a d d i t i o n , c o m p o u n d 2 1 1 w a s a l s o f o u n d t o r e a r r a n g e t o a d i b e n z o p e n t a l e n e d e r i v a t i v e 2 1 4 ( S c h e m e 6 8 ) . T h e s e a d d i t i o n a l r e s u l t s a r e i n a g r e e m e n t w i t h t h e S c h e f f e r ' s m e c h a n i s m i n v o l v i n g 1 , 4 - b i r a d i c a l i n t e r m e d i a t e 2 1 2 . B 215 S c h e m e 68 P h o t o r e a r r a n g e m e n t o f D i b e n z o y l D i b e n z o b a r r e l e n e 2 1 1 . 182 -I n a f a s h i o n s i m i l a r t o t h e p r e v i o u s l y p r o p o s e d m e c h a n i s m , we s u g g e s t e d t h e f o l l o w i n g m e c h a n i s m f o r t h e f o r m a t i o n o f p h o t o p r o d u c t s 196 a n d 197 ( f r o m d i r e c t i r r a d i a t i o n i n s o l u t i o n a n d i n t h e s o l i d s t a t e ) i n S c h e m e 6 9 . I t i n v o l v e s t h e k e y r e a c t i o n i n t e r m e d i a t e , b i r a d i c a l 2 1 6 , w h i c h i s f o r m e d m o s t l i k e l y t h r o u g h a n o n - c o n c e r t e d 1 , 2 - a r y l s h i f t t o o p p o s i t e f a c e s o f t h e v i n y l c a r b o n a t o m s ( C 1 2 a n d C l l ) a s s h o w n b y t h e a r r o w s . H o m o l y s i s o f t h e C - C l b o n d o f 2 1 6 w o u l d f o r m m o n o - r a d i c a l 2 1 7 h a v i n g a n e x o - c y c l i c m e t h y l e n e g r o u p p l u s a c h l o r i n e a t o m . T h e m o n o r a d i c a l s p e c i e s 217 c o u l d r e c o m b i n e w i t h t h e c h l o r i d e a t o m t o p r o d u c e s t e r e o i s o m e r s 196 a n d 1 9 7 . T h e f o r m a t i o n o f e l i m i n a t i o n p r o d u c t s b y / 3 - s c i s s i o n o f a c a r b o n - c h l o r i n e b o n d o f a 1 , 4 - b i r a d i c a l c a n b e f o u n d 109 i n t h e w o r k o f W a g n e r et al. o n t h e N o r r i s h T y p e I I r e a c t i o n o f 5 -c h l o r o v a l e r o p h e n o n e a n d r e l a t e d c o m p o u n d s . A n a l t e r n a t i v e p o s s i b i l i t y i s t h e d i r e c t t r a n s f e r o f a c h l o r i n e a t o m f r o m t h e c h l o r o m e t h y l g r o u p o f o n e b i r a d i c a l 216 t o t h e s e c o n d a r y r a d i c a l s i t e o f a n o t h e r . S c h e m e 69 P r o p o s e d M e c h a n i s m f o r t h e F o r m a t i o n o f P r o d u c t 196 a n d 1 9 7 . - 183 -R e g a r d i n g w h e t h e r t h e f o r m a t i o n o f e p i m e r s 1 9 6 a n d 197 f r o m b i r a d i c a l 2 1 6 i s i n t r a - o r i n t e r m o l e c u l a r i n n a t u r e , i t s e e m s l i k e l y t h a t t h e i n t r a m o l e c u l a r t r a n s f e r o f a c h l o r i n e a t o m i s n o t p o s s i b l e o n s t e r i c g r o u n d s . M o l e c u l a r m o d e l s i n d i c a t e t h a t t h e b i r a d i c a l i n t e r m e d i a t e 2 1 6 i s r i g i d a n d n e a r l y p l a n a r , a n d t h a t c h l o r i n e a t o m o f t h e c h l o r o m e t h y l g r o u p c a n n o t a p p r o a c h t o w i t h i n b o n d i n g d i s t a n c e o f t h e r a d i c a l s i t e . B u t d i r e c t r e c o m b i n a t i o n o f a n i n i t i a l l y f o r m e d r a d i c a l p a i r w i t h i n a s o l v e n t c a g e i s c o n s i d e r e d t o b e p o s s i b l e i n t h e s o l u t i o n 109 p h a s e . S u c h a p r o c e s s w a s s u g g e s t e d b y W a g n e r et al. i n t h e i r N o r r i s h t y p e I I w o r k . I n c o n t r a s t , a n i n t e r m o l e c u l a r c h l o r i n e a t o m t r a n s f e r s e e m s m o r e l i k e l y i n t h e s o l i d s t a t e , a s t h e i n t r a m o l e c u l a r r e c o m b i n a t i o n o f t h e r a d i c a l p a i r w o u l d n o t a p p e a r t o b e f e a s i b l e i n t h e c r y s t a l l i n e m e d i u m . E x a m i n a t i o n o f t h e X - r a y c r y s t a l s t r u c t u r e o f c o m p o u n d 9 3 d ( / 3 - f o r m ) r e v e a l s t h a t t h e r e e x i s t s a m o d e r a t e l y s h o r t i n t e r m o l e c u l a r c o n t a c t o f • 82 4 . 2 8 A ( s u m o f t h e v a n d e r W a a l s r a d i i f o r C a n d C I i s 3 . 5 5 A ) b e t w e e n t h e c h l o r i n e a t o m o f o n e m o l e c u l e a n d t h e b r i d g e h e a d c a r b o n a t o m C ( 1 0 ) o f a n e i g h b o r i n g m o l e c u l e . A c r y s t a l p a c k i n g d i a g r a m i s s h o w n i n F i g u r e 4 1 . I t c a n b e n o t e d t h a t i n t h e p r o p o s e d m e c h a n i s m ( S c h e m e 6 9 ) , i t i s C ( 1 0 ) t h a t b e c o m e s t h e c h l o r i n e - b e a r i n g c a r b o n a t o m o f p h o t o p r o d u c t s 1 9 6 a n d 1 9 7 . S u c h a p r o c e s s o f i n t e r m o l e c u l a r s o l i d s t a t e c h l o r i n e a t o m t r a n s f e r w a s f i r s t s u g g e s t e d b y D e c o r e t et a l . t o a c c o u n t f o r t h e c r y s t a l l i n e p h a s e p h o t o t r a n s f o r m a t i o n o f 2 , 4 , 6 , 6 - t e t r a c h l o r o c y c l o h e x a d i e n e d e r i v a t i v e 218 t o i t s c r o s s - c o n j u g a t e d 2 , 4 , 4 , 6 - t e t r a c h l o r o i s o m e r 219 ( S c h e m e 7 0 ) . I n t h i s c a s e , i t was s h o w n b y X - r a y c r y s t a l l o g r a p h i c a n a l y s i s t h a t t h e - 184 i n t e r m o l e c u l a r C ( 6 ) - C l • - • C ( 4 ) c o n t a c t i s 4 . 6 A . T h e e x i s t e n c e o f 4 . 2 8 A i n t e r m o l e c u l a r C - - - C l c o n t a c t i n c r y s t a l l i n e 9 3 d ( / 3 - m o d i f i c a t i o n ) i s p e r h a p s o n e r e a s o n f o r t h e f o r m a t i o n o f h i g h e r y i e l d s o f s t e r e o i s o m e r s 1 9 6 a n d 1 9 7 i n t h e c r y s t a l l i n e m e d i u m c o m p a r e d t o t h a t I n s o l u t i o n . F i g u r e 4 1 C r y s t a l P a c k i n g D i a g r a m o f C o m p o u n d 9 3 d ( / 3 - f o r m ) . S c h e m e 70 P h o t o t r a n s f o r m a t i o n o f T e t r a c h l o r o c y c l o h e x a d i e n o n e 2 1 8 . 185 -B . S o l i d S t a t e P h o t o c h r o m i s m o f 9 - C h l o r o m e t h y l D i b e n z o b a r r e l e n e 9 3 d P h o t o c h r o m i s m i s d e f i n e d ^ ^ ^ a s t h e p h e n o m e n o n w h e r e b y a s u b s t a n c e u n d e r g o e s a c o l o r c h a n g e u p o n a b s o r p t i o n o f l i g h t . B y d e f i n i t i o n , t h e p r o c e s s s h o u l d b e r e v e r s i b l e , e i t h e r t h e r m a l l y o r p h o t o c h e m i c a l l y . M a n y p h o t o c h r o m i c s y s t e m s a r e k n o w n a n d s e v e r a l h a v e b e e n 3 s t z 112 t h o r o u g h l y s t u d i e d i n s o l u t i o n a n d i n t h e s o l i d s t a t e a s w e l l . ' ' ' O n e o f t h e e a r l i e s t e x a m p l e s o f s o l i d s t a t e p h o t o c h r o m i s m i s t h a t o f t h e t e t r a c h l o r o d i h y d r o n a p h t h a l e n - l - o n e d e r i v a t i v e (220) ( S c h e m e 7 1 ) . I t i s o f p a r t i c u l a r i n t e r e s t i n r e l a t i o n t o t h e p r e s e n t w o r k o n t h e p h o t o c h r o m i s m o f c o m p o u n d 9 3 d . T h e p h o t o c h r o m i s m o f c o m p o u n d 220 i n t h e s o l i d s t a t e w a s f i r s t 113 i n v e s t i g a t e d b y M a r c k w a l d i n 1 8 9 9 . C o l o r l e s s c r y s t a l s o f t h i s c o m p o u n d b e c o m e d e e p b l u e u p o n U V - i r r a d i a t i o n , a n d w h e n p l a c e d i n t h e d a r k o r u p o n h e a t i n g t h e y r e v e r t t o c o l o r l e s s . T h i s p h o t o c h r o m i s m a l s o o c c u r s i n s o l u t i o n a n d h a s b e e n s t u d i e d f o r many y e a r s . I t was o r i g i n a l l y t h o u g h t b y S c h e i b l e a n d F e i c h t m a y r ' ' " ' ' " 4 t o b e t h e r e s u l t o f c a r b o n - c h l o r i n e b o n d h o m o l y s i s t o g i v e a c h l o r i n e a t o m a n d t h e c o n j u g a t e d a l l y l r a d i c a l 221a. I n s u p p o r t o f t h i s i d e a , c r y s t a l s o f 220 a r e f o u n d t o g i v e r i s e t o a n E S R s i g n a l w h e n p h o t o l y z e d . H o w e v e r , l a t e r e x p e r i m e n t s b y Z w e e g e r s et al.^^ s h o w e d t h a t t h e d e c a y r a t e s o f t h e c o l o r e d s p e c i e s ( a b s o r p t i o n b a n d a t ca. 530 nm) a n d t h e s p e c i e s r e s p o n s i b l e f o r t h e E S R s i g n a l a r e d i f f e r e n t . T h e s e a u t h o r s p r o p o s e d t h a t t h e c a r b e n i u m i o n 221b i s t h e s p e c i e s r e s p o n s i b l e f o r t h e p h o t o c h r o m i s m . 186 0 Cl 221b Scheme 71 P h o t o c h r o m i s m o f T e t r a c h l o r o d i h y d r o n a p h t h a l e n - l - o n e (220). N o t e w o r t h y o f t h e p h o t o c h r o m i c b e h a v i o r o f c r y s t a l s o f 220 i s t h a t t h i s c o m p o u n d i s t r i m o r p h i c ( s p a c e g r o u p s P n m a , P 2 T / C , a n d P n 2 i a ) a n d t h a t o n l y t h e o n e o f t h e s e c r y s t a l m o d i f i c a t i o n s ( P n m a ) i s p h o t o c h r o m i c i n t h e s o l i d . B y s t u d y i n g t h e c r y s t a l s t r u c t u r e o f e a c h o f t h e c r y s t a l m o d i f i c a t i o n s , Z w e e g e r a n d c o - w o r k e r s i X ^ s u g g e s t e d t h a t t h e r e v e r s e p r o c e s s ( d e c o l o r i z a t i o n ) b y r e c o m b i n a t i o n o f t h e i o n p a i r ( C l " a n d t h e c a r b e n i u m i o n ) i n t h e p h o t o c h r o m i c c r y s t a l s i s r e t a r d e d b y a s h o r t ( 2 . 9 7 A ) i n t e r m o l e c u l a r C = 0 - - - C 1 c o n t a c t ( F i g u r e 4 2 ) . T h i s c o n t a c t , w h i c h i s l e s s t h a n t h e sum ( 3 . 3 2 A ) o f t h e V a n d e r W a a l s r a d i i f o r C l a n d 0 , ^ 2 ^ s a b s e n t i n t h e n o n - p h o t o c h r o m i c m o d i f i c a t i o n s o f 220. T h e r e f o r e , t h e c o l o r e d s p e c i e s m i g h t b e f o r m e d , b u t b e t o o s h o r t - l i v e d t o b e d e t e c t e d i n t h e s e c a s e s . - 187 -CI 0. CI \"o ' CI , C k . CI / CI ^ Y - c i ci 2.97 220 F i g u r e 42 I n t e r m o l e c u l a r C o n t a c t i n C r y s t a l S t r u c t u r e o f 220 1 . G e n e r a l O b s e r v a t i o n s o n t h e P h o t o c h r o m i s m o f C o m p o u n d 9 3 d . C o m p o u n d 9 3 d was f i r s t i r r a d i a t e d i n s o l u t i o n a n d f o u n d t o b e n o n -p h o t o c h r o m i c . A s m e n t i o n e d p r e v i o u s l y , c o m p o u n d 9 3 d i s o b t a i n e d i n t h r e e d i f f e r e n t c r y s t a l l i n e m o d i f i c a t i o n s . S i n g l e c r y s t a l s o r p o w d e r e d s a m p l e s o f e a c h o f t h e p o l y m o r p h s w e r e i r r a d i a t e d b y e i t h e r a UV l a m p ( P y r e x f i l t e r , A > 2 9 0 nm) o r a n i t r o g e n l a s e r (A = 337 nm) f o r p e r i o d s r a n g i n g f r o m 30 s t o 5 m i n . I t was f o u n d t h a t t w o o f t h e c r y s t a l m o d i f i c a t i o n s , t h e / S - f o r m a n d t h e 7 - f o r m , a r e p h o t o c h r o m i c d i s p l a y i n g d i f f e r e n t c o l o r s ; h o w e v e r , t h e a - t y p e c r y s t a l s a r e n o t p h o t o c h r o m i c . When t h e / 3 - t y p e c r y s t a l s o f 9 3 d a r e i r r a d i a t e d , t h e c o l o r l e s s c r y s t a l s t u r n t o a d a r k b l u e - p u r p l e c o l o r . T h e i n t e n s i t y o f t h e c o l o r i s p r o p o r t i o n a l t o t h e t i m e o f t h e i r r a d i a t i o n ( w i t h i n 5 m i n ) . T h e p h o t o l y z e d c r y s t a l s l o s e t h e i r c o l o r a t i o n i n a f e w h o u r s i f t h e c r y s t a l - 188 s t a n d s i n t h e d a r k a t r o o m t e m p e r a t u r e . H e a t i n g t h e c r y s t a l s c a n r e m o v e t h e c o l o r m u c h f a s t e r . A l s o , t h e c o l o r d i s a p p e a r s i m m e d i a t e l y a f t e r t h e p h o t o l y z e d c r y s t a l s a r e d i s s o l v e d i n a s u i t a b l e s o l v e n t . E x p e r i m e n t s s h o w e d t h a t t h i s i s a r e v e r s i b l e p r o c e s s w h i c h c a n b e r e p e a t e d many t i m e s w i t h o u t d a m a g i n g t h e c r y s t a l s . N o p h o t o p r o d u c t w e r e d e t e c t e d b y GC o r FTIR. H o w e v e r , w h e n t h e i r r a d i a t i o n i s p r o l o n g e d f o r 2 h , t h e c r y s t a l l i n e s a m p l e s b e c o m e p e r m a n e n t l y y e l l o w i n c o l o r a c c o m p a n i e d b y p h o t o r e a c t i o n s . T h e s o l i d s t a t e U V - V I S a b s o r p t i o n s p e c t r u m f o r t h e c o l o r e d s p e c i e s ( / 3 - f o r m ) i n K B r i s s h o w n i n F i g u r e 4 3 . I t d i s p l a y s a w e a k a b s o r p t i o n b a n d a t A = 5 7 7 nm w h i c h i s a b s e n t b e f o r e i r r a d i a t i o n a n d c o u l d n o t b e s e e n w h e n t h e b l u e - p u r p l e c o l o r f a d e s a f t e r h e a t i n g o f t h e K B r p e l l e t . P-E LAHB0A 4B ID 826'CYC/Tjn 881/ 8.88 SCAM (C)=H0E A:SLT 1RSP 3SP0 128 CrCI 881 W a v e l e n g t h (nm) F i g u r e 43 U V - V I S A b s o r p t i o n S p e c t r u m o f t h e B l u e - P u r p l e S p e c i e s F o r m e d i n t h e P h o t o c h r o m i c p " - T y p e C r y s t a l s o f 9 3 d . 189 T h e p h o t o c h r o m i c b e h a v i o r o f t h e 7 - t y p e c r y s t a l m o d i f i c a t i o n i s s l i g h t l y d i f f e r e n t f r o m t h a t o f t h e / 3 - t y p e . U p o n i r r a d i a t i o n f o r a f e w m i n u t e s , t h e c o l o r l e s s c r y s t a l s ( 7 - t y p e ) b e c o m e r e d - v i o l e t i n c o l o r . A l s o , i t i s o b s e r v e d t h a t t h e r e s u l t i n g c o l o r f a d e s m u c h f a s t e r t o c o m p l e t e l y c o l o r l e s s ( w i t h i n c a . 5 m i n ) , c o m p a r e d t o t h a t o f t h e / 3 - t y p e c r y s t a l s ( s e v e r a l h o u r s ) . A n o t h e r i n t e r e s t i n g f e a t u r e o f t h e p h o t o c h r o m i s m o f t h e 7 - c r y s t a l s i s t h a t t h e y a r e t h e r m a l l y u n s t a b l e a t h i g h t e m p e r a t u r e . W h e n h e a t e d t o 1 3 0 - 1 4 0 ° , t h e t r a n s p a r e n t c r y s t a l s ( m . p . 1 6 8 - 1 7 0 ° ) t u r n o p a q u e . T h e s e o p a q u e c r y s t a l s h a v e e x a c t l y t h e same p h o t o c h r o m i c b e h a v i o r ( b e c o m e d a r k b l u e - p u r p l e u p o n i r r a d i a t i o n ) a s t h o s e o f t h e p ' - t y p e c r y s t a l m o d i f i c a t i o n . T h e F T I R s p e c t r u m o f t h e o p a q u e c r y s t a l s i n d i c a t e s t h a t t h e 7 - t y p e c r y s t a l s h a v e b e e n c o n v e r t e d t o t h e p-form. T h i s p h e n o m e n o n i s t h o u g h t t o b e t h e r e s u l t o f a p h a s e t r a n s i t i o n i n t h e c r y s t a l l i n e s t a t e . H o w e v e r , d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y ( D S C ) m e a s u r e m e n t s d i d n o t s h o w a p h a s e t r a n s i t i o n i n t h e t e m p e r a t u r e r a n g e 3 5 ° - 2 0 0 ° C . T h i s r e s u l t i s p u z z l i n g b e c a u s e a p h a s e t r a n s i t i o n w i t h o u t h e a t e x c h a n g e w o u l d s e e m u n l i k e l y . T h e p o s s i b i l i t y t h a t l o s s o f s o l v e n t m o l e c u l e s t r a p p e d i n t h e c r y s t a l s c a u s e s t h e c h a n g e s i n c r y s t a l t e x t u r e h a s b e e n e l i m i n a t e d , s i n c e t h e m a s s o f t h e s a m p l e a f t e r t h e DSC m e a s u r e m e n t r e m a i n s u n c h a n g e d . 2 . S p e c u l a t i o n o n t h e N a t u r e o f t h e C o l o r e d S p e c i e s . T h e q u e s t i o n i s , w h a t i s r e s p o n s i b l e f o r t h e p h o t o c h r o m i c b e h a v i o r o f c o m p o u n d 9 3 d ? F i r s t , i t i s c l e a r t h a t t h i s p h o t o c h r o m i s m i s c a u s e d b y t h e f o r m a t i o n o f a c e r t a i n s p e c i e s p h o t o i n d u c e d i n t h e c r y s t a l l i n e 190 -s t a t e . a s 93d i s n o t p h o t o c h r o m i c i n s o l u t i o n . S e c o n d l y , t h e p o s s i b i l i t y t h a t a n i m p u r i t y p r e s e n t i n t h e c r y s t a l s m i g h t b e r e s p o n s i b l e f o r t h e p h o t o c h r o m i s m i s u n l i k e l y . T h i s i s b e c a u s e , a s m e n t i o n e d a b o v e , t h e a-t y p e c r y s t a l s a r e n o n - p h o t o c h r o m i c , w h i l e t h e /3- a n d 7- t y p e c r y s t a l s a r e , a n d t h e s e p o l y m o r p h i c m o d i f i c a t i o n s c a n b e i n t e r c o n v e r t e d b y s u i t a b l e r e c r y s t a l l i z a t i o n c o n d i t i o n s . I n a d d i t i o n , t h e / 9 - t y p e c r y s t a l s ( p h o t o c h r o m i c ) w e r e u s e d t o p r e p a r e t h i n p o l y m e r f i l m s ; i r r a d i a t i o n o f t h e f i l m s d i d n o t c a u s e p h o t o c h r o m i s m . T h e i m p o r t a n t o b s e r v a t i o n t h a t t h e t r i m o r p h s ( a - , /9- a n d 7 - f o r m s ) e x h i b i t d i f f e r e n t p h o t o c h r o m i c b e h a v i o r s t r o n g l y s u g g e s t s t h a t c r y s t a l p a c k i n g i s a k e y f a c t o r i n d e t e r m i n i n g t h i s p h o t o c h r o m i s m . I n a n a t t e m p t t o i d e n t i f y t h e b l u e - p u r p l e s p e c i e s f o r m e d i n t h e p h o t o c h r o m i c c r y s t a l s ( / 9 - t y p e ) , we w e r e s u c c e s s f u l i n d e t e c t i n g a n E S R s i g n a l w h i c h may b e l o n g t o t h e c o l o r e d s p e c i e s . E S R s p e c t r a ^ o f t h e i r r a d i a t e d c r y s t a l l i n e c o m p o u n d 93d ( / 3 - t y p e c r y s t a l s ) a r e s h o w n i n F i g u r e 4 4 . T h e g - v a l u e d e t e r m i n e d ( g — 1 . 9 9 1 5 ) i n d i c a t e s t h a t t h e r a d i c a l s p e c i e s i s o r g a n i c i n n a t u r e . I t i s a l s o o b s e r v e d t h a t t h e i n t e n s i t y o f t h i s E S R s i g n a l d e c a y s w i t h t i m e a n d e v e n t u a l l y i s a b s e n t w h e n t h e b l u e - p u r p l e c o l o r d i s a p p e a r s . t ESR measurements were kindly provided by Dr. F. G. Herring in the UBC Chemistry Department. 191 F i g u r e 45 - E S R S p e c t r a o f t h e B l u e - P u r p l e S p e c i e s F o r m e d i n t h e P h o t o c h r o m i c / ? - T y p e C r y s t a l s o f C o m p o u n d 93d. ( a ) c r y s t a l l i n e s a m p l e a t R T . ( b ) p o w d e r s a m p l e a t 77K. T h e i n f o r m a t i o n o b t a i n e d h e r e s e e m s t o s u g g e s t t h a t a r a d i c a l s p e c i e s i s r e s p o n s i b l e f o r t h e p h o t o c h r o m i c b e h a v i o r o f c r y s t a l l i n e c o m p o u n d 93d (/9 - form), a s s u m i n g t h a t t h e r a d i c a l s p e c i e s i s t h e s a m e i n t e r m e d i a t e a s t h a t o b s e r v e d i n t h e U V a b s o r p t i o n s p e c t r u m a t 577 n m . O t h e r d i b e n z o b a r r e l e n e c o m p o u n d s i n v e s t i g a t e d i n o u r l a b o r a t o r y 118 w e r e s h o w n t o e x h i b i t s i m i l a r p h o t o c h r o m i c b e h a v i o r . I n o n e i n s t a n c e , c r y s t a l s o f c o m p o u n d 222 ( F i g u r e 45) t u r n p u r p l e u p o n U V - i r r a d i a t i o n a n d t h e c o l o r f a d e s w i t h t i m e i n t h e d a r k . E S R s p e c t r u m o f t h e i r r a d i a t e d - 192 -c r y s t a l s h o w s a s i g n a l a t a g - v a l u e o f 2 . 0 0 4 3 . S i m i l a r t o 9 3 d , c o m p o u n d 2 2 2 i s n o t p h o t o c h r o m i c i n s o l u t i o n . F i g u r e 46 S t r u c t u r e s o f O t h e r P h o t o c h r o m i c D i b e n z o b a r r e l e n e C o m p o u n d s . R e g a r d i n g t h e n a t u r e o f t h e r a d i c a l s p e c i e s i n v o l v e d i n t h e p h o t o c h r o m i s m , o n e p o s s i b i l i t y i s t h a t f o r m a t i o n o f t h e b i r a d i c a l i n t e r m e d i a t e s p e c i e s f r o m t h e t r i p l e t d i - 7 r - m e t h a n e r e a r r a n g e m e n t o r f r o m t h e u n u s u a l s i n g l e t r e a r r a n g e m e n t ( S c h e m e 69) o f c o m p o u n d 9 3 d m i g h t b e r e s p o n s i b l e f o r t h e p h o t o c h r o m i s m . B u t , we s p e c u l a t e t h a t t h e s e b i r a d i c a l s p e c i e s w o u l d n o t a b s o r b i n t h e v i s i b l e r e g i o n ( c a . 570 nm) t o e x h i b i t t h e d a r k b l u e - p u r p l e c o l o r . S e c o n d l y , i n a n a l o g y t o t h e p h o t o c h r o m i s m o f c o m p o u n d 2 2 0 ( S c h e m e 71), i t c a n b e s p e c u l a t e d t h a t h o m o l y t i c o r h e t e r o l y t i c c l e a v a g e o f t h e C - C l b o n d o f c o m p o u n d 9 3 d w o u l d r e s u l t i n a r a d i c a l o r a p o s i t i v e c h a r g e p r e s e n t a t t h e m e t h y l e n e c a r b o n a t o m , w h e t h e r o r n o t , h o w e v e r , t h e r a d i c a l o r i o n s p e c i e s w o u l d a b s o r b a t c a . 5 7 0 nm i s y e t u n k n o w n . T h e f a c t i s t h a t t h e d i b e n z o b a r r e l e n e 119 d e r i v a t i v e 2 2 3 ( F i g u r e 4 5 ) , w h i c h d o e s n o t c o n t a i n a c h l o r i n e s u b s t i t u e n t , i s a l s o p h o t o c h r o m i c i n t h e s o l i d s t a t e ; t h e r e s u l t i n g 222 223 E C O 2 C H 3 - 193 -c o l o r a n d t h e E S R s p e c t r a o f t h e i r r a d i a t e d c r y s t a l s a r e v e r y s i m i l a r t o t h o s e o f c o m p o u n d 2 2 2 . I t s e e m s t h a t a m e c h a n i s m i n v o l v i n g t h e p r e s e n c e o f a c h l o r i n e a t o m i n t h e p h o t o c h r o m i s m may n o t b e n e c e s s a r y . O n t h e o t h e r h a n d , i t i s a l s o p o s s i b l e t h a t d i f f e r e n t p h e n o m e n a a r e r e s p o n s i b l e f o r t h e p h o t o c h r o m i s m o f t h e s e c o m p o u n d s . T h u s , t h e r e s u l t s f r o m a l l o f t h e a b o v e o b s e r v a t i o n s a r e n o t c o n c l u s i v e . T h e p r o f i l e s e e m s t o b e t h a t a c e r t a i n r a d i c a l s p e c i e s , w h i c h i s a s s o c i a t e d w i t h t h e c r y s t a l l a t t i c e , i s i n v o l v e d i n t h i s k i n d o f s o l i d s t a t e p h o t o c h r o m i s m ; w h e t h e r t h e p h o t o c h r o m i s m o c c u r s t h r o u g h a u n i m o l e c u l a r o r b i m o l e c u l a r p r o c e s s i s y e t u n c l e a r . E x a m i n a t i o n o f t h e c r y s t a l p a c k i n g a r r a n g e m e n t o f c o m p o u n d 9 3 d ( / 3 - t y p e , F i g u r e 4 2 ) p r o v i d e s n o s p e c i f i c i n t r a - o r i n t e r m o l e c u l a r c o n t a c t s w h i c h c o u l d b e r e l a t e d t o t h e o b s e r v e d p h o t o c h r o m i s m . F u r t h e r X - r a y c r y s t a l l o g r a p h i c a n a l y s i s o f t h e a - a n d 7 - m o d i f i c a t i o n s o f c o m p o u n d 9 3 d i s r e q u i r e d ( c r y s t a l s t r u c t u r e s o f t h e a - m o d i f i c a t i o n a n d t h e 7 - m o d i f i c a t i o n h a v e n o t b e e n s o l v e d o w i n g t o d i s o r d e r o f t h e c r y s t a l s ) . B y c o m p a r i s o n o f t h e i r c r y s t a l s t r u c t u r e s , i t m i g h t b e p o s s i b l e t o u n d e r s t a n d t h e d i f f e r e n t p h o t o c h r o m i c b e h a v i o r o f t h e p o l y m o r p h s o f c o m p o u n d 9 3 d . - 194 -EXPERIMENTAL - 195 -I. G e n e r a l M e l t i n g P o i n t s ( m . p . ) A l l m e l t i n g p o i n t s w e r e m e a s u r e d o n a F i s h e r - J o h n s h o t s t a g e m e l t i n g p o i n t a p p a r a t u s a n d a r e u n c o r r e c t e d . I n f r a r e d S p e c t r a ( I R ) I n f r a r e d s p e c t r a w e r e r e c o r d e d o n a P e r k i n - E l m e r 1 7 1 0 F o u r i e r t r a n s f o r m i n f r a r e d s p e c t r o p h o t o m e t e r i n e i t h e r o f t h e two w a y s : 1 ) a s t h i n f i l m s b e t w e e n two s o d i u m c h l o r i d e p l a t e s f o r l i q u i d o r o i l y s a m p l e s , 2 ) a s K B r p e l l e t s p r e p a r e d b y g r i n d i n g p o t a s s i u m b r o m i d e t o g e t h e r w i t h a s a m p l e ( 1 - 3 mg o f t h e s a m p l e i n 1 0 0 - 1 5 0 mg o f K B r ) a n d p r e s s i n g t h e p o w d e r e d m i x t u r e i n a P e r k i n - E l m e r 1 8 6 - 0 0 0 2 e v a c u a t e d d i e w i t h C a r v e r M o d e l B l a b o r a t o r y p r e s s a t 2 0 , 0 0 0 p o u n d s p e r s q u a r e i n c h ( p s i ) . A b s o r p t i o n m a x i m a ( " m a x ) a r e r e p o r t e d i n r e c i p r o c a l c e n t i m e t e r ( c m " 1 ) . N u c l e a r M a g n e t i c R e s o n a n c e S p e c t r a (NMR) P r o t o n n u c l e a r m a g n e t i c r e s o n a n c e (^H NMR) s p e c t r a w e r e r e c o r d e d i n d e u t e r o c h l o r o f o r m o n B r u k e r A C - 2 0 0 ( 2 0 0 M H z ) , V a r i a n X L - 3 0 0 ( 3 0 0 MHz) a n d B r u k e r W P - 4 0 0 ( 4 0 0 M H z ) s p e c t r o m e t e r s a t a m b i e n t t e m p e r a t u r e u n l e s s s p e c i f i e d o t h e r w i s e . S i g n a l p o s i t i o n s a r e r e p o r t e d a s c h e m i c a l s h i f t (6) i n p a r t s p e r m i l l i o n (ppm) w i t h t e t r a m e t h y l s i l a n e ( T M S ) a s a n i n t e r n a l r e f e r e n c e . M u l t i p l i c i t y o f t h e s i g n a l s , n u m b e r o f p r o t o n s , c o u p l i n g c o n s t a n t ( J ) i n Hz a n d a s s i g n m e n t a r e g i v e n i n p a r e n t h e s e s f o l l o w i n g t h e - 196 -chemical shifts. The multiplicities of the signals are abbreviated as follows: s = singlet, d = doublet, dd = doublet of doublets, t = tr i p l e t , q = quartet and m = multiplet. 13 Carbon nuclear magnetic resonance spectra ( C NMR) were recorded either at 75.4 MHz on a Varian XL-300 spectrometer and/or at 50.3 MHz on a Bruker AC-200 spectrometer in deuterochloroform which was also used as the internal reference at ambient temperature. Chemical shifts (6) are 13 1 reported under broad band proton decoupling C-{ H) in ppm and are followed by their assignments which were determined by the attached proton test (APT) experiment. Mass Spectra (MS) Low and high resolution mass spectra were determined on a Kratos MS-50 mass spectrometer. Gas chromatography-mass spectral analyses (GC-MS) were performed on a Kratos MS-80PRF spectrometer coupled with a Carlo-Erba gas chromatograph. Ultraviolet Spectra (UV) Ultraviolet spectra were recorded on a Perkin-Elmer Lambda-4B UV/Vis spectrophotometer. Wavelength (A) in nanometer (nm) and extinction coefficient (e) of each absorption maxima are given. Spectral grade solvents available from BDH were used without any further purification. Solid state UV spectra were measured by using the KBr pellet, which was prepared in the same way as that described in the FTIR - 197 -m e a s u r e m e n t . A b l a n k K B r p e l l e t w a s u s e d a s r e f e r e n c e , a n d t h e s a m p l e K B r p e l l e t c o n t a i n e d 2 0 - 5 0 mg o f t h e s u b s t r a t e i n 1 0 0 - 1 5 0 mg o f K B r . E l e m e n t a l A n a l y s e s ( E A ) A l l e l e m e n t a l a n a l y s e s w e r e p e r f o r m e d b y t h e d e p a r t m e n t a l m i c r o a n a l y s t , M r . P . B o r d a . O p t i c a l R o t a t i o n s ( a ) O p t i c a l r o t a t i o n s ( a ) w e r e m e a s u r e d o n a P e r k i n - E l m e r 141 p o l a r i m e t e r o p e r a t e d a t t h e s o d i u m D l i n e ( 5 8 9 nm) i n m o s t c a s e s u n l e s s 20 o t h e r w i s e s p e c i f i e d . T h e i n s t r u m e n t w a s c a l i b r a t e d b o t h t o [ a ] n = 0 ° 20 w i t h a n a l y t i c a l l y p u r e c h l o r o f o r m a n d t o tA]D = - 5 0 ° ( c = 5 ) w i t h ( 1 R , 2 S , 5 R ) - ( - ) - m e n t h o l i n e t h a n o l . T h e t e m p e r a t u r e a t w h i c h t h e o p t i c a l r o t a t i o n was m e a s u r e d w a s a l s o r e c o r d e d . S p e c i f i c r o t a t i o n , [GOD*"' W A S c a l c u l a t e d b y t h e f o l l o w i n g e q u a t i o n : M D = X 1 0 0 1 x c W h e r e t = t h e t e m p e r a t u r e a t w h i c h t h e o p t i c a l r o t a t i o n w a s m e a s u r e d . D = t h e s o d i u m D l i n e a t 5 8 9 n m . a = t h e r e c o r d e d o p t i c a l r o t a t i o n i n d e g r e e s . 1 = t h e p a t h l e n g t h i n d e c i m e t e r s . c = t h e c o n c e n t r a t i o n o f t h e s a m p l e s o l u t i o n i n m i l l i g r a m s p e r 10 m L . 198 Chromatography Gas liquid chromatography (GLC or GC) analyses were performed on a Hewlett Packard 5890A gas chromatograph f i t t e d with a flame ionization detector, and the instrument was equipped with a Hewlett Packard 3392A integrator. A l l the chromatographic analyses were carried out on one of the following fused s i l i c a capillary columns: 1) a 15m x 0.25mm DB-1 column from J&W Scientific Inc., 2) a 15m x 0.25mm DB-17 column from J&W Scientific Inc., 3) a 20m x 0.21mm Carbowax 20M column supplied by Hewlett Packard. 120 Flash and conventional (gravity) column chromatographies were carried out by using 230-400 mesh s i l i c a gel (E. Merck) or neutral alumina (ICN Pharmaceuticals, Inc.) and with suitable solvent or solvent combinations. Thin layer chromatographic analyses were performed on pre-coated s i l i c a gel plates (type 5554 from E. Merck). Crystallographic Analyses A l l crystal structures were determined on a Rigaku 4-circle diffractometer by the following people: Dr. Phani Raj Pokkuluri, Ms. Christine Hwang, Dr. Steven J. Rettig and Dr. James Trotter of the UBC Chemistry Department. Solvents and Reagents 199 -U n l e s s o t h e r w i s e s p e c i f i e d , a l l t h e s o l v e n t s a n d r e a g e n t s w e r e u s e d d i r e c t l y w i t h o u t f u r t h e r p u r i f i c a t i o n . W h e n f u r t h e r p u r i f i c a t i o n 1 2 1 w a s n e e d e d , k n o w n m e t h o d s a n d p r o c e d u r e s w e r e f o l l o w e d i n e a c h c a s e . I I . S y n t h e s i s o f S u b s t r a t e s A . C y c l o h e x e n o n e D e r i v a t i v e s 1 - p - B r o m o p h e n y l - l - p h e n y l e t h y l e n e o x i d e ( 8 2 ) T h e p r e p a r a t i o n was t h e s a m e a s t h a t d e s c r i b e d b y Z i m m e r m a n et 53 al. p - B r o m o b e n z o p h e n o n e ( 2 0 g , 77 m m o l e s ) f r o m A l d r i c h d i s s o l v e d i n 40 mL o f d i m e t h y l s u l f o x i d e was a d d e d i n t o t h e d i m e t h y l o x o s u l f o n i u m m e t h y l i d e s o l u t i o n w h i c h w a s o b t a i n e d b y d r o p p i n g 90 mL o f DMSO i n t o a m i x t u r e o f s o d i u m h y d r i d e ( 4 . 8 g , c a . 60% p u r e ) a n d t r i m e t h y l o x o s u l f o n i u m i o d i d e (18 g , 82 m m o l e s ) u n d e r n i t r o g e n . T h e s o l u t i o n w a s s t i r r e d a t r o o m t e m p e r a t u r e f o r 1 h r a n d t h e n h e a t e d t o 5 0 -5 5 ° C f o r 2 h r . T h e h o t r e a c t i o n m i x t u r e w a s p o u r e d i n t o i c e w a t e r a n d q u i c k l y e x t r a c t e d w i t h d i e t h y l e t h e r . T h e e t h e r e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m , l e a v i n g 22 g o f a l i g h t y e l l o w o i l . . T h e i n f r a r e d s p e c t r u m s h o w e d n o p - b r o m o b e n z o p h e n o n e , b u t d i d e x h i b i t a -1 122 1 s t r o n g b a n d a t 908 c m , c h a r a c t e r i s t i c o f e p o x i d e s . H NMR a n d IR 53 s p e c t r a w e r e i n a g r e e m e n t w i t h t h o s e r e p o r t e d . T h i s c r u d e o i l w a s u s e d d i r e c t l y w i t h o u t f u r t h e r p u r i f i c a t i o n i n t h e n e x t s t e p . I R ( n e a t ) vmax: 1 5 9 4 , 1 4 8 7 , 1 4 4 8 , 1 3 9 7 , 1 0 7 3 , 1 0 1 0 , 9 0 8 , 8 2 4 , 760 7 0 0 c m " 1 . - 2 0 0 -NMR ( 6 0 M H z , CCI4) 5 : 7 . 2 (m , 9 H , a r o m a t i c H ) , 3 . 1 ( A B q , 2 H , J = 6 H z , CH2) p p m . 2 - p - B r o m o p h e n y l - 2 - p h e n y l a c e t a l d e h y d e ( 8 3 ) 53 T h e s a m e p r o c e d u r e d e s c r i b e d b y Z i m m e r m a n e t a l . w a s u s e d , p -T o l u e n e s u l f o n i c a c i d ( 1 . 0 g ) w a s r e f l u x e d i n 1 7 0 mL o f b e n z e n e f o r 2 h r u n d e r n i t r o g e n , a n d w a t e r w a s r e m o v e d w i t h a D e a n - S t a r k t u b e . F r e s h l y p r e p a r e d e p o x i d e 82 (22 g ) d i s s o l v e d i n 20 mL o f b e n z e n e was r a p i d l y a d d e d i n t o t h e a b o v e s o l u t i o n . T h e m i x t u r e w a s r e f l u x e d f o r 2 h r . T h e c o o l e d b e n z e n e s o l u t i o n w a s w a s h e d w i t h d i l u t e a q u e o u s s o d i u m b i c a r b o n a t e a n d w a t e r , d r i e d a n d c o n c e n t r a t e d i n v a c u u m , l e a v i n g 2 0 g o f a b r o w n o i l . I R a n d X H NMR s p e c t r a o f t h i s c r u d e o i l w e r e i n a g r e e m e n t 53 w i t h t h o s e r e p o r t e d a n d s h o w e d m a i n l y t h e a l d e h y d e . T h i s c r u d e m a t e r i a l w a s a l s o u s e d w i t h o u t f u r t h e r p u r i f i c a t i o n i n t h e f o l l o w i n g s t e p . I R ( n e a t ) i / m a x : 2 7 2 5 , 1 7 2 8 ( C = 0 ) , 1 4 8 8 , 1 0 7 4 , 1 0 1 1 , 8 2 2 , 7 0 1 c m " 1 . NMR ( 6 0 M H z , CCI4) 6: 9 . 7 ( d , I H , J = 2 H z , C H O ) , 7 . 2 ( m , 9 H , a r o m a t i c H ) , 4 . 8 ( d , I H , J = 2 H z , C H - C H O ) p p m . 4- P h e n y l - 4 - p - b r o m o p h e n y l - 2 - e y e l o h e x e n - 1 - o n e (7 l a ) T h e p r e p a r a t i o n w a s q u i t e s i m i l a r t o t h a t d e s c r i b e d b y Z i m m e r m a n e t al. ' T h e c r u d e a l d e h y d e 83 ( 1 0 g , 37 m m o l e s ) a n d m e t h y l v i n y l k e t o n e ( 2 . 9 g , 4 1 m m o l e s ) w e r e d i s s o l v e d i n 45 mL o f d i e t h y l e t h e r u n d e r n i t r o g e n i n a n i c e - c o o l i n g b a t h . A s o l u t i o n o f p o t a s s i u m h y d r o x i d e ( 1 . 6 g ) i n 10 mL o f 90% e t h a n o l w a s d r o p p e d s l o w l y i n t o t h e e t h e r s o l u t i o n d u r i n g 1 h r . T h e m i x t u r e was s t i r r e d u n d e r n i t r o g e n a t 0 ° C f o r 2 h r , - 2 0 1 -t h e n p o u r e d i n t o i c e w a t e r a n d n e u t r a l i z e d w i t h d i l u t e d h y d r o c h l o r i c a c i d . T h e a q u e o u s l a y e r w a s e x t r a c t e d w i t h d i e t h y l e t h e r . T h e c o m b i n e d e t h e r e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m , a f f o r d i n g 13 g o f a d a r k b r o w n o i l . T h i s o i l w a s c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 1 0 - 3 0 % d i e t h y l e t h e r i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t . I t p r o v i d e d 2 . 6 g ( y i e l d 21% f r o m p - b r o m o b e n z o p h e n o n e ) o f t h e s o l i d s a m p l e 7 1 a ) , w h i c h was r e c r y s t a l l i z e d f r o m d i e t h y l e t h e r a n d p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) g i v i n g l i g h t y e l l o w p r i s m s , m . p . , 1 2 3 - 1 2 4 ° C ( l i t . , 5 3 1 2 4 - 1 2 5 ° C ) . I R ( K B r ) i / m a x : 1 6 7 0 ( C = 0 ) , 1 6 0 0 (C=C) , 1 4 8 9 , 1 0 0 8 , 8 9 4 , 8 1 6 , 7 8 2 , 7 6 8 , 705 c m " 1 . X H NMR ( 3 0 0 MHz) 6: 7 . 5 0 - 7 . 1 0 (m, 1 0 H , a r o m a t i c H a n d C0CH=CH) , - 6 . 2 3 ( d , I H , J - 10 H z , C 0 C H = C H ) , 2 . 6 8 (m , 2 H , C O C H 2 C H 2 ) , 2 . 4 2 ( m , 2 H , C O C H 2 C H 2 ) p p m . 1 3 C NMR ( 5 0 MHz) 5 : 1 9 8 . 4 4 ( C = 0 ) , 1 5 5 . 3 4 , 1 4 4 . 7 3 , 1 4 4 . 6 6 , 1 3 1 . 7 0 , 1 2 9 . 4 3 , 1 2 9 . 2 7 , 1 2 8 . 7 5 , 1 2 7 . 5 6 , 1 2 7 . 1 5 , 1 2 0 . 9 9 ( v i n y l i c C a n d a r o m a t i c C ) , 4 9 . 0 1 ( q u a t e r n a r y C ) , 3 5 . 8 0 , 3 4 . 8 0 (2 x C H 2 ) p p m . U V ( C 6 H 6 ) A m a x : 3 4 1 nm ( n - » * , e = 4 3 ) . MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 2 8 (M+2, 9 ) , 326 ( M + , 9 ) , 284 ( 4 8 ) , 2 0 5 ( 1 0 0 ) , 1 8 9 ( 3 7 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 8 H i 5 B r O : 3 2 6 . 0 3 0 6 . F o u n d : 3 2 6 . 0 3 0 7 . A n a l , c a l c d . f o r C i g H ^ B r O : C , 6 6 . 0 7 ; H , 4 . 6 2 ; B r , 2 4 . 4 2 . F o u n d : C , 6 6 . 0 8 ; H , 4 . 6 8 ; B r , 2 4 . 4 0 . T h e s t r u c t u r e o f t h i s c o m p o u n d was a l s o s u p p o r t e d b y a n X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C ^ g H i ^ B r O , m o n o c l i n i c , s p a c e g r o u p P 2 1 / c , a = 1 6 . 1 5 6 7 ( 1 5 ) A , b = 9 . 1 8 8 6 ( 2 8 ) A , c -- 202 -9 . 9 9 5 9 ( 3 0 ) A , 0 = 9 5 . 8 0 ( 2 ) ° , V = 1 4 7 6 . 4 ( 7 ) A 3 , Z = 4 , D x - 1 . 4 7 2 g / m L , R = 0 . 0 4 8 . T h e d e t a i l s w e r e p u b l i s h e d e l s e w h e r e . ^ 4-Phenyl-4-p-cyanopheny1-2-eyelohexen-1-one (7lb) 53 T h e s a m e m e t h o d d e s c r i b e d b y Z i m m e r m a n et al. w a s u s e d . A m i x t u r e o f t h e c y c l o h e x e n o n e 71a ( 3 . 0 g , 9 . 2 m m o l e s ) a n d c u p r o u s c y a n i d e ( 1 . 6 g , 18 m m o l e s ) w a s r e f l u x e d i n 10 mL o f N - m e t h y l p y r r o l i d o n e f o r 2 h r . T h e r e a c t i o n m i x t u r e w a s c o o l e d a n d p o u r e d i n t o 5% a q u e o u s N a C N s o l u t i o n ( 6 0 m L ) . T h e r e s u l t i n g m i x t u r e was s h a k e n t h o r o u g h l y , 2 8 0 mL o f b e n z e n e w a s a d d e d a n d t h e m i x t u r e was s h a k e n a g a i n . T h e b e n z e n e l a y e r was s e p a r a t e d a n d w a s h e d w i t h 10% a q u e o u s s o d i u m c y a n i d e , w a t e r , d r i e d a n d c o n c e n t r a t e d i n v a c u u m l e a v i n g 2 . 6 g o f a d a r k b r o w n o i l . C h r o m a t o g r a p h y o n s i l i c a g e l b y u s i n g 1 0 - 2 0 % d i e t h y l e t h e r a n d p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t r e s u l t e d i n 1 . 6 g ( y i e l d 64%) o f c o m p o u n d 7 1 b . R e c r y s t a l l i z a t i o n f r o m d i e t h y l e t h e r a f f o r d e d w h i t e c r y s t a l s , m . p . , 7 9 - 8 0 ° C ( l i t . , 5 3 8 1 - 8 1 . 5 ° C ) . T h e s p e c t r o s c o p i c d a t a w e r e 53 i n a g r e e m e n t w i t h t h o s e r e p o r t e d . I R ( K B r ) i / m a x : 2 2 2 9 ( C N ) , 1 6 8 2 ( C = 0 ) , 1 6 0 6 , 1 4 9 3 , 1 4 4 7 , 8 9 1 , 8 3 4 , 698 c m ' 1 . 1 H NMR ( 3 0 0 M H z ) 6": 7 . 7 2 - 7 . 2 5 ( m , 1 0 H , a r o m a t i c H a n d C 0 C H = C H ) , 6 . 2 3 ( d , I H , J = 10 H z , C 0 C H = C H ) , 2 . 6 8 (m , 2 H , C 0 C H 2 ) , 2 . 4 2 ( m , 2H, COCH2CH2) p p m . 1 3 C NMR ( 5 0 M H z ) 6: 1 9 7 . 9 3 ( C = 0 ) , 1 5 4 . 2 8 , 1 5 1 . 2 5 , 1 4 3 . 8 0 , 1 3 2 . 4 1 , 1 2 9 . 7 9 , 1 2 8 . 9 6 , 1 2 8 . 4 7 , 1 2 7 . 5 5 , 1 2 7 . 4 5 , 1 1 8 . 4 7 , 1 1 0 . 9 6 ( C H = C H , CN a n d a r o m a t i c C ) , 4 9 . 5 2 ( q u a t e r n a r y C ) , 3 5 . 6 3 , 3 4 . 6 7 (CH2CH2) p p m . - 203 -MS m / e ( r e l a t i v e i n t e n s i t y ) : 2 7 3 ( M + , 6 ) , 2 4 5 (11), 2 3 1 (100), 216 ( 1 6 ) , 1 1 5 ( 2 6 ) . E x a c t m a s s c a l c u l a t e d f o r C19H15NO: 2 7 3 . 1 1 5 5 . F o u n d : 2 7 3 . 1 1 5 7 . A n a l , c a l c d . f o r C 1 9 H 1 5 N O : C, 8 3 . 4 9 ; H, 5.53; N , 5.12. F o u n d : C, 8 3 . 4 9 ; H , 5.53; N , 5 .00. P r e p a r a t i o n o f 4 , 4 - d i p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 3 6 a ) / 0 T h e s a m e p r o c e d u r e s d e s c r i b e d b y Z i m m e r m a n et al. w e r e p e r f o r m e d . A m i x t u r e o f 2 5 . 0 g ( 0 . 1 2 7 m o l e s ) o f d i p h e n y l a c e t a l d e h y d e f r o m A l d r i c h a n d 9 . 0 g ( 0 . 1 3 m o l e s ) o f m e t h y l v i n y l k e t o n e i n 200 mL o f d i e t h y l e t h e r was s t i r r e d u n d e r n i t r o g e n i n a n i c e - c o o l i n g b a t h . A s o l u t i o n o f 3 . 0 g ( 0 . 0 5 4 m o l e s ) o f p o t a s s i u m h y d r o x i d e i n 15 mL o f 95% e t h a n o l w a s a d d e d s l o w l y d u r i n g 20 m i n . A f t e r s t i r r i n g f o r a n a d d i t i o n a l 4 0 m i n a t 0 ° C , t h e m i x t u r e was p o u r e d i n t o i c e w a t e r a n d t h e s o l u t i o n w a s n e u t r a l i z e d w i t h d i l u t e HC1. T h e a q u e o u s l a y e r w a s e x t r a c t e d w i t h e t h e r a n d t h e e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m . T h e o i l y r e s i d u e was d i s s o l v e d i n h o t e t h a n o l a n d c r y s t a l l i z a t i o n r e s u l t e d o n c o o l i n g . R e c r y s t a l l i z a t i o n o f t h e c r u d e s o l i d s f r o m e t h a n o l a f f o r d e d 1 4 . 0 g ( y i e l d 42%) o f c o l o r l e s s p r i s m s , m . p . , 9 0 - 9 3 ° C ( l i t . , 4 2 9 1 - 9 4 ° C ) . I R ( K B r ) i / m a x : 1 6 7 3 (C=0) , 1 5 9 7 , 7 6 5 , 706 c m " 1 . X H NMR ( 4 0 0 MHz) 6: 7 . 4 - 7 . 2 (m, 11H, a r o m a t i c H a n d C0CH=CH), 6 .22 ( d , I H , J = 10 H z , C0CH=CH), 2 . 7 1 ( t , 2H, J = 7 H z , C O C H 2 C H 2 ) , 2 . 4 2 ( t , 2H, J = 7 H z , C O C H 2 C H 2 ) p p m . - 2 0 4 -^ C NMR (50 MHz) 8: 1 9 8 . 8 6 ( C = 0 ) , 1 5 6 . 2 1 , 1 4 5 . 4 3 , 1 2 9 . 0 0 , 1 2 8 . 2 1 , 1 2 7 . 6 7 , 1 2 6 . 8 8 (CH=CH a n d a r o m a t i c C ) , 4 9 . 3 1 ( q u a t e r n a r y C ) , 3 5 . 9 2 , 3 4 . 9 6 ( C H 2 C H 2 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 2 4 8 ( M + , 2 2 ) , 2 1 9 ( 1 8 ) , 206 ( 1 0 0 ) , 1 9 1 ( 2 8 ) , 91 ( 3 7 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 8 H 1 6 0 : 2 4 8 . 1 2 0 2 . F o u n d : 2 4 8 . 1 2 0 2 . A n a l , c a l c d . f o r C 1 8 H x 6 0 : C , 8 7 . 0 6 ; H , 6 . 5 0 . F o u n d : C , 8 7 . 1 2 ; H , 6 . 4 5 . P r e p a r a t i o n o f 4 , 4 - d i p h e n y l - 6 - m e t h y l - 2 - c y c l o h e x e n - l - o n e ( 7 4 a ) D i i s o p r o p y l a m i n e ( 1 . 1 g , 11 m m o l e s ) w a s d i s s o l v e d i n 10 mL o f a n h y d r o u s T H F a n d t h e s o l u t i o n w a s c o o l e d t o - 1 0 ° C . T o t h e s o l u t i o n , n -B u L i i n h e x a n e ( c a . 0 . 9 7 M , 12 mL) w a s a d d e d a n d t h e m i x t u r e was s t i r r e d a t - 1 0 ° C f o r 30 m i n . 4 , 4 - D i p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 2 . 0 g , 8 . 1 m m o l e s ) i n 10 mL o f a n h y d r o u s T H F was a d d e d a t - 7 8 ° C a n d t h e m i x t u r e w a s k e p t s t i r r i n g f o r a n a d d i t i o n a l 30 m i n . N e x t , m e t h y l i o d i d e ( 6 . 0 m L , 96 m m o l e s ) p a s s e d t h r o u g h b a s i c a l u m i n a w a s d r o p p e d i n t o t h e a b o v e s o l u t i o n a n d t h e r e s u l t i n g m i x t u r e w a s s t i r r e d a t 0 ° C f o r 5 h r a n d t h e n 10 h r a t r o o m t e m p e r a t u r e . T h e s l i g h t l y y e l l o w s o l u t i o n w a s p o u r e d i n t o a n a q u e o u s NH4CI s o l u t i o n ( c o n e . ca. 0 . 5 M ) . T h e o r g a n i c l a y e r was s e p a r a t e d a n d t h e a q u e o u s , l a y e r w a s e x t r a c t e d w i t h d i e t h y l e t h e r . T h e c o m b i n e d e t h e r e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m g i v i n g 2 . 2 g o f a y e l l o w o i l . C h r o m a t o g r a p h y o f t h i s o i l o n s i l i c a g e l b y u s i n g 10% d i e t h y l e t h e r i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t a f f o r d e d 1 . 2 g ( y i e l d 57%) o f a c o l o r l e s s o i l w h i c h was c r y s t a l l i z e d f r o m m e t h y l c y c l o h e x a n e a s c o l o r l e s s c r y s t a l s , m . p . , 9 9 . 5 -- 2 0 5 -1 0 0 . 5 ° C ( l i t . , ' 1 0 1 - 1 0 3 ° C ) . T h e s p e c t r o s c o p i c d a t a w e r e i n a g r e e m e n t w i t h t h o s e r e p o r t e d . I R ( K B r ) i / m a x : 1 6 7 7 (C=0) , 1 4 9 2 , 1 4 4 7 , 1 3 8 0 , 7 5 6 , 7 0 3 c m " 1 . ^•H NMR ( 4 0 0 M H z ) 5 : 7 . 4 5 - 7 . 1 5 ( m , 1 1 H , a r o m a t i c H a n d C 0 C H = C H ) , 6 . 2 0 ( d , I H , J - 10 H z , C 0 C H = C H ) , 2 . 7 0 - 2 . 4 0 (m , 3 H , C H 2 a n d C H ) , 1 . 1 4 ( d , 3 H , J - 6 . 5 H z , C H 3 ) p p m . 1 3 C NMR ( 7 5 MHz) S: 2 0 1 . 2 4 ( C = 0 ) , 1 5 5 . 0 5 , 1 4 7 . 7 3 , 1 4 3 . 4 4 , 1 2 8 . 6 1 , 1 2 8 . 5 3 * , 1 2 7 . 9 3 , 1 2 7 . 1 2 , 1 2 6 . 8 8 , 1 2 6 . 6 6 ( v i n y l i c CH a n d a r o m a t i c C ) , 4 9 . 9 6 ( q u a t e r n a r y C ) , 4 4 . 4 5 ( C H 2 ) , 3 8 . 2 9 (CHCH3), 1 4 . 7 6 (CHCH3) p p m . P o s s i b l y two c a r b o n s h e r e . MS m / e ( r e l a t i v e i n t e n s i t y ) : 262 ( M + , 2 0 ) , 2 3 4 ( 2 0 ) , 2 0 6 ( 1 0 0 ) , 1 9 1 ( 4 0 ) , 91 ( 6 5 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 9 H i 8 0 : 2 6 2 . 1 3 5 8 ; F o u n d : 2 6 2 . 1 3 5 5 . A n a l , c a l c d . f o r C 1 9 H 1 8 0 : C , 8 6 . 9 9 ; H , 6 . 9 1 . F o u n d : C , 8 7 . 1 7 ; H , 6 . 9 6 . 4 , 4 - D i p h e n y l - 6 - e t h y l - 2 - c y c l o h e x e h - l - o n e ( 7 4 b ) T h e e x a c t p r o c e d u r e s w e r e f o l l o w e d a s i n t h e p r e p a r a t i o n o f c o m p o u n d 7 4 a e x c e p t t h a t t h e m e t h y l i o d i d e w a s r e p l a c e d b y e t h y l i o d i d e ( p a s s e d t h r o u g h b a s i c a l u m i n a p r i o r t o u s e ) . S t a r t i n g w i t h 2 . 0 g o f t h e c y c l o h e x e n o n e ( 3 6 a ) , a c r u d e b r o w n o i l 7 4 b ( 2 . 2 g ) w a s o b t a i n e d . P u r i f i c a t i o n o f t h i s o i l b y c o l u m n c h r o m a t o g r a p h y o n s i l i c a g e l b y u s i n g 5% d i e t h y l e t h e r i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t g a v e 7 1 0 mg (95% p u r e ) o f a c o l o r l e s s o i l 7 4 b . T h e s p e c t r o s c o p i c d a t a a r e a s f o l l o w s . . - 206 -I R ( n e a t ) i / m a x : 1 6 8 0 ( C = 0 ) , 1598 ( C = C ) , 1 4 9 4 , 1 4 4 7 , 1 3 8 2 , 1 1 8 9 , 7 5 5 , 7 0 1 c m " 1 . 1 H NMR ( 3 0 0 MHz) 6: 7 . 4 - 7 . 1 (m , 11H, COCH=CH a n d a r o m a t i c H ) , 6 . 2 0 ( d , J = 10 H z , C 0 C H = C H ) , 2 . 8 - 1 . 4 ( m , 5 H , C H 2 C H 3 a n d C 0 C H ( E t ) C H 2 ) , 0 . 9 2 ( t , 3 H , J - 7 H z , C H 2 C H 3 ) p p m . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 276 ( M + , 5 ) , 2 4 8 ( 1 0 ) , 219 ( 2 2 ) , 2 0 6 ( 1 0 0 ) , 1 9 1 ( 2 3 ) , 1 6 5 ( 1 5 ) , 115 ( 2 4 ) , 9 1 ( 4 1 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 o H 2 0 0 : 2 7 6 . 1 5 1 1 . F o u n d f r o m h i g h r e s o l u t i o n G C - M S : 2 7 6 . 1 5 3 0 . B . D i b e n z o b a r r e l e n e D e r i v a t i v e s . Me t h y 1 3 , 5 - D i h y d r o - 3 - o x o - III - 5 , 9b [ 1 ' , 2 ' ] - b e n z e n o n a p h t h o [ 1 , 2 - c ] f u r a n - 4 -c a r b o x y l a t e ( 9 6 ) A m i x t u r e o f 9 - a n t h r a c e n e m e t h a n o l ( 4 . 0 g , 19 m m o l e s , A l d r i c h ) a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( 3 . 5 g , 25 m m o l e s , A l d r i c h ) was h e a t e d a t 1 5 0 - 1 6 0 ° C f o r 3 h r . T h e c o o l e d s o l i d was r e c r y s t a l l i z e d f r o m CHCI3 /CH3OH, a f f o r d i n g 1 . 8 g ( y i e l d 30%) o f s l i g h t l y b r o w n c r y s t a l s . C o l o r l e s s p r i s m s w e r e o b t a i n e d b y r e f l u x i n g c o m p o u n d 96 i n CHCI3 a n d CH3OH w i t h c h a r c o a l a n d t h e n r e c r y s t a l l i z a t i o n f r o m t h e s a m e s o l v e n t m i x t u r e a f t e r t h e r e m o v a l o f t h e c h a r c o a l , m . p . , 1 7 0 - 1 7 1 . 5 ° C . I R ( K B r ) » / r a a x : 1 7 6 7 ( l a c t o n e C « 0 ) , 1709 ( C = 0 ) , 1 6 4 7 , 1 4 5 6 , 1 4 3 7 , 1 3 1 0 , 1 2 4 8 , 1 2 3 0 , 1 1 7 7 , 1 1 1 4 , 1 0 3 9 , 7 5 5 , 7 3 4 , 7 1 3 c m ' 1 . 1 H NMR ( 4 0 0 MHz) 5: 7 . 5 5 - 7 . 0 5 (m, 8 H , a r o m a t i c H) , 5 . 8 2 ( s , I H , C H ) , 5 . 5 5 ( s , 2 H , C H 2 ) , 3 . 8 9 ( s , 3 H , C H 3 ) p p m . - 2 0 7 1 3 C NMR ( 7 5 MHz ) 5 : 1 6 3 . 4 5 , 1 6 3 . 3 8 ( 2 x C = 0 ) , 1 2 0 . 6 5 , 1 2 4 . 6 9 , 1 2 5 . 5 2 , 1 2 6 . 0 9 , 1 4 2 . 6 4 , 1 4 2 . 9 8 , 1 4 4 . 5 3 , 1 4 7 . 5 3 ( v i n y l i c C a n d a r o m a t i c C ) , 6 4 . 6 4 ( C H 2 ) , 5 8 . 6 7 ( b r i d g e h e a d C ) , 5 4 . 4 4 ( C H 3 ) , 5 2 . 6 9 ( b r i d g e h e a d CH) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 1 8 ( M + , 8 ) , 2 9 0 ( 2 9 ) , 2 6 2 ( 2 4 ) , 2 3 0 ( 3 9 ) , 2 1 5 ( 3 7 ) , 2 0 2 ( 1 0 0 ) , 101 ( 2 7 ) . E x a c t m a s s c a l c u l a t e d f o r C20H14O4: 3 1 8 . 0 8 9 2 ; F o u n d : 3 1 8 . 0 8 9 0 . A n a l , c a l c d . f o r C20H14O4: C , 7 5 . 4 6 ; H , 4 . 4 3 . F o u n d : 7 5 . 2 8 ; H , 4 . 5 0 . U V (MeOH) A m a x : 2 1 2 ( e , 2 9 2 0 0 ) , 2 2 8 s h . ( e , 2 5 0 0 ) n m . T h e s t r u c t u r e o f t h i s c o m p o u n d w a s s u p p o r t e d b y t h e X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C20H14O4. o r t h o r h o m b i c , s p a c e g r o u p P 2 T 2 I 2 I , a = 1 0 . 3 4 9 1 ( 8 ) , b = 1 6 . 6 2 0 4 ( 9 ) , c = 8 . 9 9 3 3 ( 6 ) A , V = 1 5 4 6 . 9 ( 2 ) A 3 , Z - 4 , D x = 1 . 3 7 g / m L , R - 0 . 0 3 8 . T h e d e t a i l s w i l l b e p u b l i s h e d e l s e w h e r e . P r e p a r a t i o n o f a - M e t h y l - 9 - a n t h r a c e n e m e t h a n o l ( 9 1 ) 9 - A n t h r a l d e h y d e ( 9 0 ) ( 1 . 5 g , 7 . 3 m m o l e s , A l d r i c h ) i n 2 0 mL o f a n h y d r o u s b e n z e n e w a s d r o p p e d i n t o t h e G r i g n a r d s o l u t i o n p r e p a r e d f r o m 0 . 3 0 g ( 1 2 m m o l e s ) o f m a g n e s i u m a n d 1 . 4 0 g ( 9 . 9 m m o l e s ) o f m e t h y l i o d i d e i n 2 0 mL o f a n h y d r o u s d i e t h y l e t h e r . T h e m i x t u r e w a s r e f l u x e d f o r 3 0 m i n a n d t h e n p o u r e d i n t o 1 0 0 mL o f i c e w a t e r c o n t a i n i n g 2 mL o f c o n c e n t r a t e d H C l . T h e o r g a n i c l a y e r w a s s e p a r a t e d a n d t h e a q u e o u s l a y e r w a s e x t r a c t e d w i t h e t h e r ( 2 x 5 0 m L ) . T h e c o m b i n e d e t h e r e x t r a c t s w e r e w a s h e d a n d d r i e d . R e m o v a l o f t h e s o l v e n t s i n v a c u u m l e f t 1 . 6 g o f a y e l l o w s o l i d - 208 -which was recrystallized from ether/hexane affording 1.1 g (yield 68%) of yellow needle crystals, m.p., 124-126°C ( l i t . , 6 0 125-126.5°C). IR (KBr) i / m a x : 3301 (OH), 1686, 1367, 1114, 1067, 1046, 890, 730 cm"1. XH NMR (400 MHz) 6: 8.75-7.40 (m, 9H, aromatic H), 6.48 (q, IH, J = 7 Hz, CH), 2.23 (s, IH, D20 exchangeable, OH), 1.92 (d, 3H, J = 7 Hz, CH3) ppm. MS m/e (relative intensity): 222 (M +, 26), 207 (24), 179 (100). Exact mass calculated for C^H^O: 222.1045. Found: 222.1043. Anal, calcd. for C 1 6H 1 40: C, 86.45; H, 6.35. Found: C, 86.56; H, 6.29. Preparation of Methyl l-Methyl-3,5-dihydro-3-oxo-lH-5,9b[l',2']-benzenonaphthofl,2-c]furan-4-carboxylate (97) A mixture of 500 mg (2.3 mmoles) of Q-methyl-9-anthracenemethanol (91) prepared above and 500 mg (3.5 mmoles) of dimethyl acetylenedicarboxylate was heated at 140-150°C for 6 hr. The crude solid was chromatographed on s i l i c a gel by using 30% ethyl acetate in petroleum ether (30-60°) as the eluting solvent. This afforded 680 mg (yield 91%) of a white solid, which was recrystallized from methanol and methylene chloride to give colorless prisms, m.p., 191-192°C. IR (KBr) i / m a x : 1767 (lactone C=0), 1736 (C=0), 1680 (C=C), 1456, 1433, 1285, 1230, 1145, 1078, 1011, 910, 763, 741, 719 cm"1." - 2 0 9 -•"-H NMR ( 3 0 0 MHz) 5 : 7 . 8 2 - 7 . 0 0 (m, 8 H , a r o m a t i c H ) , 5 . 9 6 ( q , I H , J = 7 H z , C H ) , 5 . 7 9 ( s , I H , b r i d g e h e a d C H ) , 3 . 8 9 ( s , 3 H , COOCH3), 2 . 3 0 ( d , 3 H , J = 7 H z , CHCH3) p p m . 1 3 C NMR ( 7 5 M H z ) 8: 1 6 3 . 7 1 , 1 6 3 . 0 9 ( 2 x C = 0 ) , 1 4 7 . 9 5 , 1 4 5 . 7 4 , 1 4 4 . 5 4 , 1 4 4 . 0 6 , 1 4 2 . 5 9 , 1 2 6 . 0 0 , 1 2 5 . 7 2 , 1 2 5 . 4 9 , 1 2 5 . 2 2 , 1 2 4 . 7 8 , 1 2 4 . 4 7 , 1 2 3 . 2 4 , 1 2 1 . 3 2 ( v i n y l i c C a n d a r o m a t i c C) , 7 7 . 2 ( C 0 2 C H 3 ) , 6 1 . 0 1 ( q u a t e r n a r y C ) , 5 5 4 . 7 3 , 5 2 . 7 4 (2 x C H ) , 1 9 . 2 0 (CHCH3) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 332 ( M + , 8 ) , 3 0 4 ( 1 6 ) , 272 ( 3 9 ) , 262 ( 4 7 ) , 244 ( 3 1 ) , 229 ( 4 6 ) , 202 ( 1 0 0 ) , 189 ( 1 2 ) , 1 0 0 ( 2 2 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 i H 1 6 0 4 : 3 3 2 . 1 0 4 9 . F o u n d : 3 3 2 . 1 0 4 4 . A n a l , c a l c d . f o r C 2 1 H 1 6 0 4 : C , 7 5 . 8 9 ; H , 4 . 8 5 . F o u n d : C , 7 5 . 9 5 ; H , 4 . 8 5 . P r e p a r a t i o n o f 9 - A n t h r y l m e t h y l P r o p y n o a t e ( 8 9 c ) P r o c e d u r e ( a ) 9 - A n t h r a c e n e m e t h a n o l ( 2 . 0 g , 9 . 6 m m o l e s ) a n d p r o p i o l i c a c i d ( 1 . 0 g , 14 m m o l e s ) i n 50 mL o f b e n z e n e w e r e r e f l u x e d f o r 8 h r . T h e r e a c t i o n m i x t u r e w a s c o o l e d t o r o o m t e m p e r a t u r e a n d a n a d d i t i o n a l 100 mL o f b e n z e n e w e r e a d d e d . T h e b e n z e n e l a y e r w a s w a s h e d w i t h d i l u t e a q u e o u s s o d i u m b i c a r b o n a t e , w a t e r a n d d r i e d . R e m o v a l o f t h e s o l v e n t l e f t 2 . 5 g o f a y e l l o w s o l i d . T h e c r u d e s o l i d w a s p u r i f i e d b y c h r o m a t o g r a p h y o n s i l i c a g e l b y u s i n g 10% e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t t o a f f o r d 2 . 2 g ' ( y i e l d 88%) o f a y e l l o w s o l i d . R e c r y s t a l l i z a t i o n f r o m a c e t o n e / c y c l o h e x a n e g a v e y e l l o w n e e d l e c r y s t a l s , m . p . , 9 8 - 1 0 0 ° C ( l i t " 1 2 3 , 9 4 - 9 5 ° C ) . IR ( K B r ) y m a x : 3277 ( C = C - H ) , 2 1 1 9 ( C ^ C ) , 1 7 1 8 ( C = 0 ) , 1 2 5 4 , 9 2 7 , 8 7 9 , 7 4 9 , 731 c m " 1 . - 2 1 0 -X H NMR ( 3 0 0 MHz) 5 : 8 . 5 8 - 7 . 4 5 ( m , 9 H , a r o m a t i c H ) , 6 . 2 8 ( s , 2 H , C H 2 ) , 2 . 8 5 ( s , I H , CH) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) ; 2 6 0 ( M + , 2 7 ) , 2 1 5 ( 1 0 ) , 1 9 1 ( 1 0 0 ) , 178 ( 1 7 ) , 165 ( 1 0 ) . E x a c t m a s s c a l c u l a t e d f o r C i 8 H 1 2 ° 2 : 2 6 0 . 0 8 3 8 . F o u n d : 2 6 0 . 0 8 3 7 . P r o c e d u r e ( b ) A m i x t u r e o f 9 - c h l o r o m e t h y l a n t h r a c e n e ( 9 0 8 m g , 4 m m o l e s ) , p r o p i o l i c a c i d ( 4 0 0 m g , 6 m m o l e s ) a n d t r i e t h y l a m i n e ( 1 . 0 mL) i n 10 mL o f a c e t o n i t r i l e was r e f l u x e d f o r 4 h r . T h e s o l v e n t w a s r e m o v e d b y e v a p o r a t i o n i n v a c u u m , a n d t h e r e s u l t i n g m i x t u r e w a s c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 1 0 - 1 5 % e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t t o g i v e 5 5 0 mg ( y i e l d 50 %) o f c o m p o u n d 8 9 c . P r e p a r a t i o n o f 3 , 5 - D i h y d r o - l H - 5 , 9 b [ l ' , 2 ' ] - b e n z e n o n a p h t h o [ 1 , 2 - c ] f u r a n - 3 -o n e ( 9 8 ) 9 - A n t h r y l m e t h y l p r o p y n o a t e ( 8 9 c ) ( 8 0 0 mg) w a s h e a t e d a t 1 3 0 - 1 4 0 ° C f o r 4 h r . T h e r e s u l t i n g c r u d e s o l i d w a s p u r i f i e d b y c h r o m a t o g r a p h y o n s i l i c a g e l b y u s i n g 15% e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t t o a f f o r d 4 7 0 mg ( y i e l d 59%) o f a y e l l o w s o l i d w h i c h was r e c r y s t a l l i z e d f r o m a c e t o n e / h e x a n e t o g i v e c o l o r l e s s p r i s m s , m . p . , 2 4 7 -2 4 8 ° C . I R ( K B r ) i / m a x : 1 7 4 7 ( C = 0 ) , 1 6 5 4 (C=C) , 1 4 5 6 , 1 2 5 9 , 1 1 9 2 , 1 1 3 2 , 1 0 3 9 , 1 0 2 3 , 1 0 1 2 , 7 6 4 , 7 5 0 , 7 2 0 c m " 1 . lE NMR ( 3 0 0 MHz) 6 : 7 . 8 2 ( d , I H , J = 7 H z , v i n y l i c C H ) , 7 . 4 5 - 6 . 9 5 (m, 8 H , a r o m a t i c H ) , 5 . 5 3 ( s , 2 H , C H 2 ) , 5 . 4 2 ( d , I H , J = 7 H z , C H ) p p m . - 211 J - 5 C NMR (50 MHz) 6: 1 6 6 . 7 3 ( C = 0 ) , 1 4 5 . 4 8 ( v i n y l i c C H ) , 1 4 4 . 1 3 , 1 4 3 . 8 3 , 1 4 2 . 8 6 , 1 2 5 . 2 4 , 1 2 0 . 3 9 ( v i n y l i c C a n d a r o m a t i c C ) , 6 5 . 5 1 ( C H 2 ) , 5 7 . 4 1 ( q u a t e r n a r y C ) , 5 3 . 2 0 ( C H ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 2 6 0 ( M + , 4 3 ) , 232 ( 2 6 ) , 2 1 5 ( 1 0 0 ) , 2 0 3 ( 5 6 ) , 1 0 7 ( 6 ) . E x a c t m a s s c a l c u l a t e d for C i 8 H 1 2 ° 2 : 2 6 0 . 0 8 3 8 . F o u n d : 2 6 0 . 0 8 3 5 . A n a l , c a l c d . f o r C 1 8 H 1 2 0 2 : C , 8 3 . 0 6 ; H , 4 . 6 5 . F o u n d : C , 8 2 . 8 0 ; H , 4 . 6 7 . P r e p a r a t i o n o f 9 - A n t h r y l m e t h y l A c e t a t e ( 8 7 ) 9 - A n t h r a c e n e m e t h a n o l ( 1 . 0 g , 4 . 8 m m o l e s ) a n d a c e t y l c h l o r i d e ( 0 . 5 0 g , 6 . 4 m m o l e s ) i n 10 mL o f a n h y d r o u s b e n z e n e c o n t a i n i n g a s m a l l a m o u n t o f t r i e t h y l a m i n e w e r e r e f l u x e d f o r 2 . 5 h r . U p o n c o o l i n g , a n a d d i t i o n a l 4 0 mL o f b e n z e n e was a d d e d a n d t h e o r g a n i c l a y e r was w a s h e d w i t h d i l u t e a q u e o u s s o d i u m b i c a r b o n a t e , w a t e r a n d d r i e d . C o n c e n t r a t i o n i n v a c u u m a f f o r d e d 1 . 0 g o f a y e l l o w s o l i d . R e c r y s t a l l i z a t i o n o f t h e c r u d e s o l i d f r o m e t h a n o l g a v e 0 . 8 0 g ( y i e l d 67%) o f y e l l o w n e e d l e c r y s t a l s , m . p . , 1 1 0 - 1 1 1 C C ( l i t . 1 2 4 , 1 1 1 - 1 1 2 ° C ) . I R ( K B r ) i > m a x : 1 7 2 8 ( C = 0 ) , 1 2 4 6 , 8 8 9 , 734 c m " 1 . X H NMR ( 4 0 0 MHz) 5 : 8 . 5 5 - 7 . 4 8 (m, 9 H , a r o m a t i c H) , 6 . 1 8 ( s , 2 H , C H 2 ) , 2 . 1 0 ( s , 3 H , C H 3 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 2 5 0 ( M + , 7 5 ) , 1 9 1 ( 1 0 0 ) , 1 7 9 ( 5 7 ) , 1 6 5 ( 2 4 ) , 1 5 1 ( 1 4 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 7 H 1 4 0 2 : 2 5 0 . 0 9 9 4 . F o u n d : 2 5 0 . 0 9 9 2 . A n a l , c a l c d . f o r C 1 7 H i 4 0 2 : C , 8 1 . 5 8 ; H , 5 . 6 4 . F o u n d : C , 8 1 . 4 5 ; H , 5 . 8 0 . - 212 -P r e p a r a t i o n o f D i m e t h y l 9 , 1 0 - D i h y d r o - 9 - a c e t o x y m e t h y l - 9 , 1 0 - e t h e n o -a n t h r a c e n e - 1 1 , 1 2 - d i c a r b o x y l a t e ( 9 3 c ) A m i x t u r e o f 5 0 0 mg ( 2 . 0 m m o l e s ) o f 9 - a n t h r y l m e t h y l a c e t a t e (87) a n d 3 0 0 mg (2.2 m m o l e s ) o f d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e w a s h e a t e d a t 1 5 0 - 1 6 0 ° C f o r 3 h r . T h e r e s u l t i n g s o l i d w a s r e c r y s t a l l i z e d f r o m c h l o r o f o r m / e t h a n o l t o g i v e 4 4 0 mg ( y i e l d 56%) o f t h e t i t l e c o m p o u n d 9 3 c a s y e l l o w c r y s t a l s . F u r t h e r p u r i f i c a t i o n b y c o l u m n c h r o m a t o g r a p h y a n d r e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e a f f o r d e d c o l o r l e s s p r i s m s w i t h m . p . 1 6 1 . 5 - 1 6 2 . 5 ° C . I R ( K B r ) i / m a x : 1 7 3 7 ( O O ) , 1 7 1 3 ( O O ) , 1 6 2 8 ( O C ) , 1 4 6 0 , 1 4 3 6 , 1 2 9 4 , 1 2 4 0 , 1 1 2 9 , 1 0 9 4 , 1 0 6 8 , 7 4 9 , 616 c m " 1 . 1 H NMR ( 4 0 0 MHz) 6: 7 . 4 7 - 7 . 0 1 (m, 8 H , a r o m a t i c H ) , 5 . 6 3 ( s , I H , C H ) , 5 . 4 5 ( s , 2 H , C H 2 ) , 4 . 7 7 ( s , 3 H , OCH3), 4 . 7 6 ( s , 3 H , OCH3), 2 . 1 4 ( s , 3 H , COCH3) p p m . 1 3 C NMR ( 7 5 MHz) 6: 1 7 0 . 5 5 , 1 6 6 . 8 4 , 1 6 3 . 8 2 (3 x O O ) , 1 5 0 . 8 7 , 1 4 5 . 3 1 , 1 4 3 . 6 9 , 1 4 2 . 7 1 , 1 2 5 . 5 2 , 1 2 5 . 2 2 , 1 2 3 . 8 3 , 1 2 1 . 6 5 ( v i n y l i c C a n d a r o m a t i c C ) , 6 0 . 8 2 ( C H 2 ) , 5 4 . 7 3 ( b r i d g e h e a d C ) , 5 2 . 4 2 , 5 2 . 1 9 , 5 0 . 5 7 ( b r i d g e h e a d CH a n d 2 x OCH3), 2 0 . 5 7 (COCH3) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 392 ( M + , 3 9 ) , 3 5 0 ( 1 8 ) , 3 3 2 ( 1 7 ) , 318 ( 2 1 ) , 2 9 0 ( 1 0 0 ) , 273 ( 2 4 ) , 2 6 0 ( 6 2 ) , 2 0 2 ( 4 7 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 3 H 2 0 ° 6 : 3 9 2 . 1 2 6 0 . F o u n d : 3 9 2 . 1 2 5 8 . UV (MeOH) A m a x : 213 ( e , 5 4 , 0 0 0 ) n m . A n a l , c a l c d . f o r C 2 3 H 2 0 O 6 : C , 7 0 . 4 0 ; H , 5 . 1 4 . F o u n d : C , 7 0 . 2 9 ; H , 5 . 1 0 . - 213 -Dimethyl 9,10-dihydro-9-formyl-9,10-ethenoanthracene-ll,12-dicarboxylate (94) A mixture of 9-anthraldehyde (5.0 g, 24 mmoles, Aldrich) and dimethyl acetylenedicarboxylate (5.5 g, 39 mmoles) was heated at 170-190°C for 2 hr. The crude product was dissolved in 10 mL of ethyl acetate under refluxing. Crystallization occurred upon cooling and standing overnight; yellow crystals (5.5 g) were collected by f i l t r a t i o n and washing with cold benzene. Recrystallization from benzene gave 4.5 g of yellow crystals (yield 53%). Colorless prisms were obtained by chromatography on s i l i c a gel by using 20% ethyl acetate in petroleum ether (30-60°) as the eluting solvent and then recrystallization from benzene, m.p., 171-173°C. IR (KBr) r / m a x : 2760 (CHO), 1727 (C=0) , 1631 (C=C) , 1280, 1219, 760, 618 cm"1. 1H NMR (400 MHz) 5: 10.83 (s, IH, CHO), 7.55-7.05 (m, 8H, aromatic H), 5.64 (s, IH, CH), 3.85 (s, 3H, 0CH 3 ), 3.78 (s, 3H, OCH3) ppm. 1 3C NMR (50 MHz) 5: 197.39 (CHO), 166.46, 163.81 (2 x C=0) , 148.72, 144.51, 144.27, 141.68, 128.34, 126.16, 125.42, 125.09, 124.47, 122.27 (vinylic C and aromatic C), 64.18 (bridgehead C), 52.59*, 50.97 (2 x CO2CH3 and bridgehead CH) ppm. Possibly two carbons here. MS m/e (relative intensity): 348 (M +, 21), 316 (23), 290 (19), 260 (100), 229 (37), 202 (84). Exact mass calculated for C 2 i H 1 6 0 5 : 348.0998; Found: 348.1000. Anal, calcd. for C 2 i H 1 6 0 5 : C, 72.40; H, 4.63. Found: C, 72.48; H, 4.80. - 2 1 4 -T h e s t r u c t u r e o f t h i s c o m p o u n d w a s a l s o c o n f i r m e d b y a n X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C21H15O5, t r i c l i n i c , s p a c e g r o u p P l , a = 1 0 . 1 7 6 ( 1 ) , b = 1 2 . 0 7 5 ( 2 ) , c = 8 . 0 7 7 (1)A, a = 1 0 8 . 8 8 ( 1 ) , 0 = 1 1 2 . 7 9 ( 1 ) , 7 = 8 3 . 8 6 ( 1 ) ° , V = 8 6 5 . 6 ( 2 ) A 3 , Z = 2 , D x - 1 . 3 4 g / m L , R - 0 . 0 4 0 . T h e d e t a i l s w i l l b e p u b l i s h e d e l s e w h e r e . D i m e t h y 1 9 , 1 0 - d i h y d r o - 9 - h y d r o x y m e t h y l - 9 , 1 0 - e n t h e n o a n t h r a c e n e e - 1 1 , 1 2 -d i c a r b o x y l a t e ( 9 5 ) P o w d e r e d s a m p l e o f d i m e t h y l - 9 . 1 0 - d i h y d r o - f o r m y l - 9 , 1 0 - e t h e n o -a n t h r a c e n e - 1 1 , 1 2 - d i c a r b o x y l a t e ( 9 4 ) ( 2 . 0 g , 5 . 7 m m o l e s ) w a s s u s p e n d e d i n 20 mL o f m e t h a n o l a t 0 ° C a n d 1 3 0 mg ( 3 . 4 m m o l e s ) o f s o d i u m b o r o h y d r i d e a d d e d p o r t i o n b y p o r t i o n w i t h s t i r r i n g u n t i l a c l e a r s o l u t i o n was o b t a i n e d . T h e m i x t u r e w a s s t i r r e d a t 0 ° C f o r a n a d d i t i o n a l 30 m i n , t h e n p o u r e d i n t o 1 0 0 mL o f c o l d a q u e o u s H C l s o l u t i o n ( c o n c e n t r a t i o n 0 . 1 M ) . T h e w h i t e p r e c i p i t a t e w a s f i l t r a t e d , w a s h e d a n d d r i e d i n a i r , g i v i n g 2 . 0 g o f c r u d e 9 5 . T h e s o l i d w a s r e c r y s t a l l i z e d f r o m m e t h a n o l a f f o r d i n g 0 . 4 0 g o f c o l o r l e s s p r i s m s ( y i e l d 2 0 % ) , m . p . , 1 7 4 - 1 7 6 ° C . I R ( K B r ) i / m a x : 3 4 9 9 ( O H ) , 1 7 1 2 ( C = 0 ) , 1 6 3 0 (C=C) , 1 4 7 6 , 1 4 5 9 , 1 4 3 8 , 1 2 9 6 , 7 6 4 , 6 1 6 c m " 1 . XH NMR ( 4 0 0 M H z ) 8: 7 . 5 0 - 7 . 0 0 (m, 8 H , a r o m a t i c H) , 5 . 5 8 ( s , I H , C H ) , 5 . 0 5 ( d , 2 H , J - 6 H z , C H 2 ) , 3 . 7 9 ( s , 3 H , OCH3) , 3 . 7 8 ( s , 3 H , OCH3), 2 . 6 4 ( t , I H , J - 6 H z , D 2 0 e x c h a n g e a b l e , OH) p p m . 1 3 C NMR ( 5 0 MHz) 8: 1 6 8 . 3 6 , 1 6 4 . 3 4 (2 x C=0) , 1 5 1 . 2 5 , 1 4 5 . 7 4 , 1 4 4 . 9 4 , 1 4 3 . 5 8 , 1 2 5 . 3 8 , 1 2 5 . 2 7 , 1 2 3 . 8 0 , 1 2 2 . 3 0 ( v i n y l i c C a n d a r o m a t i c - 215 -C ) , 5 9 . 7 9 ( C H 2 O H ) , 5 7 . 3 8 ( b r i d g e h e a d C ) , 5 2 . 5 9 , 5 2 . 4 5 , 5 0 . 9 6 (2 x C 0 2 C H 3 a n d b r i d g e h e a d CH) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 5 0 ( M + , 3 ) , 318 ( 3 6 ) , 2 9 0 ( 6 0 ) , 262 ( 4 3 ) , 2 3 0 ( 5 4 ) , 2 1 5 ( 5 2 ) , 202 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 1 H 1 8 ° 5 : 3 5 0 . 1 1 5 4 . F o u n d : 350 .1147 . A n a l , c a l c d . f o r C 2 i H 1 8 0 5 : C , 7 1 . 9 9 ; H , 5 . 1 7 . F o u n d : C , 7 1 . 8 2 ; H , 5 . 2 3 . D i m e t h y l 9 , 1 0 - D i h y d r o - 9 - c h l o r o m e t h y l - 9 , 1 0 - e t h e n o a n t h r a c e n e - l l , 1 2 -d i c a r b o x y l a t e ( 9 3 d ) 9 - C h l o r o m e t h y l a n t h r a c e n e ( 2 . 2 7 g , 10 m m o l e s ) , a v a i l a b l e f r o m A l d r i c h , a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( 1 . 6 0 g , 11 m m o l e s ) w e r e m i x e d a n d h e a t e d a t 1 0 0 - 1 1 0 ° C f o r 3 h o u r s . C o l u m n c h r o m a t o g r a p h y o f t h e r e s u l t i n g r e a c t i o n m i x t u r e o n s i l i c a g e l u s i n g 25% e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t g a v e 2 . 0 g ( y i e l d 54%) o f y e l l o w c r y s t a l s . C o l o r l e s s p r i s m s w e r e o b t a i n e d b y r e c r y s t a l l i n g t w i c e f r o m c h l o r o f o r m / m e t h a n o l , m . p . , 1 6 8 - 1 7 0 ° C ( / 3 - f o r m c r y s t a l ) . I R ( K B r ) i / m a x : 1 7 2 9 ( C = 0 ) , 1 6 2 9 ( C - C ) , 1 4 3 3 , 1 3 1 3 , 1 2 8 4 , 1 2 6 9 , 1 2 3 7 , 1 2 1 4 , 1 1 2 2 , 1 0 6 2 , 7 7 5 , 7 5 9 , 7 5 0 , 7 0 6 , 633 c m " 1 . 1 H NMR ( 4 0 0 M H z ) 6: 7 . 6 - 7 . 0 (m, 8 H , a r o m a t i c H ) , 5 . 5 9 ( s , I H , b r i d g e h e a d H ) , 4 . 9 5 ( b r o a d s , 2 H , C H 2 C 1 ) , 3 . 7 8 ( s , 3 H , C 0 2 C H 3 ) , 3 . 8 0 ( s , 3 H , C 0 2 C H 3 ) p p m . 1 3 C NMR ( 5 0 MHz) 5 : 1 6 6 . 9 7 , 1 6 4 . 0 1 (2 x C=0) , 1 4 5 . 6 5 * . 1 4 4 . 2 4 , 1 4 3 . 0 1 , 1 2 5 . 6 1 , 1 2 5 . 1 8 , 1 2 3 . 8 8 , 1 2 2 . 1 1 ( v i n y l i c C a n d a r o m a t i c C ) , 5 6 . 7 2 ( b r i d g e h e a d C ) , 5 2 . 4 9 * , 5 0 . 8 5 (2 x C 0 2 C H 3 a n d b r i d g e h e a d CH) , 4 1 . 5 3 ( C H 2 C 1 ) p p m . - 2 1 6 -* p o s s i b l y two c a r b o n s h e r e . MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 7 0 (M+2, 1 5 ) , 3 6 8 ( M + , 4 6 ) , 308 ( 1 0 0 ) , 215 ( 8 4 ) , 191 ( 5 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 i H 1 7 C 1 0 4 : 3 6 8 . 0 8 1 6 . F o u n d : 3 6 8 . 0 8 1 8 . A n a l , c a l c d . f o r C21H17CIO4: C , 6 8 . 3 9 ; H , 4 . 6 5 ; C l , 9 . 6 1 . F o u n d : C , 6 8 . 3 7 ; H , 4 . 7 9 ; C l , 9 . 4 4 . T h e s t r u c t u r e o f t h i s c o m p o u n d was s u p p o r t e d b y a n X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C21H17CIO4, m o n o c l i n i c , s p a c e g r o u p P2\/c, a = 1 0 . 0 8 6 5 ( 6 ) , b = 1 6 . 2 0 7 ( 1 ) , c •= 1 1 . 2 3 2 9 ( 9 ) A , /3 - 1 0 7 . 6 3 6 ( 6 ) ° , V - 1 7 4 9 . 9 (2 ) A 3 , Z - 4 , D x = 1 . 4 0 0 118 g / m L , R = 0 . 0 4 2 . T h e d e t a i l s w e r e p u b l i s h e d e l s e w h e r e . T h i s c r y s t a l l i n e m a t e r i a l c a n a l s o b e o b t a i n e d i n o t h e r f o r m o f c r y s t a l m o d i f i c a t i o n s ( p o l y m o r p h s ) b y r e c r y s t a l l i z a t i o n f r o m a n a p p r o p r i a t e s o l v e n t . N e e d l e c r y s t a l s w e r e o b t a i n e d f r o m d i e t h y l e t h e r / p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) , m . p . , 1 7 4 - 1 7 6 ° C ( a - f o r m c r y s t a l ) . S p a c e g r o u p P 2 i 2 i 2 i . I R ( K B r ) i / m a x : 1 7 1 8 ( C = 0 ) , 1 6 2 8 ( C = C ) , 1 4 5 7 , 1 4 3 4 , 1 3 1 2 , 1 2 7 1 , 1 2 1 1 , 1 1 1 9 , 1 0 5 6 , 7 5 2 , 6 3 1 c m " 1 . R e c t a n g l e c r y s t a l s ( 7 - f o r m ) w e r e o b t a i n e d f r o m a c e t o n e / h e x a n e , m . p . , 1 6 8 - 1 7 0 ° C ( a t 1 4 0 ' C , t h e c l e a r c r y s t a l s t u r n o p a q u e ) . M o n o c l i n i c , S p a c e g r o u p P 2 ] / c , a = 2 0 . 5 5 0 , b = 1 0 . 5 1 3 , c = 1 7 . 8 1 3 A, /3 = 1 0 8 . 1 1 ° , D x = 1 . 3 3 9 g / m L , R = 0 . 0 5 4 . I R ( K B r ) i / m a x : 1 7 1 8 ( C = 0 ) , 1 6 2 4 ( C = C ) , 1 4 5 9 , 1 2 6 5 , 1 2 3 6 , 1 2 1 3 , 1 0 7 8 , 1 0 5 9 , 7 7 0 , 7 5 5 , 6 2 7 c m " 1 . P r e p a r a t i o n o f N - A c e t y l a l a n i n e 9 - A n t h r y l m e t h y l E s t e r ( 8 9 b ) - 217 ( a ) R a c e m i c 8 9 b T h e r e p o r t e d p r o c e d u r e s f o r p r e p a r a t i o n o f o t h e r s i m i l a r c o m p o u n d s 59 w e r e u s e d h e r e . A s o l u t i o n o f (±)-N - a c e t y l a l a n i n e ( 3 9 2 m g , 3 m m o l e s , S i g m a ) , 9 - c h l o r o m e t h y l a n t h r a c e n e ( 6 8 1 m g , 3 m m o l e s ) a n d t r i e t h y l a m i n e ( 0 . 4 2 mL) i n 7 mL o f a c e t o n i t r i l e w a s r e f l u x e d f o r 5 h r . M o s t o f t h e s o l v e n t w a s r e m o v e d a n d t h e r e s u l t i n g m i x t u r e w a s c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 5 0 - 1 0 0 % e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t ; 8 9 0 mg ( y i e l d 92%) o f y e l l o w s o l i d w a s c o l l e c t e d a f t e r t h e c h r o m a t o g r a p h y . R e c r y s t a l l i z a t i o n o f t h e s o l i d f r o m a c e t o n e a f f o r d e d y e l l o w c r y s t a l s , m . p . , 1 7 0 - 1 7 2 ° C . I R ( K B r ) i / m a x : 1 7 2 9 ( C = 0 ) , 1 6 4 6 , 1 5 4 8 , 1 3 7 2 , 1 2 1 2 , 1 1 5 8 , 8 8 6 , 730 c m " 1 . X H NMR ( 4 0 0 MHz) 6: 8 . 5 5 - 7 . 4 5 ( m , 9 H , a r o m a t i c H ) , 6 . 2 7 , 6 . 1 9 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 6 . 0 2 ( d , I H , J = 7 . 5 H z , NHCOCH3) , 4 . 6 0 ( q u i n t e t , I H , 0 C 0 C H ( C H 3 ) N H ) , 1 . 9 8 ( s , 3 H , NHCOCH3), 1 . 3 1 ( d , 3 H , J = 7 . 5 H z , CHCH3) p p m . 1 3 C NMR (75 MHz) 6": 1 7 3 . 2 8 , 1 6 9 . 5 9 (2 x C - 0 ) , 1 3 1 . 2 3 , 1 3 0 . 9 3 , 1 2 9 . 3 9 , 1 2 9 . 0 8 , 1 2 6 . 7 1 , 1 2 5 . 6 0 , 1 2 5 . 0 8 , 1 2 3 . 6 5 ( a r o m a t i c C ) , 5 9 . 9 1 ( C H 2 0 C 0 ) , 4 8 . 2 3 ( C 0 C H ( C H 3 ) N H ) , 2 3 . 0 0 , 1 8 . 3 4 (2 x C H 3 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 2 1 ( M + , 1 7 ) , 191 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C20H19NO3: 3 2 1 . 1 3 6 5 . F o u n d : 3 2 1 . 1 3 6 5 . A n a l , c a l c d . f o r C 2 O H I Q N 0 3 : C , 7 4 . 7 5 ; H , 5 . 9 6 ; N , 4 . 3 6 . F o u n d : C , 7 4 . 7 7 ; H , 6 . 1 0 ; N , 4 . 2 0 . T h i s r a c e m i c c o m p o u n d w a s a n a l y z e d b y t h e c h i r a i s h i f t r e a g e n t , t r i s [ 3 - ( h e p t a f l u o r o p r o p y l h y d r o x y m e t h y l e n e ) - ( + ) - c a m p h o r a t o l ] e u r o p i u m ( I I I ) d e r i v a t i v e a b b r e v i a t e d a s E u ( h f c ) 3 . - 2 1 8 -( b ) O p t i c a l l y A c t i v e 9 3 b A s o l u t i o n o f ( S ) - ( - ) - N - a c e t y l a l a n i n e (393 m g , 3 m m o l e s ) f r o m S i g m a (99% p u r e ) , 9 - c h l o r o m e t h y l a n t h r a c e n e ( 6 8 1 m g , 3 m m o l e s ) a n d t r i e t h y l a m i n e ( 0 .5 mL) i n 7 mL o f a c e t o n i t r i l e w a s r e f l u x e d f o r 6 h r . U p o n d i l u t i o n w i t h 0 . 0 2 % a q u e o u s s o d i u m b i c a r b o n a t e (100 m l ) , t h e p r o d u c t w a s c o l l e c t e d , w a s h e d a n d d r i e d a t r o o m t e m p e r a t u r e ; 8 8 0 mg ( y i e l d 91%) o f t h e c r u d e p r o d u c t was o b t a i n e d , w h i c h w a s u s e d i n t h e n e x t s t e p w i t h o u t f u r t h e r p u r i f i c a t i o n . P u r e ( S ) - ( - ) - N - a c e t y l a l a n i n e 9-a n t h r y l m e t h y l e s t e r w a s o b t a i n e d b y r e c r y s t a l l i z a t i o n f r o m e t h a n o l a s y e l l o w c r y s t a l s , m . p . , 1 8 0 - 1 8 1 ° C . I R ( K B r ) i / m a x : 3 2 9 4 ( N H ) , 1 7 3 2 ( C = 0 ) , 1 6 4 6 , 1 5 4 6 , 1 1 5 8 , 7 3 1 c m " 1 . ••-H NMR ( 3 0 0 M H z ) S: 8 . 6 0 - 7 . 4 0 (m, 9H, a r o m a t i c H) , 6 . 2 6 , 6 . 1 8 ( t w o d , 2 H , J = 12 H z , CH 2 0 C 0 ) , 6 . 0 0 ( d , I H , J = 7 . 5 H z , NHCOCH3) , 4 . 6 1 ( q u i n t e t , I H , J = 7 . 5 H z , 0 C 0 C H ( C H 3 ) N H ) , 1 . 99 ( s , 3H, NHCOCH3), 1 . 3 1 ( d , 3H, J = 7 . 5 H z , CHCH3) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 321 ( M + , 6 ) , 2 0 8 ( 1 5 ) , 191 ( 6 1 ) 179 ( 2 6 ) , 4 4 (100). E x a c t m a s s c a l c u l a t e d f o r C20H19NO3: 3 2 1 . 1 3 6 5 . F o u n d : 3 2 1 . 1 3 6 4 . A n a l , c a l c d . C20H19NO3: C , 74.74; H , 5 . 9 6 ; N , 4 . 3 6 . F o u n d : C , 74.73; H , 6 . 0 2 ; N , 4 . 3 4 . 90 [a ] r j = - 1 . 0 ° ± 0 . 1 ( c = 3 . 0 , CHCI3). T h i s c o m p o u n d was a n a l y z e d b y t h e c h i r a l s h i f t r e a g e n t , E u ( h f c ) 3 a n d s h o w n t o b e o p t i c a l l y p u r e ( e . e . > 9 9 % ) . P r e p a r a t i o n o f D i m e t h y l 9 - ( a - N - A c e t y l a m i n o - a - m e t h y l ) a c e t o x y m e t h y l - 9 , 1 0 -d i h y d r o - 9 , 1 0 - e t h e n o a n t h r a c e n e - l l , 1 2 - d i c a r b o x y l a t e ( 9 3 b ) - 219 -( a ) R a c e m i c 9 3 b ( ± ) - N - a c e t y l a l a n i n e 9 - a n t h r y l m e t h y l e s t e r ( 8 9 b ) ( 6 4 2 m g , 2 . 0 m m o l e s ) a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( 2 8 4 m g , 2 . 0 m m o l e s ) w e r e h e a t e d a t 1 3 0 ° C f o r 2 h r ; 797 mg ( y i e l d 86%) o f y e l l o w s o l i d w a s i s o l a t e d u p o n p u r i f i c a t i o n b y c o l u m n c h r o m a t o g r a p h y . A w h i t e c r y s t a l l i n e s o l i d w a s o b t a i n e d b y r e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e , m . p . , 1 1 0 -1 1 2 ° C . I R ( K B r ) v m a x : 3 2 5 7 ( N H ) , 1 7 5 2 ( C = 0 ) , 1 7 1 7 ( C = C - C = 0 ) , 1 6 3 8 ( C = C ) , 1 5 4 3 , 1 4 5 9 , 1 2 7 4 , 1 2 2 1 , 1 1 6 2 , 7 6 2 , 631 c m " 1 . % NMR ( 3 0 0 MHz) 6: 7 . 5 - 7 . 0 (m, 8H, a r o m a t i c H ) , 6 . 1 4 ( d , I H , J = 8 H z , N H ) , 5 . 6 5 ( s , I H , b r i d g e h e a d H ) , 5 . 5 8 , 5 . 4 2 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 4 . 7 0 ( q u i n t e t , I H , J = 8 H z , CH(NH ) C H 3 ) , 2 . 8 0 , 3 . 7 9 ( t w o s , 6 H , 2 x CO2CH3), 1 . 9 8 ( s , 3 H , NHCOCH3), 1 . 4 5 ( d , 3 H , J <= 8 H z , 0 C 0 C H (CH 3 )NH) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 6 3 ( M + , 1 0 ) , 3 5 0 ( 5 ) , 318 ( 1 8 ) , 290 ( 3 8 ) , 1 1 4 ( 5 7 ) , 4 4 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 6 H 2 5 N 0 7 : 4 6 3 . 1 6 3 1 . F o u n d : 4 6 3 . 1 6 2 6 . ( b ) O p t i c a l l y A c t i v e 9 3 b ( S ) - ( - ) - N - A c e t y l a l a n i n e 9 - a n t h r y l m e t h y l e s t e r ( 8 9 b ) ( 1 . 8 g , 5 . 6 m m o l e s ) a n d d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e ( 0 . 8 0 g , 5 . 6 m m o l e s ) w e r e m i x e d t o g e t h e r a n d h e a t e d a t 1 2 0 - 1 3 0 ° C f o r 30 m i n . T h e c o o l e d m i x t u r e w a s c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 4 0 - 6 0 % a c e t o n e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t . T h i s a f f o r d e d a n o i l w h i c h was c r y s t a l l i z e d f r o m b e n z e n e . Y e l l o w c r y s t a l s ( 1 . 8 g , y i e l d 6 9 % ) , ( S ) - ( + ) -- 2 2 0 -9 3 b , w e r e o b t a i n e d . F u r t h e r r e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e g a v e c o l o r l e s s c r y s t a l s , m . p . , 1 7 8 - 1 8 0 ° C . I R ( K B r ) » / m a x : 3 4 0 8 (NH) , 1736 (C=0) , 1 7 1 3 ( C = 0 ) , 1 6 7 2 (NHC=0) , 1 6 2 3 ( C = C ) , 1 5 2 7 , 1 4 3 6 , 1 2 5 2 , 1 2 1 7 , 1 1 3 4 , 1 0 6 9 , 1 0 5 1 , 1 0 0 3 , 7 6 2 c m " 1 . "•"H NMR ( 4 0 0 MHz) 6: 7 . 4 5 - 7 . 0 0 ( m , 8H, a r o m a t i c H ) , 6 . 0 7 ( d , I H , J = 8 H z , N H ) , 5 . 6 4 ( s , I H , CH) , 5 . 5 7 , 5 . 4 3 ( t w o d , 2 H , J = 12 H z , C H 2 O C O ) , 4 . 7 0 ( q u i n t e t , I H , J = 8 H z , C O C H ) ) , 3 . 8 9 0 ( s , 3 H , O C H 3 ) , 3 . 8 8 5 ( s , 3 H , OCH3), 1 . 9 6 ( s , 3 H , COCH3), 1 . 4 4 ( d , 3 H , J - 8 H z , CH3) p p m . 1 3 C NMR ( 5 0 MHz) 6: 1 7 2 . 3 8 , 1 6 9 . 9 1 , 1 6 7 . 1 6 , 1 6 3 . 8 0 (4 x C=0 ) , 1 5 0 . 9 5 , 1 4 5 . 3 3 * , 1 4 4 . 1 2 , 1 4 2 . 5 6 , 1 4 2 . 5 1 , 1 2 5 . 7 4 , 1 2 5 . 7 0 , 1 2 5 . 3 7 , 1 2 5 . 3 2 , 1 2 4 . 0 3 , 1 2 3 . 9 8 , 1 2 1 . 7 6 , 1 2 1 . 4 9 ( a r o m a t i c a n d v i n y l i c C ) , 6 1 . 8 0 ( C H 2 0 C 0 ) , 5 4 . 8 8 ( b r i d g e h e a d C ) , 5 2 . 5 9 , 5 2 . 3 4 , 5 0 . 6 7 , 4 8 . 3 3 (2 x C 0 2 C H 3 , b r i d g e h e a d CH a n d N H C 0 C H 3 ) , 2 2 . 9 8 , 1 8 . 1 1 ( C 0 C H ( N H ) C H 3 ) p p m . * p o s s i b l y two c a r b o n s h e r e . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 6 3 ( M + , 2 0 ) , 3 5 0 ( 7 ) , 318 ( 2 4 ) , 290 ( 5 7 ) , 262 ( 1 6 ) , 2 3 0 ( 2 1 ) , 215 ( 3 8 ) , 202 ( 3 9 ) , 1 1 4 ( 5 7 ) , 86 ( 5 2 ) , 44 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C ^ H ^ N O y : 4 6 3 . 1 6 3 1 . F o u n d : 4 6 3 . 1 6 2 9 . A n a l , c a l c d . f o r C 2 6 H 2 5 N 0 7 : C , 6 7 . 3 8 ; H , 5 . 4 4 ; N , 3 . 0 2 . F o u n d : C , 6 7 . 6 7 ; H , 5 . 5 3 ; N , 3 . 0 4 . [ a ] D 2 0 - + 0 . 4 ° ± 0 . 1 ( c = 3 . 0 , CHCI3). A l s o [ a ] 2 0 3 6 5 n m = - 3 3 . 3 ° ± 0 . 1 ( c = 3 . 0 , CHCI3). T h i s c o m p o u n d was a g a i n a n a l y z e d b y t h e c h i r a i s h i f t r e a g e n t , E u ( h f c ) 3 , a n d s h o w n t o b e o p t i c a l l y p u r e ( e . e . > 9 9 % ) . T h e s t r u c t u r e o f t h i s c o m p o u n d was a l s o c o n f i r m e d b y a n X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C 2 g H 2 5 N 0 7 , o r t h o r h o m b i c , s p a c e g r o u p P 2 i 2 i _ 2 ] _ , a = 1 8 . 9 1 4 ( 4 ) , b = 1 4 . 3 4 5 ( 1 ) , c = 221 -8 . 6 2 2 (1)A, V = 2 3 3 9 . 5 (5 )A 3 , Z - 4 , D x = 1 . 3 2 g / m L , R = 0 . 0 3 8 . T h e d e t a i l s w i l l b e p u b l i s h e d e l s e w h e r e . 9-Anthrylmethyl a-Methoxy Benzeneacetate (89a) (a) (±)-89a A s o l u t i o n o f 6 8 0 mg ( 3 . 0 m m o l e s ) o f 9 - c h l o r o m e t h y l a n t h r a c e n e , 4 9 8 mg ( 3 . 0 m m o l e s ) o f ( ± ) - a - m e t h o x y b e n z e n e a c e t i c a c i d ( A l d r i c h ) a n d 0 . 5 mL o f t r i e t h y l a m i n e i n 5 mL o f a c e t o n i t r i l e was r e f l u x e d f o r 5 h o u r s . T h e s o l u t i o n w a s d i l u t e d w i t h 50 mL o f 0 . 0 4 % a q u e o u s s o d i u m b i c a r b o n a t e . T h e r e s u l t i n g y e l l o w s o l i d was c o l l e c t e d , w a s h e d w i t h w a t e r a n d d r i e d i n a i r , a f f o r d i n g 1 . 0 g ( y i e l d 9 4 % ) . R e c r y s t a l l i z a t i o n f r o m e t h a n o l g a v e o r a n g e f l a k e s , m . p . , 1 2 2 - 1 2 4 ° C . IR ( K B r ) i /max: 1 7 3 4 ( C = 0 ) , 1 4 5 5 , 1 2 7 5 , 1 1 9 8 , 1 1 7 6 , 1 1 5 7 , 1 1 2 1 , 1 0 5 9 , 9 9 8 , 9 2 6 , 9 1 4 , 8 8 0 , 7 2 8 , 6 9 5 , 629 c m " 1 . 1 H NMR ( 3 0 0 MHz) 6 : 8 . 6 - 7 . 2 (m, 1 4 H , a r o m a t i c H ) , 6 . 3 0 , 6 . 0 0 ( t w o d , 2 H , J - 12 H z , C H 2 0 C 0 ) , 4 . 7 6 ( s , I H , C 0 C H ( 0 C H 3 ) P h ) , 3 . 3 8 ( s / 3 H , OCH3) p p m . 1 3 C NMR ( 7 5 MHz) 5 : 1 7 1 . 0 3 ( C - 0 ) , 1 3 6 . 0 0 , 1 3 1 . 2 3 , 1 3 0 . 9 7 , 1 2 9 . 3 0 , 1 2 9 . 0 0 , 1 2 8 . 6 5 , 1 2 8 , 5 5 , 1 2 7 . 1 2 , 1 2 6 . 5 7 , 1 2 5 . 7 1 , 1 2 5 . 4 5 , 1 2 5 . 0 3 , 1 2 3 . 7 2 ( a r o m a t i c C ) , 8 2 . 3 9 ( A r C H 2 0 C 0 ) , 5 9 . 7 5 (OCH3), 5 7 . 3 3 ( C H ( 0 C H 3 ) P h ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 356 ( M + , 1 2 ) , 1 9 1 ( 8 4 ) , 1 2 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r £ 2 4 ^ 2 0 ^ 3 : 3 5 6 . 1 4 1 3 . F o u n d : 3 5 6 . 1 4 1 4 . A n a l , c a l c d . f o r C 2 4 H 2 ( ) 0 3 : C , 8 0 . 8 8 ; H , 5 . 6 6 . F o u n d : C , 8 0 . 9 6 ; H , 5 . 6 2 . - 222 -( b ) ( R ) - ( - ) - 8 9 a T h e same p r o c e d u r e s a s d e s c r i b e d i n t h e a b o v e c a s e w e r e f o l l o w e d . A s o l u t i o n o f 6 8 0 mg ( 3 . 0 m m o l e s ) o f 9 - c h l o r o m e t h y l a n t h r a c e n e , 500 mg ( 3 . 0 m m o l e s ) o f ( R ) - ( - ) - a - m e t h o x y b e n z e n e a c e t i c a c i d ( A l d r i c h ) a n d 0 . 5 mL o f t r i e t h y l a m i n e w a s r e f l u x e d f o r 5 h o u r s ; 1 . 0 g ( y i e l d 94%) o f t h e p r o d u c t w a s i s o l a t e d a s y e l l o w s o l i d a f t e r w o r k - u p . R e c r y s t a l l i z a t i o n f r o m e t h a n o l a f f o r d e d t h i n f l a k e s , m . p . 1 4 5 - 1 4 7 ° C . I R ( K B r ) i / m a x : 1 7 3 4 ( C = 0 ) , 1 1 9 8 , 1 1 7 5 , 1 1 2 1 , ' 9 9 7 , 9 2 6 , 8 8 0 , 7 2 8 , 628 c m " 1 . % NMR ( 3 0 0 MHz) 5 : 8 . 5 5 - 7 . 2 5 ( m , 1 4 H , a r o m a t i c H) , 6 . 9 9 , 6 . 3 0 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 4 . 7 8 ( s , I H , b r i d g e h e a d H ) , 3 . 3 8 ( s , I H , OCH3) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 356 ( M + , 1 2 ) , 1 9 1 ( 8 3 ) , 1 2 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C24H20O3: 3 5 6 . 1 4 1 3 . F o u n d : 3 5 6 . 1 4 1 6 . A n a l , c a l c d . f o r C24H20O3: C , 8 0 . 8 8 ; H , 5 . 6 6 . F o u n d : C , 8 0 . 8 5 ; H , 5 . 6 5 . [ a ] D 2 0 = - 6 9 ° ± 0 . 1 ( c - 3 . 0 , CHCI3). D i m e t h y l 9 - ( a - M e t h o x y - a - p h e n y l ) a c e t o x y m e t h y l - 9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o -a n t h r a c e n e - 1 1 , 1 2 - d i c a r b o x y l a t e ( 9 3 a ) ( a ) ( ± ) - 9 3 a A m i x t u r e o f 1 . 2 g ( 3 . 4 m m o l e s ) o f ( ± ) - 9 - a n t h r y l m e t h y l a - m e t h o x y b e n z e n e a c e t a t e , ( ( ± ) - 8 9 a ) , a n d 0 . 5 0 g ( 3 . 5 m m o l e s ) o f d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e was h e a t e d a t 1 3 0 ° C f o r 2 h o u r s . C h r o m a t o g r a p h y o f t h e r e a c t i o n m i x t u r e o n s i l i c a g e l b y u s i n g 30% e t h y l a c e t a t e i n 223 -p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t a f f o r d e d 7 7 0 mg ( y i e l d 45%) o f a n o i l w h i c h w a s c r y s t a l l i z e d f r o m e t h a n o l . R e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e t w i c e g a v e c o l o r l e s s p r i s m s , m . p . , 1 4 1 - 1 4 2 ° C . I R ( K B r ) i / m a x : 1 7 5 3 ( C = 0 ) , 1 7 1 7 ( C = C - C = 0 ) , 1 6 3 0 ( C = C ) , 1 4 5 8 , 1 4 3 3 , 1 3 2 6 , 1 2 8 0 , 1 2 4 2 , 1 2 1 2 , 1 1 8 0 , 1 0 2 0 , 7 4 4 c m " 1 . L H NMR ( 3 0 0 M H z ) 6: 7 . 5 0 - 6 . 7 0 (m, 1 3 H , a r o m a t i c H ) , 5 . 6 1 ( s , I H , b r i d g e h e a d H ) , 5 . 6 3 , 5 . 2 2 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 4 . 7 8 ( s , I H , C H ( 0 C H 3 ) P h ) , 3 . 7 9 ( s , 3 H , C 0 2 C H 3 ) , 3 . 7 1 ( s , 3 H , C 0 2 C H 3 ) , 3 . 4 5 ( s , 3 H , C H ( 0 C H 3 ) P h ) p p m . 1 3 C NMR ( 7 5 MHz) 6: 1 7 0 . 3 4 , 1 6 6 . 6 7 , 1 6 3 . 8 3 (3 x C=0) , 1 5 0 . 8 1 , 1 4 5 . 1 9 , 1 4 5 . 0 8 , 1 4 3 . 9 6 , 1 4 2 . 4 2 , 1 4 2 . 3 0 , 1 3 5 . 5 0 , 1 2 8 . 9 1 , 1 2 8 . 7 2 , 1 2 7 . 4 8 , 1 2 5 . 5 3 , 1 2 5 . 3 4 , 1 2 5 . 2 0 , 1 2 5 . 0 9 , 1 2 3 . 8 7 , 1 2 3 . 6 7 , 1 2 1 . 9 6 , 1 2 1 . 3 6 ( a r o m a t i c a n d v i n y l i c C ) , 8 2 . 1 9 ( 0 2 C C H ( O C H 3 ) P h ) , 6 1 . 5 4 ( C H 2 0 C 0 ) , 5 7 . 3 6 , 5 2 . 4 6 , 5 2 . 3 0 , 5 0 . 5 8 (2 x C 0 2 C H 3 , C H ( 0 C H 3 ) P h a n d b r i d g e h e a d C H ) , 5 4 . 5 9 ( b r i d g e h e a d C) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 9 8 ( M + , 4 ) , 1 2 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 3 0 H 2 6 O 7 : 4 9 8 . 1 6 7 9 . F o u n d : 4 9 8 . 1 6 7 5 . A n a l , c a l c d . f o r C 3 0 H 2 6 0 7 : C , 7 2 . 2 7 ; H , 5 . 2 6 . C , 7 2 . 3 4 ; H , 5 . 3 1 . (b ) ( R ) - ( - ) - 9 3 a A m i x t u r e o f 8 2 0 mg ( 2 . 3 m m o l e s ) o f ( R ) - ( - ) - 9 - a n t h r y l m e t h y l a-m e t h o x y b e n z e n e a c e t a t e ( o p t i c a l l y a c t i v e 8 9 a ) a n d 4 0 0 mg ( 2 . 8 m m o l e s ) o f d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e was h e a t e d a t 1 3 0 " C f o r 30 m i n . T h e r e s u l t i n g m i x t u r e was p u r i f i e d b y c o l u m n c h r o m a t o g r a p h y a f f o r d i n g 245 mg ( y i e l d 21%) o f o p t i c a l l y p u r e s a m p l e , m . p . 1 4 1 - 1 4 3 ° C . 224 IR ( K B r ) i / m a x : 1 7 5 3 ( C - 0 ) , 1 7 1 8 ( C - C - C - O ) , 1 6 3 0 ( C - C ) , 1 4 5 9 , 1 4 3 3 , 1 3 2 7 , 1 2 7 9 , 1 2 4 1 , 1 2 1 2 , 1 1 8 0 , 1 1 1 5 , 1 0 9 3 , 1 0 2 0 , 7 6 9 , 7 4 4 , 6 9 6 , 6 1 7 c m " 1 . 1 H NMR ( 4 0 0 M H z ) 6: 7 . 5 0 - 6 . 7 5 (m , 1 4 H , a r o m a t i c H ) , 5 . 6 0 ( s , I H , b r i d g e h e a d H) , 5 . 6 2 , 5 . 2 4 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 4 . 7 8 ( s , I H , C 0 C H ( 0 C H 3 ) P h ) , 3 . 7 8 ( s , 3 H , C 0 2 C H 3 ) , 3 . 7 2 ( s , 3 H , C 0 2 C H 3 ) , 3 . 4 6 ( s , 3 H , C H ( 0 C H 3 ) P h ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 9 8 ( M + , 1 ) , 215 ( 5 ) , 1 2 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 3 Q H 2 6 0 7 : 4 9 8 . 1 6 7 8 . F o u n d : 4 9 8 . 1 6 7 6 . A n a l , c a l c d . f o r C 3 0 H 2 6 O 7 : C , 7 2 . 2 7 ; H , 5 . 2 6 . F o u n d : C , 7 2 . 2 2 ; H, 5 . 2 5 . [ a ] D 2 0 = - 4 . 0 ° ± 0 . 1 ( c = 1 . 0 , C H C 1 3 ) . M e t h y l 9 - ( a - M e t h o x y - a - p h e n y l ) a c e t o x y m e t h y l - 9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o -a n t h r a c e n e - l l - c a r b o x y l a t e (99) a n d M e t h y l 9 - ( a - M e t h o x y - a - p h e n y l ) -a c e t o x y m e t h y l - 9 , 1 0 - d i h y d r o - 9 , 1 0 - e t h e n o a n t h r a c e n e - 1 2 - c a r b o x y l a t e ( 1 0 0 ) . ( D i e l s - A l d e r R e a c t i o n o f 9 - A n t h r y l m e t h y l a - M e t h o x y B e n z e n e a c e t a t e a n d M e t h y l P r o p y n o a t e ) ( a ) (±)-99 a n d ( ± ) - 1 0 0 A m i x t u r e o f 1 . 7 g ( 4 . 8 m m o l e s ) o f ( ± ) - 9 - a n t h r y I m e t h y l a - m e t h o x y l b e n z e n e a c e t a t e a n d 1 . 0 g (12 m m o l e s ) o f m e t h y l p r o p y n o a t e i n a s e a l e d t u b e was k e p t a t 1 5 0 ° C f o r 8 h o u r s . T h e r e s u l t i n g b r o w n gum was c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 20% e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t . Two i s o m e r i c D i e l s - A l d e r a d d u c t s w e r e c r y s t a l l i z e d o u t f r o m t h e s e p a r a t e d f r a c t i o n s ; 330 mg ( y i e l d 13%) o f (±)-99 w e r e o b t a i n e d a n d 210 mg ( y i e l d 8%) of t h e o t h e r i s o m e r , i . e . 225 ( ± ) - 1 0 0 , w e r e i s o l a t e d . C h a r a c t e r i z a t i o n o f t h e two i s o m e r s w a s a s f o l l o w s . ( i ) C h a r a c t e r i z a t i o n o f ( ± ) - 9 9 m . p . 1 9 3 . 5 - 1 9 5 ° C . I R ( K B r ) i / m a x : 1 7 5 2 ( C = 0 ) , 1 7 1 5 ( C = C - C = 0 ) , 1 6 1 5 ( C = C ) , 1 4 5 9 , 1 4 3 5 , 1 3 2 8 , 1 3 1 5 , 1 2 9 6 , 1 2 6 0 , 1 2 1 5 , 1 1 7 6 , 1 1 2 6 , 1 1 1 4 , 1 0 4 5 , 1 0 1 6 , 7 6 7 , 7 5 7 , 7 3 4 , 586 c m " 1 . X H NMR ( 4 0 0 MHz) 5 : 7 . 8 7 ( d , I H , J = 6 H z , v i n y l i c H) , 7 . 4 5 - 6 . 8 0 (m, 1 3 H , a r o m a t i c H ), 5 . 8 7 , 5 . 5 0 ( t w o b r o a d s , 2 H , C H 2 0 C 0 ) , 5 . 1 5 ( d , IH J = 6 H z , b r i d g e h e a d H ) , 4 . 7 7 ( s , I H , C 0 C H ( 0 C H 3 ) P h ) , 3 . 5 1 ( b r o a d s , 3 H , C 0 2 C H 3 ) , 3 . 4 5 ( s , 3 H , C H ( 0 C H 3 ) P h ) p p m . 1 3 C NMR ( 7 5 MHz) 6: 1 7 0 . 5 3 , 1 6 5 . 5 0 (2 x C=0) , 1 5 1 . 4 4 , 1 4 5 . 1 3 , 1 4 4 . 1 8 , 1 4 4 . 1 0 , 1 4 3 . 0 7 , 1 3 5 . 8 3 , 1 2 8 . 7 3 , 1 2 8 . 6 0 , 1 2 7 . 4 2 , 1 2 4 . 9 7 , 1 2 4 . 9 3 , 1 2 4 . 8 9 , 1 2 4 . 8 5 , 1 2 3 . 4 9 , 1 2 3 . 4 5 , 1 2 1 . 9 4 ( a r o m a t i c a n d v i n y l i c C ) , 8 2 . 3 7 ( 0 2 C C H ( O C H 3 ) P h ) , 6 2 . 4 0 ( C H 2 0 C 0 ) , 5 7 . 3 3 , 5 1 . 5 2 , 5 0 . 9 1 ( C 0 2 C H 3 , C H ( 0 C H 3 ) P h a n d b r i d g e h e a d C H ) , 5 3 . 9 ( q u a t e r n a r y C ) ppm MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 4 0 ( M + , 7 ) , 215 ( 2 0 ) , 1 2 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r ^ 3 ^ 4 0 5 : 4 4 0 . 1 6 2 4 . F o u n d : 4 4 0 . 1 6 2 1 . A n a l , c a l c d . f o r C 2 8 H 2 4 0 5 : C , 7 6 . 3 5 ; H , 5 . 4 9 . F o u n d : C , 7 6 . 4 8 ; H , 5 . 5 2 . ( i i ) C h a r a c t e r i z a t i o n o f ( ± ) - 1 0 0 m . p . 1 3 7 - 1 3 9 ° C . I R ( K B r ) v m a x : 1758 ( C = 0 ) , 1708 ( C = C - C = 0 ) , 1 6 2 0 ( C = C ) , 1 4 5 5 , 1 4 3 7 , 1 3 3 1 , 1 3 0 2 , 1 2 2 9 , 1 2 0 5 , 1 1 7 8 , 1 1 5 2 , 1 1 1 2 , 1 0 7 4 , 1 0 5 8 , 1 0 1 4 , 9 9 2 , 7 6 6 , 7 4 2 , 6 9 7 , 580 c m " 1 . 226 L H NMR ( 3 0 0 MHz) 8: 7 . 5 2 ( d , I H , J = 1 H z , v i n y l i c H ) , 7 . 5 0 - 6 . 8 0 ( m , 1 3 H , a r o m a t i c H) , 5 . 6 1 ( d , I H , J = 1 H z , b r i d g e h e a d H) , 5 . 4 3 , 5 . 2 4 ( t w o d , 2 H , J = 12 H z , C H 2 O C O ) , 4 . 9 0 ( s , I H , C 0 C H ( 0 C H 3 ) P h ) , 3 . 7 5 ( s , 3 H , C 0 2 C H 3 ) , 3 . 4 8 ( s , 3 H , C H ( O C H 3 ) P h ) p p m . 1 3 C NMR (75 MHz) 5: 1 7 0 . 9 6 , 1 6 4 . 7 3 (2 x C - 0 ) , 1 4 8 . 7 9 , 1 4 6 . 1 5 , 1 4 6 . 0 0 , 1 4 5 . 4 0 , 1 4 3 . 2 8 , 1 4 3 . 2 2 , 1 3 5 . 6 8 , 1 2 8 . 8 7 , 1 2 8 . 7 0 , 1 2 7 . 2 9 , 1 2 5 . 1 3 , 1 2 5 . 0 1 , 1 2 4 . 7 8 , 1 2 4 . 7 3 , 1 2 3 . 7 1 , 1 2 3 . 6 3 , 1 2 1 . 3 1 , 1 2 1 . 1 2 ( a r o m a t i c a n d v i n y l i c C ) , 8 2 . 2 3 ( 0 2 C C H ( O C H 3 ) P h ) , 6 3 . 0 2 ( C H 2 O C O ) , 5 7 . 3 1 , 5 1 . 8 7 , 5 0 . 2 7 ( C 0 2 C H 3 , C H ( 0 C H 3 ) P h a n d b r i d g e h e a d C H ) , 5 3 . 7 7 ( b r i d g e h e a d C ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 4 0 ( M + , 2 ) , 215 ( 1 9 ) , 121 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C28H24O5: 4 4 0 . 1 6 2 4 . F o u n d : 4 4 0 . 1 6 2 5 . A n a l , c a l c d . f o r C 2 8 H 2 4 0 5 : C , 7 6 . 3 5 ; H , 5 . 4 9 . F o u n d : C , 7 6 . 4 8 ; H , 5 . 5 8 . ( b ) ( R ) - ( - ) - 9 9 a n d ( R ) - ( - ) - 1 0 0 ( R ) - (- ) - 9 - A n t h r y l m e t h y l o ; - m e t h o x y l b e n z e n e a c e t a t e ( 8 8 0 m g , 2 . 5 m m o l e s ) a n d m e t h y l p r o p y n o a t e ( 1 . 0 g , 12 m m o l e s ) i n a s e a l e d t u b e w e r e h e a t e d a t 1 5 0 ° C f o r 10 h o u r s . T h e f i r s t c o l u m n o n s i l i c a g e l , u s i n g 20% e t h y l a c e t a t e i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t , s e p a r a t e d t h e p r o d u c t s f r o m t h e r e a c t i o n m i x t u r e . F u r t h e r p u r i f i c a t i o n b y a s e c o n d c o l u m n o n s i l i c a g e l b y u s i n g 20% d i e t h y l e t h e r i n p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t r e s u l t e d i n 159 mg ( y i e l d 14%) o f ( R ) - ( - ) - 9 9 a n d 99 mg ( y i e l d 8%) o f ( R ) - ( - ) - 1 0 0 . S p e c t r o s c o p i c d a t a o f t h e two i s o m e r s a r e l i s t e d b e l o w . ( i ) C h a r a c t e r i z a t i o n o f ( R ) - ( - ) - 9 9 m . p . 1 8 2 - 1 8 3 ° C . 227 I R ( K B r ) i / r a a x : 1752 ( C = 0 ) , 1 7 1 6 ( C = C - C = 0 ) , 1 6 1 5 ( C = C ) , 1 4 5 8 , 1 3 1 5 , 1 2 9 5 , 1 2 6 0 , 1 2 1 6 , 1 1 7 7 , 7 6 6 , 738 c m " 1 . 1 H NMR ( 3 0 0 MHz) 5 : 7 . 8 8 ( d , I H , J = 6 H z , v i n y l i c H) , 7 . 6 0 - 6 . 8 0 (m, 1 3 H , a r o m a t i c H ) , 5 . 8 7 , 5 . 5 0 ( t w o b r o a d s , 2 H , C H 2 O C O ) , 5 . 1 7 ( d , I H J = 6 H z , b r i d g e h e a d H), 4 . 78 ( s , I H , C O C H ( O C H 3 ) P h ) , 3 . 5 2 ( b r o a d s , 3 H , CO2CH3), 3 . 4 6 ( s , 3 H , C H ( 0 C H 3 ) P h ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 4 0 ( M + , 3 ) , 215 ( 1 4 ) , 121 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 8 H 2 4 ° 5 : 4 4 0 . 1 6 2 4 . F o u n d : 4 4 0 . 1 6 3 3 . A n a l , c a l c d . f o r C 2 8 H 2 4 0 5 : C , 7 6 . 3 5 ; H, 5 .49. F o u n d : C , 7 6 . 3 1 ; H, 5 . 5 1 . [ a ] D 2 ° - - 4 4 ° ± 0 . 1 ( c = 1 , CHCI3). ( i i ) C h a r a c t e r i z a t i o n o f ( R ) - ( - ) - 1 0 0 m . p . 1 5 6 - 1 5 8 ° C . I R ( K B r ) i / m a x : 1759 ( C = 0 ) , 1 7 0 8 ( C = C - C = 0 ) , 1 6 2 8 ( C = C ) , 1 4 5 5 , 1 3 3 1 , 1 2 2 9 , 1 2 0 6 , 1 1 7 8 , 1 1 5 1 , 1 1 1 4 , 1 0 7 4 , 7 6 7 , 741 c m " 1 . 1 H NMR ( 3 0 0 MHz) 5 : 7 . 5 2 ( d , I H , J = 1 Hz, v i n y l i c H) , 7 . 5 0 - 6 . 8 0 (m, 1 3 H , a r o m a t i c H) , 5 . 6 2 ( d , I H , J = 1 H z , b r i d g e h e a d H) , 5 . 4 4 , 5 . 2 5 ( t w o d , 2 H , J = 12 H z , C H 2 0 C 0 ) , 4 . 9 0 ( s , I H , C 0 C H ( 0 C H 3 ) P h ) , 3 . 7 5 ( s , 3 H , C 0 2 C H 3 ) , 3 . 4 8 ( s , 3 H , C H ( 0 C H 3 ) P h ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 4 4 0 ( M + , 0 . 3 ) , 215 ( 1 8 ) , 121 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 3 H 2 4 0 5 : 4 4 0 . 1 6 2 4 . F o u n d : 4 4 0 . 1 6 2 6 . A n a l , c a l c d . f o r C28H24O5: C , 7 6 . 3 5 ; H, 5 . 4 9 . F o u n d : C , 7 6 . 1 9 ; H, 5 . 5 0 . [ a ] D 2 0 = - 4 5 ° ± 0 . 1 ( c = 1 , CHCI3). 228 I I I . P h o t o c h e m i c a l S t u d i e s A . G e n e r a l P r o c e d u r e s A l l a n a l y t i c a l p h o t o l y s e s , b o t h i n s o l u t i o n a n d i n t h e s o l i d s t a t e , w e r e c a r r i e d o u t b y u s i n g a 4 5 0 W H a n o v i a m e d i u m p r e s s u r e m e r c u r y l a m p a n d / o r a PRA U V - 1 2 n i t r o g e n l a s e r f r o m PRA L a s e r I n c . (A = 3 3 7 . 1 nm) a t r o o m t e m p e r a t u r e u n l e s s o t h e r w i s e s t a t e d . S p e c t r a l g r a d e s o l v e n t s (BDH) w e r e u s e d f o r s o l u t i o n p h a s e p h o t o l y s e s a n d t h e c o n c e n t r a t i o n o f t h e s a m p l e s o l u t i o n was k e p t a t c a . 0 . 0 1 M . T h e s a m p l e s w e r e d e g a s s e d b y t h r e e f r e e z e - p u m p - t h a w c y c l e s a n d s e a l e d w i t h p a r a f f i n f i l m u n d e r a n i t r o g e n a t m o s p h e r e i n e a c h c a s e p r i o r t o i r r a d i a t i o n . P h o t o l y s e s i n t h e s o l i d s t a t e w e r e c o n d u c t e d e i t h e r a s s i n g l e c r y s t a l s i n P y r e x o r q u a r t z t u b e s s e a l e d u n d e r n i t r o g e n o r a s p o w d e r s s a n d w i c h e d b e t w e e n two P y r e x m i c r o s c o p e s l i d e p l a t e s . T h e p h o t o l y z e d s a m p l e s w e r e n o r m a l l y a n a l y z e d b y G C , G C - M S , I R a n d 1 H NMR. F o r p r e p a r a t i v e s c a l e p h o t o l y s e s i n s o l u t i o n , 0 . 1 g t o 2 . 0 g o f t h e a p p r o p r i a t e c o m p o u n d was d i s s o l v e d i n 250 mL o f s p e c t r a l g r a d e 89 s o l v e n t a n d p u t i n t o a p r e p a r a t i v e p h o t o l y s i s a p p a r a t u s . T h e s o l u t i o n w a s p u r g e d o f o x y g e n b y p a s s i n g t h r o u g h a s t e a d y f l o w o f n i t r o g e n f o r 60 m i n b e f o r e a n d d u r i n g t h e w h o l e i r r a d i a t i o n p e r i o d . T h e l i g h t s o u r c e u s e d was a 4 5 0 W H a n o v i a m e d i u m p r e s s u r e m e r c u r y l a m p a n d t h e d e s i r e d o u t p u t w a v e l e n g t h was a c h i e v e d b y u s i n g e i t h e r a P y r e x g l a s s f i l t e r (A > 2 9 0 nm) o r a u r a n i u m g l a s s f i l t e r (A > 3 4 0 nm) . T h e p h o t o l y s e s w e r e m o n i t o r e d a n d a n a l y z e d b y GC a n d s t o p p e d w h e n 90% o r h i g h e r o f t h e s t a r t i n g m a t e r i a l was c o n v e r t e d i n t o p h o t o p r o d u c t s . T h e s o l v e n t was r e m o v e d b y e v a p o r a t i o n i n v a c u u m a n d t h e r e s u l t i n g p h o t o l y s a t e was - 229 s u b j e c t e d t o c o l u m n c h r o m a t o g r a p h y . S o l i d s t a t e p h o t o l y s e s o n a p r e p a r a t i v e s c a l e w e r e p e r f o r m e d b y u s i n g p o w d e r e d c r y s t a l s ( 0 . 5 g t o 2 . 0 g ) b e t w e e n two P y r e x g l a s s p l a t e s . T h e p l a t e s w e r e p l a c e d n e a r t h e l i g h t s o u r c e ( 5 - 1 0 cm a w a y ) a n d i r r a d i a t e d a t r o o m t e m p e r a t u r e f o r a p e r i o d o f t i m e u n t i l n o f u r t h e r c o n v e r s i o n o f t h e s t a r t i n g m a t e r i a l w a s o b s e r v e d b y G C . A f t e r t h e p h o t o l y s i s , t h e s o l i d s w e r e s c r a p e d o f f t h e g l a s s p l a t e s a n d s u b j e c t e d t o c o l u m n c h r o m a t o g r a p h y . T h e p h o t o p r o d u c t s w e r e s e p a r a t e d ( o r p a r t i a l l y s e p a r a t e d ) b y c o l u m n c h r o m a t o g r a p h y a n d f u r t h e r p u r i f i e d b y r e c r y s t a l l i z a t i o n i n t h e c a s e o f s o l i d s a m p l e s . Low t e m p e r a t u r e p h o t o l y s e s w e r e c a r r i e d o u t b y m a i n t a i n i n g t h e s a m p l e i n a c o o l i n g b a t h c o n t r o l l e d b y t h e C r y o c o o l C C - 1 0 0 - I I i m m e r s i o n c o o l i n g s y s t e m f r o m N e s l a b I n s t r u m e n t s I n c . T h e t e m p e r a t u r e w a s k e p t w i t h i n ± 1 ° C a n d t h e s a m p l e s w e r e i r r a d i a t e d w i t h t h e H a n o v i a m e d i u m p r e s s u r e m e r c u r y l a m p o r t h e n i t r o g e n l a s e r . B . P h o t o c h e m i s t r y o f S u b s t r a t e s 1 . C y c l o h e x e n o n e D e r i v a t i v e s P h o t o c h e m i c a l S t u d i e s o n 4 - P h e n y l - 4 - p - b r o m o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 a ) I n S o l u t i o n A n a l y t i c a l p h o t o l y s e s w e r e p e r f o r m e d i n a c e t o n e , a c e t o n i t r i l e a n d b e n z e n e . T h e r e a c t i o n s w e r e a n a l y z e d b y G C ( D B - 1 , o v e n t e m p . = 1 9 0 ° C ) 230 -which showed two peaks corresponding to the photoproducts. The r a t i o of the two was constant i n a l l three of the solvents. In a preparative run, a s o l u t i o n of 500 mg of 4-phenyl-4-p-bromophenyl-2-cyclohexen-l-one (71a) i n 250 mL of benzene was i r r a d i a t e d for 20 hours u n t i l more than 99% of the s t a r t i n g material was consumed. A uranium glass f i l t e r was used for A > 340 nm. This l i m i t e d the secondary photoreaction to a n e g l i g i b l e amount. Removal of benzene i n vacuum l e f t a l i g h t o i l . Part of t h i s o i l (250 mg) was chromatographed on s i l i c a gel by using 5-10% d i e t h y l ether/petroleum ether (30-60°) a s the e l u t i n g solvent. The f i r s t column afforded 55 mg of Crans-5-phenyl-6-p-bromophenylbicyclo[3.1.0.]hexan-2-one (72a) and a 1:1 mixture of trans-5-phenyl-6-p-bromophenylbicyclo[3.1.0.]hexan-2-one (72a) and trans-5-p-bromophenyl-6-phenylbicyclo[3.1.0.]hexan-2-one (73a). Chromatographing a second time gave pure trans-5-p-bromophenyl-6-phenylbicyclo[3.1.0.]hexan-2-one (73a). T o t a l y i e l d s were a s follows: 135 mg ( y i e l d 54%) of 72a; 40 mg ( y i e l d 14%) of 73a and 70 mg of a mixture of the two. Characterization of trans-5-Phenyl-6-p-bromophenylbicyclo[3.1.0.]hexan-2-one (72a) This compound was r e c r y s t a l l i z e d from ether/petroleum ether (30-60°) a f t e r the chromatography to a f f o r d c o l o r l e s s prisms, m.p., 93-95°C IR (KBr) i / m a x : 1724 (C-0), 1603, 1489, 919, 823, 763, 699 cm"1. lH NMR (400 MHz) 5: 7.5-7.2 (m, 9H, aromatic H), 3.03 (d, IH, J = 10 Hz, cyclopropyl CH), 2.69 (d, IH, J = 10 Hz, cyclopropyl CH), 2.38 (m, 2H, COCH2CH 2), 2.05-2.20, 1.22-1.10 (m, 2H, COCH2CH2) ppm. - 231 -•^C NMR ( 5 0 MHz) 6 : 2 1 2 . 6 ( C = 0 ) , 1 4 2 . 5 0 , 1 3 3 . 9 2 , 1 3 2 . 0 6 , 1 3 0 . 9 7 , 1 2 8 . 8 4 , 1 2 7 . 2 3 , 1 2 6 . 9 8 , 1 2 1 . 4 8 ( a r o m a t i c C ) , 4 3 . 2 1 ( q u a t e r n a r y C ) , 4 0 . 9 5 , 3 5 . 7 6 ( c y c l o p r o p y l C H C H ) , 3 6 . 4 6 , 2 7 . 0 5 ( C O C H 2 C H 2 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 328 (M+2, 6 ) , 3 2 6 ( M + , 6 ) , 2 8 6 ( 2 4 ) , 2 8 4 ( 2 8 ) , 205 ( 1 0 0 ) , 91 ( 3 1 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 8 H 1 5 B r O : 3 2 6 . 0 3 0 6 . F o u n d : 3 2 6 . 0 3 0 7 . A n a l , c a l c d . f o r CisHlsBrO: C, 6 6 . 0 7 ; H , 4 . 6 2 ; B r , 2 4 . 4 2 . F o u n d : C, 6 5 . 9 0 ; H , 4 . 6 6 ; B r , 2 4 . 3 5 . T h e s t r u c t u r e o f t h i s c o m p o u n d was c o n f i r m e d b y a n X - r a y d i f f r a c t i o n a n a l y s i s . T h e c r y s t a l d a t a w e r e a s f o l l o w s : C ^ H i ^ B r O , m o n o c l i n i c , s p a c e g r o u p I 2 / a , a = 1 7 . 6 0 7 3 ( 3 9 ) , b = 8 . 2 1 3 3 ( 2 0 ) , c = 1 9 . 9 7 6 3 ( 5 0 ) A , /S = 9 3 . 0 9 ( 3 ) ° , V = 2 8 8 4 . 6 ( 1 2 ) A 3 , Z = 8 , Dx = 1 . 5 0 8 g / m L , R = 0 . 0 4 0 . T h e d e t a i l s w e r e p u b l i s h e d e l s e w h e r e . ^ T h e s t r u c t u r e w a s a l s o s u p p o r t e d b y t h e f o l l o w i n g d e u t e r a t i o n r e a c t i o n a n d t h e t r a n s f o r m a t i o n o f t h i s b r o m o d e r i v a t i v e 7 2 a t o t h e c o r r e s p o n d i n g c y a n o d e r i v a t i v e 7 2 b , w h i c h i s a k n o w n c o m p o u n d . ( a ) D e u t e r a t i o n o f t r a n s - 5 - P h e n y l - 6 - p - b r o m o p h e n y l b i c y c l o [ 3 . 1 . 0 ] -h e x a n - 2 - o n e . A s m a l l p i e c e o f s o d i u m was d i s s o l v e d i n 0 . 5 mL o f CD3OD. Two d r o p s o f t h i s s o l u t i o n w e r e a d d e d t o a s o l u t i o n o f trans-5-phenyl-6-p-b r o m o p h e n y l b i c y c l o [ 3 . 1 . 0 ] h e x a n - 2 - o n e ( 7 2 a ) i n CDCI3. T h e m i x t u r e w a s s h a k e n f o r 5 m i n a t r o o m t e m p e r a t u r e a n d a n a l y z e d b y X H NMR, w h i c h s h o w e d t h a t o n e o f t h e m e t h y l e n e p r o t o n s a d j a c e n t t o t h e c a r b o n y l g r o u p w a s s e l e c t i v e l y d e u t e r a t e d . - 232 LH NMR ( 4 0 0 MHz) 6: 7 . 6 0 - 7 . 2 0 (m, 9 H , a r o m a t i c H ) , 3 . 0 7 ( d , I H , J = 10 H z , c y c l o p r o p y l H ) , 2 . 7 0 ( d , I H , J = 10 H z , c y c l o p r o p y l H ) , 2 . 5 0 -2 . 3 5 ( m , 2 H , COCHDCH2), 1 . 2 5 ( t , I H , J = 7 H z , COCHDCH2) p p m . ( b ) R e a c t i o n o f 7 2 a w i t h C u p r o u s C y a n i d e . A m i x t u r e o f t r a n s - 5 - p h e n y l - 6 - p - b r o m o p h e n y l b i c y c l o [ 3 , 1 0 ] h e x a n - 2 -o n e (6 mg) a n d c u p r o u s c y a n i d e ( 1 0 mg) w a s r e f l u x e d i n 1 mL o f N -m e t h y l p y r r o l i d o n e f o r 2 h o u r s . T h e m i x t u r e w a s p o u r e d i n t o w a t e r . T h e a q u e o u s l a y e r w a s e x t r a c t e d w i t h d i e t h y l e t h e r a n d t h e e t h e r e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m . T h e r e s u l t i n g m i x t u r e was a n a l y z e d b y GC a n d GC -MS, a n d t h e d a t a w e r e c o m p a r e d w i t h t h o s e o f t r a n s - 5 - p h e n y l - 6 - p - c y a n o p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 2 b ) , o n e o f t h e k n o w n p h o t o p r o d u c t s f r o m t h e p h o t o l y s i s o f 4 - p h e n y l - 4 - p -53 c y a n o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 b ) . T h e p r o d u c t f r o m t h i s t r a n s f o r m a t i o n p r o v e d t o b e t h e same a s c o m p o u n d 7 2 b b y m e a n s o f GC r e t e n t i o n t i m e a n d GC-MS d a t a . GC-MS m / e ( r e l a t i v e i n t e n s i t y ) : 273 ( M + , 1 0 ) , 244 ( 1 2 ) , 231 ( 1 0 0 ) , 1 5 3 ( 1 7 ) , 115 ( 3 0 ) , 91 ( 5 7 ) . C h a r a c t e r i z a t i o n o f t r a n s - 5 - p - B r o m o p h e n y l - 6 - p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n -2 - o n e ( 7 3 a ) T h i s c o m p o u n d was r e c r y s t a l l i z e d f r o m d i e t h y l e t h e r / p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) t o g i v e c o l o r l e s s p r i s m s , m . p . , 1 0 1 - 1 0 3 . 5 ° C . I R ( K B r ) i / m a x : 1718 ( C = 0 ) , 1 6 0 2 , 1 4 9 1 , 1 0 7 4 , 8 6 0 , 8 1 4 , 703 c m " 1 . 2 3 3 --41 NMR ( 4 0 0 MHz) 6": 7 . 6 0 - 7 . 2 0 (m, 9 H , a r o m a t i c H) , 3 . 0 8 ( d , IH, J = 10 H z , c y c l o p r o p y l C H ) , 2 . 6 6 ( d , I H , J = 10 H z , c y c l o p r o p y l C H ) , 2 . 3 5 -2 . 1 0 , 1 . 2 5 - 1 . 1 0 (m, 4 H , C 0 C H 2 C H 2 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 328 (M+2, 6 ) , 3 2 6 ( M + , 6 ) , 2 8 6 ( 7 0 ) , 2 8 4 ( 6 0 ) , 2 1 9 ( 4 5 ) , 2 0 5 ( 7 0 ) , 189 ( 6 0 ) , 128 ( 6 5 ) , 1 1 5 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 8 H 1 5 B r O : 3 2 6 . 0 3 0 6 . F o u n d : 3 2 6 . 0 3 0 1 . A n a l , c a l c d . f o r C 1 8 H 1 5 B r O : C , 6 6 . 0 7 ; H , 4 . 6 2 ; B r , 2 4 . 4 2 . F o u n d : C , 6 6 . 2 3 ; H , 4 . 6 5 ; B r , 2 4 . 3 0 . T h e s t r u c t u r e o f t h i s c o m p o u n d was a l s o c o n f i r m e d b y i t s 53 c o n v e r s i o n t o t h e k n o w n c y a n o - s u b s t i t u t e d d e r i v a t i v e 7 3 b . T h e s a m e p r o c e d u r e w a s u s e d a s i n t h e p r e v i o u s c a s e , a n d t h e p r o d u c t w a s a l s o a n a l y z e d a n d c h a r a c t e r i z e d b y GC a n d G C - M S i n t e r m s o f t h e GC r e t e n t i o n t i m e a n d G C - M S d a t a . . T h e d a t a w e r e i n g o o d a g r e e m e n t w i t h t h o s e o f trans-5-p-cyanophenyl-6-phenylbicyclo-[3.1.0.]hexan-2-one ( 7 3 b ) . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 273 ( M + , 5 ) , 2 3 1 ( 1 0 0 ) , 115 ( 6 2 ) , 91 ( 2 5 ) . I n t h e S o l i d S t a t e S i n g l e c r y s t a l s o r c r y s t a l l i n e p o w d e r s o f 4 - p - b r o m o p h e n y l - 4 -p h e n y l - 2 - c y c l o h e x e n - l - o n e w e r e p l a c e d i n . P y r e x p h o t o l y s i s t u b e s . T h e s a m p l e s w e r e i r r a d i a t e d f o r 2 0 - 5 0 h o u r s a t r o o m t e m p e r a t u r e u s i n g t h e H a n o v i a m e d i u m p r e s s u r e m e r c u r y l a m p w i t h a u r a n i u m g l a s s f i l t e r o r t h e n i t r o g e n l a s e r . T h e r e s u l t i n g s o l i d s w e r e a n a l y z e d b y F T I R a n d G C . P h o t o l y s i s o f 4 - P h e n y l - 4 - p - c y a n o p h e n y l - 2 - c y c l o h e x e n - l - o n e ( 7 1 b ) - 2 3 4 -T h e s o l u t i o n p h a s e p h o t o l y s i s d e s c r i b e d b y Z i m m e r m a n et al. was p e r f o r m e d u n d e r t h e same c o n d i t i o n s , a n d t h e r e s u l t s o b t a i n e d w e r e i n a g r e e m e n t w i t h t h o s e r e p o r t e d . H o w e v e r , a s l i g h t m o d i f i c a t i o n was c a r r i e d o u t b y c h a n g i n g t h e P y r e x f i l t e r t o a u r a n i u m g l a s s f i l t e r . T h i s m o d i f i c a t i o n m i n i m i z e d t h e s e c o n d a r y p h o t o r e a c t i o n , i . e . t h e p h o t o p r o d u c t o f c i s - 5 - p h e n y l - 6 - p - c y a n o p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 1 0 3 b ) w a s n o t d e t e c t e d b y GC u n d e r t h e e x p e r i m e n t a l c o n d i t i o n s . T h e p r o d u c t s w e r e a n a l y z e d a n d c h a r a c t e r i z e d b y GC ( C a r b o w a x 20M c o l u m n , o v e n t e m p . = 2 1 5 ° C ) a n d G C - M S a n d lti NMR. C h a r a c t e r i z a t i o n o f P h o t o p r o d u c t s ( a ) t r a n s - 5 - P h e n y l - 6 - p - c y a n o p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 2 b ) GC r e t e n t i o n t i m e ( r . t . ) : 1 4 . 7 m i n . I H NMR ( 3 0 0 MHz) 6": 7 . 7 0 - 7 . 0 0 (m, 9 H , a r o m a t i c H ) , 3 . 1 2 a n d 2 . 7 6 ( t w o d , 2 H , J = 10 H z , c y c l o p r o p y l C H C H ) , 2 . 6 0 - 1 . 0 0 (m, 4 H , C H 2 C H 2 ) p p m . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 273 ( M + , 2 ) , 2 3 1 ( 6 5 ) , 153 ( 2 7 ) , 1 1 5 ( 3 3 ) , 91 ( 1 0 0 ) . ( b ) c i s - 5 - P h e n y l - 6 - p - c y a n o p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 1 0 3 b ) GC r e t e n t i o n t i m e : 1 5 . 4 m i n . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 273 ( M + , 1 5 ) , 2 3 1 ( 9 8 ) , 153 ( 1 5 ) , 1 2 8 ( 3 4 ) , 115 ( 5 5 ) , 91 ( 1 0 0 ) . ( c ) t r a n s - 5 - p - C y a n o p h e n y l - 6 - p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 3 b ) GC r e t e n t i o n t i m e : 1 6 . 9 m i n . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 273 ( M + , 2 ) , 2 3 1 ( 9 1 ) , 154 ( 1 0 ) , 1 2 9 ( 4 0 ) , 115 ( 1 0 0 ) , 91 ( 3 1 ) . 2 3 5 -T h e s o l i d s t a t e p h o t o l y s i s o f t h i s c o m p o u n d w a s c a r r i e d o u t u s i n g e i t h e r c r y s t a l s o r p o w d e r s a t r o o m t e m p e r a t u r e . T h e s a m p l e was p h o t o l y z e d f o r 5 m i n t o 4 h o u r s u s i n g a u r a n i u m f i l t e r , p a r t i a l m e l t i n g w a s o b s e r v e d a t h i g h c o n v e r s i o n s o f t h e s t a r t i n g m a t e r i a l . T h e p r o d u c t s a n d p r o d u c t r a t i o s w e r e a n a l y z e d b y G C . P h o t o c h e m i c a l S t u d i e s o n 4 , 4 - D i p h e n y l - 6 - m e t h y l - 2 - c y c l o h e x e n - l - o n e (74a) I n S o l u t i o n A n a l y t i c a l p h o t o l y s e s i n c o m m o n o r g a n i c s o l v e n t s w e r e c a r r i e d o u t . I n e a c h c a s e , t h e p h o t o l y s a t e w a s a n a l y z e d b y GC ( C a r b o w a x 20M c o l u m n , o v e n t e m p = 2 1 5 ° C ) . I n a p r e p a r a t i v e r u n , 4 , 4 - d i p h e n y l - 6 - m e t h y l - 2 - c y c l o h e x e n - l - o n e ( 6 0 0 mg) was p h o t o l y z e d i n 3 0 0 mL o f b e n z e n e f o r 25 h o u r s u s i n g t h e H a n o v i a l a m p w i t h a u r a n i u m g l a s s f i l t e r u n d e r a n i t r o g e n a t m o s p h e r e . B e n z e n e w a s r e m o v e d i n v a c u u m l e a v i n g 6 0 0 mg o f a n o i l . T h e o i l was c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g d i e t h y l e t h e r a n d p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t t o g i v e 3 2 0 mg ( y i e l d 53%) o f a n o i l w h i c h w a s i d e n t i f i e d t o b e e n d o - 3 - m e t h y l - t r a n s - 5 , 6 - d i p h e n y l b i c y c l o -[ 3 . 1 . 0 . ] h e x a n - 2 - o n e (75a), 4 0 mg ( y i e l d 7%) o f e x o - 3 - m e t h y l - t r a n s - 5 , 6 -d i p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e (76a) a n d c a . 2 0 0 mg o f a m i x t u r e o f t h e two p h o t o p r o d u c t s . C h a r a c t e r i z a t i o n o f endo-3-Methyl-trans-5,6-diphenylbicyclo[3.1.0.]-h e x a n - 2 - o n e (75a) - 236 I R ( n e a t ) i / m a x : 1 7 1 9 ( C = 0 ) , 1 6 0 2 , 1 4 9 6 , 1 4 4 6 , 1 3 1 9 , 7 6 4 , 7 0 0 c m " 1 . 1 H NMR ( 3 0 0 MHz) 6: 7 . 4 5 - 7 . 2 3 (m, 1 0 H , a r o m a t i c H ) , 3 . 0 4 ( d , I H , J = 10 H z , c y c l o p r o p y l C H ) , 2 . 8 0 ( d , I H , J = 10 H z , c y c l o p r o p y l C H ) , 2 . 7 4 -2 . 4 4 , 2 . 0 3 - 1 . 9 4 (m, 3 H , C 0 C H ( C H 3 ) C H 2 ) , 0 . 1 7 ( d , J = 7 H z , C H 3 ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 262 ( M + , 1 5 ) , 2 3 4 ( 1 5 ) , 2 0 6 ( 1 0 0 ) , 1 9 1 ( 2 5 ) , 9 1 ( 3 0 ) . E x a c t m a s s c a l c u l a t e d f o r C i q H i g O : 2 6 2 . 1 3 5 8 . F o u n d : 2 6 2 . 1 3 5 0 . T h e s t r u c t u r e o f t h i s c o m p o u n d was s u p p o r t e d b y t h e f o l l o w i n g e p i m e r i z a t i o n r e a c t i o n . E p i m e r i z a t i o n o f endo-3-Methyl-trans-5,6-diphenylbicyclo[3.1.0]-h e x a n - 2 - o n e ( 7 5 a ) C o m p o u n d 7 5 a (2 mg) was d i s s o l v e d i n 1 . 0 mL o f m e t h a n o l . Two d r o p s o f C H 3 O N a / C H 3 O H ( 4 . 3 M) w e r e a d d e d t o t h e a b o v e s o l u t i o n . T h e r e s u l t i n g m i x t u r e w a s p l a c e d a t r o o m t e m p e r a t u r e a n d a n a l y z e d b y GC u n t i l t h e r a t i o o f 7 5 a : 7 6 a ( 1 7 : 8 3 ) r e m a i n e d c o n s t a n t . C h a r a c t e r i z a t i o n o f exo-3-Methyl-trans-5,6-diphenylbicyclo[3.1.0.]hexan-2 - o n e ( 7 6 a ) I R ( n e a t ) i / m a x : 1 7 1 9 ( C = 0 ) , 1 6 0 3 , 1 4 9 6 , 1 4 4 7 , 1 3 2 0 , 7 6 3 , 7 0 0 c m " 1 . "•"H NMR ( 3 0 0 MHz) 5 : 7 . 4 2 - 7 . 2 5 (m, 1 0 H , a r o m a t i c H) , 3 . 1 3 ( d , I H , J = 10 H z , c y c l o p r o p y l CH) , 2 . 7 5 - 1 . 9 5 (m, 3 H , c y c l o p r o p y l CH a n d C H 2 ) , 1 . 1 2 (m, I H C 0 C H ) , 0 . 9 2 ( d , 3 H , J = 7 H z , C H 3 ) p p m . 1 3 C NMR ( 5 0 MHz) 5 : 2 1 5 . 0 ( C = 0 ) , 1 4 3 . 0 9 , . 1 3 5 . 1 6 , 1 2 9 . 9 2 , 1 2 9 . 3 2 , 1 2 8 . 9 0 , 1 2 8 . 7 7 , 1 2 7 . 3 5 a n d 1 2 7 . 0 4 ( a r o m a t i c C ) , 4 1 . 0 1 , 3 6 . 7 9 ( q u a t e r n a r y C a n d C H 2 ) , 4 0 . 8 2 , 4 0 . 6 2 , 3 7 . 2 6 (3 x C H ) , 1 5 . 1 0 ( C H 3 ) p p m . - 237 MS m / e ( r e l a t i v e i n t e n s i t y ) : 262 ( M + , 2 5 ) , 2 3 4 ( 2 0 ) , 206 ( 1 0 0 ) , 1 9 1 ( 2 5 ) , 91 ( 3 5 ) . E x a c t m a s s c a l c u l a t e d f o r C 1 9 H 1 8 0 : 2 6 2 . 1 3 5 8 . F o u n d : 2 6 2 . 1 3 5 7 . T h e s t r u c t u r e o f t h i s c o m p o u n d w a s a l s o c o n f i r m e d b y t h e f o l l o w i n g i n d e p e n d e n t s y n t h e s i s . M e t h y l a t i o n o f trans-5,6-Diphenylbicyclo[3.1.0.]hexan-2-one. D i i s o p r o p y l a m i n e ( 1 2 5 m g , 1 . 2 m m o l e s ) was d i s s o l v e d i n 10 mL o f a n h y d r o u s T H F . n - B u L i i n h e x a n e (5 m L , c a . 0 . 2 6 M) w a s a d d e d a t - 1 0 ° C . T h e m i x t u r e w a s s t i r r e d a t - 1 0 ° C f o r 15 m i n , t h e n c o o l e d t o - 7 8 ° C . t r a n s - 5 , 6 - D i p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 3 9 ) ( 2 5 0 m g , 1 . 0 m m o l e s ) , w h i c h w a s p r e p a r e d b y D r . O m k a r a m N a l a m a s u a c c o r d i n g t o t h e l i t e r a t u r e , i n 5 mL o f a n h y d r o u s T H F w a s d r o p p e d i n t o t h e a b o v e s o l u t i o n a n d t h e r e s u l t i n g m i x t u r e was s t i r r e d a t - 7 8 ° C f o r 20 m i n . N e x t , 1 . 5 mL o f CH3I ( p a s s e d t h r o u g h b a s i c a l u m i n a ) was a d d e d . T h e s o l u t i o n w a s k e p t s t i r r i n g a t r o o m t e m p e r a t u r e f o r 16 h o u r s , a n d p o u r e d i n t o 1 .5% a q u e o u s NH4CI ( 2 0 mL) . T h e a q u e o u s l a y e r w a s e x t r a c t e d w i t h d i e t h y l e t h e r a n d t h e e t h e r e x t r a c t s w e r e w a s h e d , d r i e d a n d c o n c e n t r a t e d i n v a c u u m l e a v i n g a y e l l o w o i l . A c o l o r l e s s o i l ( 2 1 5 m g , y i e l d 81 %) was o b t a i n e d b y c h r o m a t o g r a p h y o n s i l i c a g e l b y u s i n g d i e t h y l e t h e r / p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t . T h i s m a t e r i a l was p r o v e d t o b e i d e n t i c a l t o e x o - 3 - m e t h y l - t r a n s - 5 , 6 - d i p h e n y l b i c y c l o -[ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 6 a ) b y t h e s p e c t r o s c o p i c m e t h o d s . P h o t o l y s i s o f 7 4 a i n t h e S o l i d S t a t e P h o t o l y s e s i n t h e s o l i d s t a t e b y u s i n g c r y s t a l s o r c r y s t a l l i n e p o w d e r s o f 7 4 a w e r e c a r r i e d o u t a t e i t h e r r o o m o r l o w t e m p e r a t u r e s u n d e r - 238 -the s i m i l a r conditions to that described i n the photolysis of 71a. In a l l cases, the photoproducts were rou t i n e l y analyzed by GC. Photochemical Studies on 4,A-Diphenyl-6-ethyl-2-cyclohexen-l-one (74b) A n a l y t i c a l photolyses were performed i n acetone, a c e t o n i t r i l e and benzene. The reaction mixture was analyzed by GC (Carbowax 20M column, oven temp = 215°C). A preparative photolysis was c a r r i e d out by using 700 mg of 4,4-diphenyl-6-ethyl-2-cyclohexen-l-one i n 300 mL of acetone. The reaction was stopped a f t e r i r r a d i a t i o n f o r 75 hours. GC analysis showed that over 90% of the s t a r t i n g material was consumed. P u r i f i c a t i o n by column chromatography on s i l i c a gel by using d i e t h y l ether/petroleum ether (SO-SO") as the e l u t i n g solvent gave two p a r t i a l l y separated photoproducts which were characterized as follows. endo-3-Ethyl-trans-5,6-diphenylbicyclo[3.1.0.]hexan-2-one (75b) This compound was obtained as an o i l (85% pure). IR (neat) i / m a x : 1719 (C=0), 1603, 1496, 1447, 763, 700 cm"1. XH NMR (400 MHz) 6": 7.45-7.20 (m, 10H, aromatic H), 3.03 (d, IH, J - 10 Hz, cyclopropyl CH), 2.79 (d, IH, J = 10 Hz, cyclopropyl CH), 2.70-2,00 (m, 3H, C0CH(Et)CH 2), 0.58 (t, 3H, J = 7 Hz, CH 2CH 3), 1.05-1.20, -0.10 to -0.22 (m, 2H, CH 2CH 3) ppm. GC-MS m/e ( r e l a t i v e i n t e n s i t y ) : 276 (M +, 2), 248 (8), 219 (21), 206 (100), 191 (23), 91 (45). Exact mass ca l c u l a t e d for C 2 0H 2 0O: 276.1514. Found: 276.1513. 239 e x o - 3 - E t h y l - trans - 5 , 6 - d i p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 6 b ) T h i s m a t e r i a l was a l s o o b t a i n e d a s a n o i l (90% p u r e ) . T h e s p e c t r o s c o p i c d a t a w e r e i n g o o d a g r e e m e n t w i t h t h o s e o b t a i n e d f r o m t h e f o l l o w i n g i n d e p e n d e n t s y n t h e s i s . P r e p a r a t i o n o f C o m p o u n d 7 6 b f r o m A l k y l a t i o n o f t r a n s - 5 , 6 - D i p h e n y l -b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e . n - B u L i i n h e x a n e ( 2 . 1 0 m L , c a . 1 . 1 M) was a d d e d i n t o a s o l u t i o n o f d i i s o p r o p y l a m i n e ( 2 6 0 m g , 2 . 5 7 m m o l e s ) i n 8 mL o f a n h y d r o u s T H F a t - 1 0 ° C . A f t e r 10 m i n s t i r r i n g , t r a n s - 5 , 6 - d i p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 -o n e ( 5 0 0 m g , 2 . 0 1 m m o l e s ) i n 5 mL o f a n h y d r o u s T H F w a s d r o p p e d i n t o t h e a b o v e s o l u t i o n a n d t h e r e s u l t i n g m i x t u r e w a s s t i r r e d a t - 7 8 ° C f o r 20 m i n . E t h y l i o d i d e ( 2 . 0 m L , p u r i f i e d b y p a s s a g e t h r o u g h b a s i c a l u m i n a i n 5 mL o f a n h y d r o u s T H F was t h e n d r o p p e d i n t o t h e a b o v e s o l u t i o n a t - 7 8 ° C . T h e m i x t u r e w a s s t i r r e d a t r o o m t e m p e r a t u r e o v e r n i g h t a n d w o r k u p t h e same a s d e s c r i b e d p r e v i o u s l y ; 4 0 0 mg ( y i e l d 73%) o f e x o - 3 - e t h y l - t r a n s -5 , 6 - d i p h e n y l b i c y c l o [ 3 . 1 . 0 . ] h e x a n - 2 - o n e ( 7 6 b ) w e r e o b t a i n e d a s a c o l o r l e s s o i l w h i c h s o l i d i f i e d o n s t a n d i n g . R e c r y s t a l l i z a t i o n f r o m a c e t o n e / h e x a n e a f f o r d e d c o l o r l e s s p r i s m s , m . p . , 8 7 - 8 9 ° C . I R ( n e a t ) i / m a x : 1 7 1 9 ( C = 0 ) , 1 6 0 1 , 1 4 9 6 , 1 4 4 6 , 1 1 7 1 , 7 6 3 , 700 c m " 1 . 1 H NMR ( 4 0 0 MHz) 5: 7 . 4 5 - 7 . 2 5 (m, 1 0 H , a r o m a t i c H ) , 3 . 1 3 ( d , I H , J = 10 H z , c y c l o p r o p y l C H ) , 2 . 7 0 ( d , I H , J = 10 H z , c y c l o p r o p y l C H ) , 2 . 6 6 -0 . 9 5 (m, 5 H , C O C H ( C H 2 C H 3 ) C H 2 ) , 0 . 7 4 ( t , 3 H , J = 7 H z , C H 2 C H 3 ) p p m . 1 3 C NMR ( 5 0 M H z ) 5 : 2 1 4 . 9 ( C = 0 ) , 1 4 3 . 2 3 , 1 3 5 . 1 2 , 1 2 9 . 3 7 , 1 2 8 . 8 5 , 1 2 7 . 3 3 , 1 2 7 . 1 6 , 1 2 7 . 0 5 ( a r o m a t i c C ) , 4 7 . 4 8 , 4 1 . 2 8 , 3 7 . 0 1 (3 x CH) , 4 1 . 4 0 , 3 4 . 3 6 , 2 3 . 4 7 ( C H 3 C H 2 , C H 2 a n d q u a t e r n a r y C ) , 1 1 . 2 9 ( C H 2 C H 3 ) p p m . - 240 -MS m / e ( r e l a t i v e i n t e n s i t y ) : 2 7 6 ( M + , 1 2 ) , 2 4 8 ( 3 0 ) , 219 ( 6 0 ) , 206 (100), 1 9 1 ( 6 5 ) , 165 ( 3 0 ) , 120 ( 6 4 ) , 115 ( 5 8 ) , 91 ( 9 6 ) . E x a c t m a s s c a l c u l a t e d f o r C2oH200: 276.1514. F o u n d : 276.1513. A n a l , c a l c d . f o r C 2 o H 2 0 0 : c . 86.92; H, 7 . 2 9 . F o u n d : C , 87.11; H, 7.28. 2 . D i b e n z o b a r r e l e n e D e r i v a t i v e s P h o t o c h e m i c a l S t u d i e s o n M e t h y l 3 , 5 - D i h y d r o - 3 - o x o - l H - 5 , 9 b [ 1 ' , 2 ' ] -b e n z e n o n a p h t h o [ 1 , 2 - c ] f u r a n - 4 - c a r b o x y l a t e ( 9 6 ) I n S o l u t i o n P h o t o l y s e s i n common o r g a n i c s o l v e n t s s u c h a s b e n z e n e , a c e t o n e ( t r i p l e t s e n s i t i z e r ) o r a c e t o n i t r i l e w e r e c a r r i e d o u t . I n a l l c a s e s , a s i n g l e p h o t o p r o d u c t w a s o b s e r v e d (GC c o n d i t i o n : D B - 1 c o l u m n , o v e n t e m p . = 2 2 0 ° C ) . O n a p r e p a r a t i v e s c a l e , a s o l u t i o n o f t h e t i t l e c o m p o u n d (50 mg) i n 20 mL o f b e n z e n e w a s d e g a s s e d a n d i r r a d i a t e d f o r 10 h r t o 100% c o n v e r s i o n . R e m o v a l o f t h e s o l v e n t g a v e 50 m g ( y i e l d 100%) o f m e t h y l 1 , 8 - d i h y d r o - 1 - o x o - l H - 3 a , 8 , 1 2 b - m e t h a n o d i b e n z o [ 3 , 4 : 6 , 7 ] c y c l o h e p t a [ 1 , 2 -c ] f u r a n - 1 2 c - c a r b o x y l a t e (153) a s a w h i t e s o l i d , w h i c h w a s r e c r y s t a l l i z e d f r o m d i e t h y l e t h e r a n d h e x a n e t o a f f o r d c o l o r l e s s p r i s m s , m . p . , 1 5 7 -1 5 9 ° C . I R ( K B r ) i / m a x : 1 7 6 8 ( l a c t o n e C = 0 ) , 1 7 2 5 ( C = 0 ) , 1 2 4 0 , 1 1 0 7 , 763, 741 c m " 1 . lH NMR ( 4 0 0 MHz) 6: 7 . 5 5 - 7 . 1 5 (m, 8 H , a r o m a t i c H), 5 . 1 7 ( s , I H , CH) , 4 . 9 3 , 5 . 1 5 ( t w o d , 2 H , J = 10 H z , C H 2 ) , 3 . 7 9 ( s , 3 H , 0 C H 3 ) p p m . 2 4 1 -L:>C NMR ( 7 5 MHz) 5 : 1 7 0 . 0 0 , 1 6 7 . 7 7 (2 x C=0) , 1 4 6 . 4 8 , 1 4 5 . 4 4 , 1 3 2 . 1 5 , 1 3 0 . 7 4 , 1 2 8 . 9 6 , 1 2 8 . 4 1 , 1 2 7 . 4 8 , 1 2 7 . 2 4 , 1 2 5 . 2 4 , 1 2 2 . 83 , 122 .56 , 121 .90 ( a r o m a t i c C ) , 6 9 . 4 7 , 6 2 . 8 2 , 5 7 . 7 1 ( c y c l o p r o p y l C ) , 6 4 . 4 1 ( C 0 2 C H 2 ) , 5 5 . 2 9 (CO2CH3), 5 2 . 6 0 ( C H ) p p m . MS m / e ( r e l a t i v e i n t e n s i t y ) : 318 ( M + , 4 3 . 1 ) , 2 9 0 ( 4 0 . 2 ) , 262 ( 3 6 . 5 ) , 2 3 0 ( 5 1 . 6 ) , 202 ( 1 0 0 ) , 101 ( 1 8 . 5 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 0 H 1 4 ° 4 : 3 1 8 . 0 8 9 2 . F o u n d : 3 1 8 . 0 8 9 2 . A n a l , c a l c d . f o r C20H14O4: C , 7 5 . 4 6 ; H , 4 . 4 3 . F o u n d : C , 7 5 . 1 9 ; H , 4.44. T h i s p h o t o p r o d u c t f r o m t h e s o l u t i o n p h a s e p h o t o l y s i s was a n a l y z e d b y ^H NMR w i t h t h e c h e m i c a l s h i f t r e a g e n t , E u ( h f c ) 3 , w h i c h s h o w e d a n e q u a l a m o u n t o f a p a i r o f e n a n t i o m e r s . I n t h e S o l i d S t a t e I r r a d i a t i o n o f t h e s a m p l e c r y s t a l s o r p o w d e r s w a s c a r r i e d o u t f o r d i f f e r e n t p e r i o d s o f t i m e s o t h a t t h e c o n v e r s i o n o f t h e s t a r t i n g m a t e r i a l v a r i e d f r o m 10% t o 100%. I t was f o u n d t h a t two p h o t o p r o d u c t s w e r e f o r m e d i n t h e s o l i d a n d t h a t o n e o f t h e m , t h e m a j o r p r o d u c t 1 5 3 , w a s t h e s a m e a s t h a t f r o m t h e p h o t o l y s i s i n s o l u t i o n . I t was a l s o d e t e r m i n e d t h a t t h e r a t i o b e t w e e n t h e t w o p h o t o p r o d u c t s i n t h e s o l i d s t a t e w a s c o n v e r s i o n i n d e p e n d e n t . T y p i c a l l y , 5 -10 mg o f t h e c o l o r l e s s c r y s t a l s w e r e p l a c e d i n a P y r e x t u b e w h i c h was p u r g e d w i t h n i t r o g e n , a n d p h o t o l y z e d f o r a b o u t 10-20 h r ( t h e p h o t o l y s i s c a n b e m o n i t o r e d b y G C ) . A f t e r t h e i r r a d i a t i o n , t h e y e l l o w c r y s t a l s w e r e d i s s o l v e d i n CDCI3. T h e p h o t o p r o d u c t s a n d p r o d u c t r a t i o w e r e a n a l y z e d b y b o t h ^H NMR a n d G C - M S . O n a p r e p a r a t i v e s c a l e , t h e c r y s t a l s ( 2 0 0 mg) w e r e s l i g h t l y p o w d e r e d a n d p l a c e d b e t w e e n m i c r o s c o p e s l i d e s . T h e n t h e s a m p l e was i r r a d i a t e d f o r 4 0 - 242 -h r u s i n g t h e H a n o v i a m e d i u m p r e s s u r e m e r c u r y l a m p . T h e r e s u l t i n g y e l l o w p o w d e r w a s s u b j e c t e d t o c o l u m n c h r o m a t o g r a p h y . H o w e v e r , a t t e m p t s t o s e p a r a t e t h e t w o p h o t o p r o d u c t s w e r e n o t s u c c e s s f u l r e g a r d l e s s o f h o w t h e e l u t i n g s o l v e n t o r t h e s t a t i o n a r y p h a s e ( s i l i c a g e l o r a l u m i n a ) w e r e v a r i e d . O n l y a s m a l l a m o u n t o f t h e m a j o r p h o t o p r o d u c t w a s i s o l a t e d . T h e m i n o r s o l i d s t a t e p h o t o p r o d u c t w a s e n r i c h e d u p t o 50% p u r e b y r e p e a t e d c o l u m n c h r o m a t o g r a p h y . T h i s m i x t u r e was a n a l y z e d b y ^H NMR a n d G C - M S a n d p r o v e d t o c o n s i s t o f t h e d i b e n z o p e n t a l e n e - l a c t o n e 1 5 2 , a r e g i o i s o m e r o f t h e m a j o r p h o t o p r o d u c t . T h e s t r u c t u r e o f t h i s was a l s o c o n f i r m e d b y a n i n d e p e n d e n t s y n t h e s i s . I n d e p e n d e n t P r e p a r a t i o n o f D i b e n z o p e n t a l e n e - l a c t o n e 152 p - T o l u e n e s u l f o n i c a c i d ( h y d r a t e d , 5 7 . 5 mg) d i s s o l v e d i n 4 0 mL o f b e n z e n e w a s r e f l u x e d f o r 1 h r , a n d w a t e r w a s ' r e m o v e d b y a D e a n - S t a r k t u b e . D i m e t h y l 4 b - h y d r o x y m e t h y l - 4 b , 8 b , 8 c , 8 d - t e t r a h y d r o d i b e n z o [ a , f ] -c y c l o p r o p a [ c , d ] p e n t a l e n e - 8 b , 8 c - d i c a r b o x y l a t e ( 1 1 9 ) ( 1 9 0 mg) d i s s o l v e d i n 4 mL o f b e n z e n e was p o u r e d i n t o t h e a b o v e c o o l e d s o l u t i o n , a n d t h e m i x t u r e w a s r e f l u x e d f o r 3 h r . T h e b e n z e n e l a y e r w a s w a s h e d w i t h 3% a q u e o u s s o d i u m b i c a r b o n a t e , w a t e r a n d d r i e d . R e m o v a l o f t h e s o l v e n t i n v a c u u m l e f t 1 9 0 mg o f a n o i l w h i c h c r y s t a l l i z e d u p o n s t a n d i n g . R e c r y s t a l l i z a t i o n f r o m a c e t o n e a f f o r d e d 1 3 0 mg ( y i e l d 75%) o f c o l o r l e s s p r i s m s , m . p . , 2 4 8 - 2 5 0 ° C . I R ( K B r ) i / m a x : 1 7 7 5 ( l a c t o n e 0 - 0 ) , 1 7 2 7 ( C = 0 ) , 1 4 7 4 , 1 3 6 6 , 1 3 4 3 , 1 2 0 8 , 1 1 7 4 , 1 0 8 0 , 1 0 3 7 , 9 1 5 , 749 c m " 1 . X H NMR ( 4 0 0 MHz) 5: 7 . 6 2 - 7 . 1 3 (m, 8 H , a r o m a t i c - H ) , 5 . 1 2 - 5 . 0 3 ( two d , 2 H , J - 11 H z , C H 2 ) , 4 . 8 5 ( s , I H , C H ) , 3 . 9 4 ( s , 3 H , COOCH3) p p m . - 243 liC NMR (75 MHz) 8: 172.00, 166.73 (2 x C=0) , 151.00, 150.66, 135.22, 132.94, 131.75, 128.83, 128.71, 128.09, 128.02, 127.81, 126.26, 120 .61, 120.56 (aromatic C ) , 75.52, 66.69, 57.34 (quaternary C ) , 72.41 ( C 0 2 C H 2 ) , 52.96 (CH), 50.96 (C0 2 CH 3 ) ppm. MS m/e ( r e l a t i v e i n t e n s i t y ) : 318 ( M + , 5 .9 ) , 274 ( 5 .1 ) , 260 (35.0), 242 (10.5), 231 (10.3), 215 (90.8), 202 (35.5), 107 (10 .5) , 84 (83.1), 69 (52.5), 49 (100.0). Exact mass c a l c u l a t e d f o r C20H14O4: 318.0892. Found: 318.0898. A n a l , c a l c d . fo r C 2 0 H 1 4 0 4 : C , 7 5 . 4 6 ; H, 4 . 4 3 . Found: C , 7 5 . 6 0 ; H, 4 . 4 2 . Asymmetric Syn thes i s i n the S o l i d S ta te T y p i c a l l y , a s i n g l e c r y s t a l (weighing ca . 5-20 mg i n each run ) o f the l a c t o n e - e s t e r 96, space group P2x2^2x, was i r r a d i a t e d w i t h the Hanovia medium pressure mercury lamp or the n i t r o g e n l a s e r fo r 20-40 hours a t v a r i o u s temperatures. The pho to lyzed c r y s t a l s were d i s s o l v e d i n CDCI3 and subjec ted to GC and ^H NMR a n a l y s i s . In the l a t t e r case , a c h i r a l s h i f t reagent , t r i s [ 3 - ( h e p t a f l u o r o p r o p y l h y d r o x y m e t h y l e n e ) - ( + ) -camphoratol] europium ( I I I ) (Eu(h fc )3 , A l d r i c h ) was a p p l i e d to determine the enant iomer ic excess which was determined by the i n t e g r a t i o n o f the s h i f t e d peaks. [2+2] C y c l o a d d i t i o n of the Lac tone -Es te r 96 to 1 ,3 -Cyclohexadiene A n a l y t i c a l pho to lyses o f the [2+2] c y c l o a d d i t i o n r e a c t i o n were c a r r i e d out i n benzene or a c e t o n i t r i l e . S e n s i t i z a t i o n experiments were performed u s i n g pure acetone or b e n z i l i n benzene as s e n s i t i z e r s ; a - 244 -uranium g la s s f i l t e r was a p p l i e d i n the l a t t e r case . I n a l l runs , the r e a c t i o n was monitored by GC (DB-1 or DB-17 column). On a p repa ra t i ve s c a l e , the l a c t o n e - e s t e r 96 (300 mg, 0.94 mmoles) and f r e s h l y d i s t i l l e d 1 ,3-cyclohexadiene (1 .0 g , 12 mmoles) i n 10 mL o f acetone were pho to lyzed f o r 5 hour s . Removal o f the s o l v e n t gave an o i l which was chromatographed on s i l i c a g e l by u s i n g 15 % d i e t h y l e ther i n hexanes as the e l u t i n g s o l v e n t ; 97 mg ( y i e l d 26%) of whi te c r y s t a l s were i s o l a t e d by c r y s t a l l i z a t i o n o f the appropr ia te column f r a c t i o n s as the major [2+2] adduct 187. Three a d d i t i o n a l photoproducts , 188, 189 and 190 were a l s o i s o l a t e d i n a s m a l l amounts. (a) C h a r a c t e r i z a t i o n of the Major [2+2] Adduct 187. m.p. 237-238°C. IR (KBr) i / m a x : 1780 ( l ac tone C=0), 1723 (C=0), 1458, 1432, 1279, 1235, 1045, 1010, 777, 639 c m " 1 . 1 H NMR (400 MHz) 6": 7 .55-7 .10 (m, 8H, aromatic H) , 5 .95-5.73 (m, 2H, CH=CH) , 5 .31 , 4.88 (two d, 2H, J = 10 Hz, CH 20C0) , 4.67 ( s , IH, br idgehead CH), 3.44 (s , 3H, C 0 2 C H 3 ) , 3 .40-1.35 (m, 6H, -CH 2 CH 2 CH(R)CH-) ppm. 1 3 C NMR (50 MHz) 5: 170.87, 170.05 (2 x C=0) , 141.84, 140.57, 140.32, 137.52, 129.64, 127.11, 126.93, 126.79, 126.759*, 124.70, 124.47, 122.49, 121.33 (aromat ic C and v i n y l i c C ) , 63 .53 , 21 .48, 20.57 (3 x C H 2 ) , 58 .81 , 58.23, 55.96 (3 x quaternary C ) , 54.26, 51.22, 33.92, 32.81 (CO2CH3, 3 x CH) ppm. * p o s s i b l y two carbons he re . 7 2 4 5 -MS m / e ( r e l a t i v e i n t e n s i t y ) : 3 9 8 ( M + , 2), 3 6 6 (8), 338 (5), 319 (100), 2 8 7 ( 1 9 ) , 2 5 9 (43), 215 (37), 202 ( 3 0 ) , 1 9 1 ( 6 3 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 6 H 2 2 ° 4 : 3 9 8 . 1 5 1 9 . F o u n d : 3 9 8 . 1 5 2 3 . A n a l , c a l c d . f o r C26H22O4: C , 78.37; H , 5.57. F o u n d : C , 78.54; H , 5.54. T h e r e g i o - a n d s t e r e o c h e m i s t r y o f p h o t o p r o d u c t 187 w e r e d e t e r m i n e d b y p r o t o n d e c o u p l i n g , NOE d i f f e r e n c e a n d 2D C O S Y NMR e x p e r i m e n t s . S e e t e x t f o r d e t a i l s . ( b ) C h a r a c t e r i z a t i o n o f t h e M i n o r [2+2] A d d u c t 188 ( c a . 65% p u r e ) . T h i s p r o d u c t w a s o b t a i n e d a s a n o i l . L H NMR ( 4 0 0 MHz) 6: 7.60-7.00 ( m , 8H, a r o m a t i c H) , 5.97, 5 . 2 8 (m, 2 H , C H = C H ) , 5 . 4 0 , 4.88 ( t w o d , 2 H , J = I I H z , CH2OCO) , 4.57 ( s , I H , b r i d g e h e a d CH) , 3 . 3 2 ( s , 3H, C 0 2 C H 3 ) , 2 . 3 0-1 . 5 0 (m , 6 H , C H 2 C H 2 C H R C H R ) p p m . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 398 ( M + , 9), 366 ( 2 2 ) , 319 ( 1 0 0 ) , 287 ( 3 5 ) , 260 ( 6 7 ) , 247 (79), 215 ( 4 0 ) , 1 9 1 ( 6 9 ) , 80 ( 6 2 ) . E x a c t m a s s c a l c u l a t e d f o r 0 2 6 ^ 0 4 : 3 9 8 . 1 5 1 9 . F o u n d : 3 9 8 . 1 5 2 7 . T h e r e g i o - a n d s t e r e o c h e m i s t r y w e r e d e t e r m i n e d b a s e d o n p r o t o n d e c o u p l i n g a n d NOE d i f f e r e n c e e x p e r i m e n t s . S e e t e x t f o r d e t a i l s . ( c ) C h a r a c t e r i z a t i o n o f M e t h y l 3 , 3 a , 5 - T r i h y d r o - 3 - o x o - c i s - 4 -c y c l o h e x a d i e n y l - l H - 5 , 9 b [ 1 ' , 2 ' ] b e n z e n o n a p h t h o [ 1 , 2 - c ] f u r a n - 4 - c a r b o x y l a t e (189). 2 m g , m . p . 1 4 5 - 1 5 0 C C . I R ( K B r ) i / m a x : 1777 ( l a c t o n e C=0) , 1 7 2 3 (C=0) , 1 4 5 8 , 1 3 0 1 , 1 2 2 0 , 1 1 3 8 , 1 0 2 1 , 7 6 0 , 683 c m " 1 . - 246 L H NMR ( 4 0 0 MHz) 6: 7 . 6 0 - 7 . 0 0 (m, 8 H , a r o m a t i c H) , 6 . 1 9 - 5 . 6 8 (m, 4 H , 2 x C H = C H ) , 5 . 3 8 , 5 . 0 3 ( t w o d , 2 H , J = 11 H z , C H 2 O C O ) , 5 . 0 0 ( s , I H , b r i d g e h e a d C H ) , 3 . 8 9 ( s , I H , C H C 0 2 ) , 3 . 5 5 ( s , 3 H , C 0 2 C H 3 ) , 2 . 9 0 - 2 . 8 0 (m, I H , C H R ( C H = C H ) 2 ) , 2 . 5 9 (m , 2 H , C H 2 ( C H = C H ) 2 ) p p m . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 3 9 8 ( M + , 6 ) , 1 9 1 ( 6 0 ) , 1 4 8 ( 1 5 ) , 1 0 4 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 g H 2 2 0 4 : 3 9 8 . 1 5 1 9 . F o u n d : 3 9 8 . 1 5 1 3 . T h e r e g i o - a n d s t e r e o c h e m i s t r y w e r e d e t e r m i n e d b a s e d o n p r o t o n d e c o u p l i n g a n d NOE d i f f e r e n c e e x p e r i m e n t s . S e e t e x t f o r d e t a i l s . ( d ) C h a r a c t e r i z a t i o n o f M e t h y l c i s - 3 , 3 a , 4 , 5 - T e t r a h y d r o - 3 - o x o - l H -5 , 9 b [ l ' , 2 ' ] b e n z e n o n a p h t h o t l , 2 - c ] f u r a n - 4 - c a r b o x y l a t e ( 1 9 0 ) ( c a . 60% p u r e ) . 1 H NMR ( 4 0 0 MHz) 5 : 7 . 5 5 - 7 . 0 0 (m, 8 H , a r o m a t i c H) , 5 . 4 8 , 5 . 1 1 ( t w o d , 2 H , J = 10 H z , C H 2 0 C 0 ) , 4 . 7 7 ( d , I H , J = 1 H z , b r i d g e h e a d C H ) , 3 . 7 2 ( s , 3 H , C 0 2 C H 3 ) , 3 . 2 9 ( d , I H , J = 7 H z , C H ) , 3 . 0 4 ( d d , I H , J = 7 Hz a n d 1 H z , CH) p p m . G C - M S m / e ( r e l a t i v e i n t e n s i t y ) : 3 2 0 ( M + , 5 5 ) , 1 9 1 ( 1 0 0 ) . E x a c t m a s s c a l c u l a t e d f o r C ^ H ^ O ^ 3 2 0 . 1 0 4 9 . F o u n d : 3 2 0 . 1 0 4 9 . [2+2] C y c l o a d d i t i o n o f t h e L a c t o n e - E s t e r 96 w i t h 2 , 5 - D i m e t h y l - 2 , 4 -h e x a d i e n e A n a l y t i c a l p h o t o l y s e s w e r e p e r f o r m e d i n b e n z e n e o r a c e t o n i t r i l e . S e n s i t i z a t i o n e x p e r i m e n t w a s c a r r i e d o u t u s i n g p u r e a c e t o n e a s s e n s i t i z e r . I n a l l c a s e s , t h e [2+2] r e a c t i o n s w a s a n a l y z e d b y GC ( D B - 1 o r D B - 1 7 c o l u m n ) . - 247 O n a p r e p a r a t i v e s c a l e , a s o l u t i o n o f t h e l a c t o n e - e s t e r 96 ( 9 0 m g , 0 . 2 8 m m o l e s ) a n d 2 , 5 - d i m e t h y l - 2 , 4 - h e x a d i e n e ( 1 0 0 m g , 1 . 1 m m o l e s ) i n 5 mL o f b e n z e n e w a s i r r a d i a t e d f o r 1 h o u r . R e m o v a l o f t h e s o l v e n t l e f t a n o i l w h i c h w a s c h r o m a t o g r a p h e d o n s i l i c a g e l b y u s i n g 20% e t h y l a c e t a t e a n d p e t r o l e u m e t h e r ( 3 0 - 6 0 ° ) a s t h e e l u t i n g s o l v e n t . T h e s e p a r a t i o n w a s a s f o l l o w s : 4 9 mg (95% p u r e b y G C , 40% y i e l d ) o f a n o i l y s a m p l e w h i c h was c h a r a c t e r i z e d a s t h e [2+2] c y c l o a d d i t i o n a d d u c t 1 8 5 , 25 mg o f a 1 :1 m i x t u r e o f 185 a n d t h e s t e r e o i s o m e r 186 a n d 33 mg o f t h e r e a r r a n g e d p h o t o p r o d u c t 1 5 3 . ( a ) C h a r a c t e r i z a t i o n o f t h e [2+2] P h o t o p r o d u c t 1 8 5 . T h i s p r o d u c t w a s o b t a i n e d a s a n o i l . X H NMR ( 4 0 0 M H z ) 6: 7 . 6 5 - 7 . 0 0 (m, 8 H , a r o m a t i c H ) , 5 . 2 8 , 4 . 6 9 ( t w o d , 2 H , J = 10 H z , C H 2 0 C 0 ) , 5 . 1 4 (m , . I H , C H = C ( C H 3 ) 2 ) . , 4 . 7 0 ( s , I H , b r i d g e h e a d CH) , 3 . 3 0 ( b r o a d s , 3 H , C 0 2 C H 3 ) , 2 . 1 3 ( d , I H , J = 11 H z , ( C H 3 ) 2 C = C H - C H ) , 1 . 6 6 , 1 . 2 2 ( t w o d , 6 H , J = 1 H z , ( C H 3 ) 2 C = C H ) , 1 . 1 9 , 1 . 0 8 ( t w o s , 6 H , 2 x C H 3 ) p p m . G C - M S m / e d e t e r m i n e d b y c h e m i c a l i o n i z a t i o n ( r e l a t i v e i n t e n s i t y ) : 4 2 9 ( M + l , 1 0 0 ) , 1 1 0 ( 6 5 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 8 H 2 g 0 4 : 4 2 8 . 1 9 8 8 . F o u n d : 4 2 8 . 1 9 9 3 . T h e r e g i o - a n d s t e r e o c h e m i s t r y o f p h o t o p r o d u c t 185 w e r e d e t e r m i n e d b y NMR p r o t o n d e c o u p l i n g a n d N O E d i f f e r e n c e e x p e r i m e n t s . S e e t e x t f o r d e t a i l s . ( b ) C h a r a c t e r i z a t i o n o f P h o t o p r o d u c t 186 ( f r o m a m i x t u r e o f t h e i s o m e r s 1 8 5 a n d 1 8 6 ) . l t i NMR ( 4 0 0 MHz) 6: 7 . 7 0 - 7 . 0 5 (m, 8 H , a r o m a t i c H ) , 5 . 3 1 , 4 . 7 7 ( t w o d , 2 H , J = 10 H z , C H 2 0 C 0 ) , 4 . 7 4 ( s , I H , b r i d g e h e a d C H ) , 3 . 3 8 ( d , I H , J = - 248 -9 H z , ( C H 3 ) 2 C = C H - C H ) , 3 . 3 3 ( b r o a d s , 3 H , C 0 2 C H 3 ) , 3 . 0 5 ( d , I H , J = 9 H z , ( C H 3 ) 2 C - = C H - C H ) , 1 . 6 0 , 1 . 5 1 , 1 . 3 1 , 1 . 1 3 ( f o u r s , 1 2 H , 4 x C H 3 ) p p m . G C - M S m / e d e t e r m i n e d b y c h e m i c a l i o n i z a t i o n ( r e l a t i v e i n t e n s i t y ) : 4 2 9 ( M + l , 1 0 0 ) , 1 1 0 ( 9 6 ) . E x a c t m a s s c a l c u l a t e d f o r C 2 s H 2 8 0 4 : 4 2 8 . 1 9 8 8 . F o u n d : 4 2 8 . 1 9 9 3 . T h e r e g i o - a n d s t e r e o c h e m i s t r y o f p h o t o p r o d u c t 1 8 6 w e r e d e t e r m i n e d b a s e d o n NMR p r o t o n d e c o u p l i n g a n d NOE d i f f e r e n c e e x p e r i m e n t s . S e e t e x t f o r d e t a i l s . P h o t o l y s i s o f D i m e t h y l 9 , 1 0 - D i h y d r o - 9 - f o r m y l - 9 , 1 0 - e t h e n o a n t h r a c e n e -1 1 , 1 2 - d i c a r b o x y l a t e ( 9 4 ) I n S o l u t i o n A n a l y t i c a l s o l u t i o n p h o t o l y s e s w e r e c a r r i e d o u t i n a c e t o n e , a c e t o n i t r i l e a n d b e n z e n e ; t h e p h o t o l y s a t e s w e r e a n a l y z e d b y GC ( D B - 1 c o l u m n , o v e n t e m p . = 2 1 0 ° C ) . I n a d d i t i o n , i r r