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X-ray crystallographic studies of four photoreactive tetrahydronaphthoquinol derivatives and five related.. 1982

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X-RAY CRYSTALLOGRAPHIC STUDIES OF FOUR PHOTOREACTIVE TETRAHYDRONAPHTHOQUINOL DERIVATIVES AND FIVE RELATED COMPOUNDS by ANTHONY SILVIO SECCO B . S c , S t . F r a n c i s X a v i e r U n i v e r s i t y , 1978 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF CHEMISTRY We accept t h i s t h e s i s as conforming to the r e q u i r e d standard . The U n i v e r s i t y of B r i t i s h Columbia March 1982 © Anthony S i l v i o Secco 1982 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of dA^vn' s The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6 (3/81) i i ABSTRACT The s t r u c t u r e s of four 4ap,5,8,8a$-tetrahydro-1 - naphthoquin-4-ol d e r i v a t i v e s have been s t u d i e d and r e l a t e d to t h e i r observed photochemical r e a c t i v i t y . H - a b s t r a c t i o n s are dominant i n the s o l i d s t a t e p h o t o l y s e s of these compounds because of t h e i r conformations and the topochemical c o n t r o l by the l a t t i c e . A l l s t r u c t u r e s have been s o l v e d by d i r e c t methods and r e f i n e d by l e a s t squares procedures. The 2,3,6,7- t e t r a m e t h y l - 4 o - o l d e r i v a t i v e , C,t,H 2o0 2, i s m o n o c l i n i c , space group C2/c, a = 13.898(3), b = 5.228(1), c = 17.316(3) A, fi = 97.442(7)° and Z = 4. T h i s s t r u c t u r e was r e f i n e d to R = 0.058 f o r 888 r e f l e c t i o n s . The 2,3- and 6,7-dimethyl-4o-ol compounds-C, 2H, 60 2 , are orthorhombic, space group £2,2,2,, and m o n o c l i n i c , space group £2i/c, r e s p e c t i v e l y . For the 2,3- d e r i v a t i v e , a = 5.148(1), b = 12.269(2), c = 16.478(3) A, Z = 4 and the refinement of 671 data l e d to an R of 0.031. The 6,7- compound, a = 9.242(3), b = 22.724(3), c = 5.139(2) A, fi = 102.7(1)°, Z = 4, was r e f i n e d to R = 0.032 f o r 626 data. 2,3,4o,4a£,6,7,8ap-heptamethyl-4p-ol, C 1 7 H 2 6 0 2 , i s m o n o c l i n i c , space group £2,/c, a = 7.497(2), b = 16.792(3), c = 12.687(3) A, p = 105.30(1)° and Z = 4. An R-value of 0.041 was obtained from the refinement of 1934 r e f l e c t i o n s . The above compounds have s i m i l a r conformations which are f a v o r a b l e to H - a b s t r a c t i o n r e a c t i o n s . The 6,7-dimethyl-1o,4o-diol C , 2 H 1 8 0 2 , c r y s t a l l i z e s i n the mon o c l i n i c system, space group £2i/c, a = 13.870(2), b = 18.025(4), c = 9.236(1) A, *> = 108.098(6)° , Z = 8 and was r e f i n e d to R = 0.032 f o r 1461 r e f l e c t i o n s . The d i o l compound adopts the same conformation as those above but i s not p h o t o r e a c t i v e . The f o l l o w i n g four compounds were d e r i v e d from e i t h e r t e t r a h y d r o n a p h t h o q u i n o l p r o g e n i t o r s or t h e i r o x i d i z e d forms, tetrahydronaphthoquinones. A t w i s t a n e - 1 i k e s t r u c t u r e , twistenone C 1 0 H 1 0 0 2 , was found to c r y s t a l l i z e i n the monoclinic system, space group P2,/n, a = 6.381(2), b = 19.454(2), c = 6.708(2) A, <3 = 1 06.24( 1 )° and Z = 4. Refinement of 930 r e f l e c t i o n s converged at R = 0.037. 5-(2,3-dimethylphenyl)-y- b u t y r o l a c t o n e c r y s t a l s , C 1 2H,,0 2 r are m o n o c l i n i c , space group P2,/n, a = 10.847(3), b = 6.924(1), c = 13.654(4) A, I = 95.22(1)° and Z = 4. The s t r u c t u r e was r e f i n e d to R = 0.057 f o r 569 r e f l e c t i o n s . I t was hoped that e l u c i d a t i o n of t h i s s t r u c t u r e would a i d i n determining the intermediate compound from which i t was formed. The methylene ketone C 1 7 H 2 « 0 , d e r i v e d from the a c e t y l a t i o n product of the p r e v i o u s l y d e s c r i b e d heptamethyl-40-ol, i s m o n o c l i n i c , space group P2,/a, a = 12.374(2), b = 8.771(1), c = 13.743(2) A, fi = 104.027(6)° , Z = 4 and r e f i n e d to R = 0.037 f o r 1369 data. A r e a c t i o n designed to p i n a c o l i z e a diketone cage compound r e s u l t e d i n a d i f f e r e n t product from which the hydroxy mesylate d e r i v a t i v e C 1 7 H 2 8 0 „ S , was formed. The c r y s t a l s are m o n o c l i n i c , space group P2,/c, a = 9.246(2), b = 10.938(1), c = 17.335(4) A, 0 = 102.11(1)° and Z = 4. Refinement converged at R = 0.042 f o r 2995 r e f l e c t i o n s . i v TABLE OF CONTENTS T i t l e Page i A b s t r a c t i i Table Of Contents i v L i s t Of Tables v i i L i s t Of F i g u r e s x Acknowledgement x i i GENERAL INTRODUCTION 1 C r y s t a l l o g r a p h i c I n t r o d u c t i o n 2 Data C o l l e c t i o n 2 Determination Of C e l l Constants 5 Data Reduction 5 S o l u t i o n By D i r e c t Methods ; 6 Refinement 11 Chemical I n t r o d u c t i o n 12 Photochemistry: 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 .. 12 T h e s i s O u t l i n e 19 Schematic Of The T h e s i s Layout 21 PART I 22 CHAPTER I: 2,3,6,7-TETRAMETHYL-4a£,5,8,8ap~TETRAHYDRO- 1 -NAPHTHOQUIN- 4o-OL .- 23 I n t r o d u c t i o n 24 Experimental 24 S o l u t i o n And Refinement 27 D i s c u s s i o n 30 CHAPTER I I : 2,3-DIMETHYL-4a*,5,8,8a0-TETRAHYDRO-1- V NAPHTHOQUIN-4a-OL AND 6,7-DIMETHYL-4afi,5,8,8ap-TETRAHYDRO-1-NAPHTHOQUIN-4o -OL 42 I n t r o d u c t i o n 43 Experimental 43 S o l u t i o n And Refinement 46 2 , 3-Dimethyl-4a0,5,8,8ap-tetrahydro-1-naphthoquin-4a~ o l 46 6,7-Dimethyl-4a0,5,8,8a$-tetrahydro-1-naphthoquin-4o- o l 47 D i s c u s s i o n 48 CHAPTER I I I : 2,3,4c,4a0,6,7,8a*-HEPTAMETHYL-4a0,5,8,8a0- TETRAHYDRO-1-NAPHTHOQUIN-4 0-OL 65 I n t r o d u c t i o n 66 Experimental 66 S o l u t i o n And Refinement 68 D i s c u s s i o n 69 Comparison Of Compounds ( I I I ) - ( V I I ) 75 CHAPTER IV: 6,7-DIMETHYL-4a0,5,8,8a0-TETRAHYDRONAPHTHOQUIN- 1c,4o-DIOL 94 I n t r o d u c t i o n 95 Experimental 96 S o l u t i o n And Refinement 98 D i s c u s s i o n 103 Comparison With Tetrahydronaphthoquin-4c-ols 112 Asymmetric U n i t S i z e - S t r u c t u r e Comparison 118 PART II 120 CHAPTER V: A TWISTANE DERIVATIVE (TWISTENONE) 121 v i I n t r o d u c t i o n 122 Experimental 124 S o l u t i o n And Refinement 125 D i s c u s s i o n 126 CHAPTER VI: 5-(2,3-DIMETHYLPHENYL)-r-BUTYROLACTONE 137 I n t r o d u c t i o n 138 Experimental 139 S o l u t i o n And Refinement 140 D i s c u s s i o n k 143 CHAPTER V I I : 1,3,4,5,6,9-HEXAMETHYL-8-EXO-METHYLENETRICYCLO [4.4.0.0 3- 9 ]DEC-4-ENE-2-ONE 154 I n t r o d u c t i o n 155 Experimental 155 S o l u t i o n And Refinement .. 157 D i s c u s s i o n 161 CHAPTER V I I I : 1,2,3,5,6,8-HEXAMETHYL-4-MESYL-7-HYDROXY- TETRACYCLO[ 4.2.1 .1 2-5 - 0 3-7 ]DECANE 172 I n t r o d u c t i o n 173 Experimental 173 S o l u t i o n And Refinement 176 D i s c u s s i o n 181 SUMMARY 1 90 References 193 SUPPLEMENTARY MATERIAL 198 v i i LIST OF TABLES GENERAL INTRODUCTION 1 PART I 22 CHAPTER I 23 I. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 31 I I . A n i s o t r o p i c thermal parameters •• 32 I I I . Bond lengths and angles 36 IV. Bond lengths and angles i n v o l v i n g hydrogen atoms " 37 V. T o r s i o n angles 39 CHAPTER II 42 VI. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 48 V I I . A n i s o t r o p i c thermal parameters 50 V I I I . T o r s i o n angles 51 IX. Geometrical parameters i n the p-enone a b s t r a c t i o n r e a c t i o n 57 X. Bond lengths and angles 61 CHAPTER I I I 65 XI. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 70 XI I . A n i s o t r o p i c thermal parameters 72 X I I I . Parameters r e l e v a n t to photochemical a c t i v i t y i n the d e r i v a t i v e s ; 77 XIV. Bond lengths i n the d e r i v a t i v e s 82 XV. Bond angles i n the d e r i v a t i v e s 83 XVI. T o r s i o n angles i n the d e r i v a t i v e s 86 XVII. Supplementary bond l e n g t h s and angles i n (VI) . 88 v i i i XVIII. Bond lengths i n v o l v i n g hydrogen atoms i n (VI) . 89 XIX. Bond angles i n v o l v i n g hydrogen atoms i n (VI) .. 90 XX. Supplementary t o r s i o n angles i n (VI) 91 CHAPTER IV 94 XXI. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 100 XXII. A n i s o t r o p i c thermal parameters 102 XXIII. Bond lengths 106 XXIV. Bond angles 107 XXV. Bond lengths i n v o l v i n g hydrogen atoms 108 XXVI. Bond angles i n v o l v i n g hydrogen atoms 109 XXVII. Hydrogen bonding geometries 111 XXVIII. T o r s i o n angles 113 PART II 120 CHAPTER V 121 XXIX. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 127 XXX. A n i s o t r o p i c thermal parameters 128 XXXI. Bond lengths 129 XXXII. Least squares planes 130 , XXXIII. Bond angles 135 CHAPTER VI 137 XXXIV. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 144 XXXV. A n i s o t r o p i c thermal parameters 145 XXXVI. Bond lengths and angles 148 XXXVII. Bond lengths and angles i n v o l v i n g hydrogen atoms 149 XXXVIII. T o r s i o n angles 150 CHAPTER VII 154 XXXIX. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 159 ix XL. A n i s o t r o p i c thermal parameters 160 XLI. Bond angles 162 XLII. Bond angles i n v o l v i n g hydrogen atoms 164 X L I I I . T o r s i o n angles 165 XLIV. Bond lengths 168 XLV. Bond lengths i n v o l v i n g hydrogen atoms 169 CHAPTER VIII 172 XLVI. P o s i t i o n a l and i s o t r o p i c thermal parameters ... 178 XLVII. A n i s o t r o p i c thermal parameters 180 XLVIII. T o r s i o n angles 183 XLIX. Bond lengths 185 L. Bond angles 186 X LIST OF FIGURES GENERAL INTRODUCTION 1 1. D e f i n i t i o n s of T q and A Q 15 2. Pr o d u c t i o n of 4ap,5,8,8ap-tetrahydro-1 - napHthoquin-4-ols 16 3. Conformations i n naphthoquinols 18 4. D e f i n i t i o n s of T c and 18 5. R e l a t i o n s h i p of the d i o l to naphthoquinones and naphthoquinols 20 PART I 22 CHAPTER I 23 6. P r e p a r a t i v e r e a c t i o n scheme 25 7. E-map; p r o j e c t i o n onto l e a s t squares plane through e l e c t r o n d e n s i t y peaks 29 8. Stereo diagram of the molecular packing of type A molecules 34 9. Stereo diagram of the molecule 35 CHAPTER II 42 10. Stereo diagrams of the molecules 56 11. Stereo packing diagrams ... 59 CHAPTER III 65 12. Stereo diagram of the molecule 73 13. Stereo packing diagram 75 CHAPTER IV 94 14. Stereo diagram of a type A molecule 103 15. Stereo packing diagram 104 x i PART II 120 CHAPTER V 121 16. R e s u l t s of d i f f e r e n t methods of i r r a d i a t i o n 123 17. T o r s i o n angles 131 18. T o r s i o n angles i n twistane and the i d e a l i z e d t w i s t - b o a t conformation 133 19. Stereo diagram of the molecule 134 20. Stereo packing diagram 136 CHAPTER VI 137 21. Reaction scheme l e a d i n g to the lac t o n e 139 22. Stereo diagram of the molecule 146 23. Stereo packing diagram 147 CHAPTER VII 154 24. Reaction scheme l e a d i n g to the methylene ketone .. 156 25. Stereo diagrams of the molecule and the contents of the u n i t c e l l 171 CHAPTER VIII 172 26. Reaction scheme l e a d i n g to the hydroxy mesylate d e r i v a t i v e 174 27. Stereo packing diagram 181 28. Stereo diagram of the molecule 188 i x i i ACKNOWLEDGEMENT I wish to express my s i n c e r e thanks and a p p r e c i a t i o n to P r o f e s s o r James T r o t t e r f o r a l l o w i n g me to become a pa r t of h i s re s e a r c h group and f o r the guidance and advice he has given me du r i n g the course of my graduate s t u d i e s . I am g r a t e f u l t o Dr. J . R. S c h e f f e r and members of h i s res e a r c h group ( e s p e c i a l l y Leueen Walsh) f o r p r o v i d i n g c r y s t a l s , photochemistry r e s u l t s and background i n f o r m a t i o n . I am a l s o indebted to Drs. S. J . R e t t i g , R. G. B a l l and R. A. P a u p t i t f o r t h e i r u n y i e l d i n g p a t i e n c e , g e n e r o s i t y with t h e i r time and the he l p they have given me du r i n g my l e a r n i n g of c r y s t a l l o g r a p h i c procedures and techniques. I g r a t e f u l l y acknowledge the N a t u r a l Sciences and En g i n e e r i n g Research C o u n c i l of Canada f o r f i n a n c i a l support throughout my graduate s t u d i e s . 1 GENERAL INTRODUCTION 2 C r y s t a l l o g r a p h i c I n t r o d u c t i o n The fundamental p r i n c i p l e s and techniques of X-ray d i f f r a c t i o n i n c r y s t a l s t r u c t u r e a n a l y s i s are given i n s e v e r a l t e x t s (1-6). In a d d i t i o n , the v a r i o u s methods of o b t a i n i n g a s t r u c t u r a l s o l u t i o n and r e f i n i n g that s o l u t i o n given a r e l i a b l e data set have been well-developed and e l e g a n t l y communicated by a number of authors (7-15). Throughout the t e x t that f o l l o w s , r e f e r e n c e s w i l l be made to these i n v a l u a b l e c o n t r i b u t o r s i n c o n j u n c t i o n with t h e i r c o n t r i b u t i o n s to the a r t of c r y s t a l l o g r a p h y . The g e n e r a l procedures of data c o l l e c t i o n and s t r u c t u r a l s o l u t i o n and refinement are common to a l l s t r u c t u r e s presented i n t h i s work. I t i s hoped that an o u t l i n e of these procedures w i l l enable the reader to a p p r e c i a t e b e t t e r the ensuing experimental s e c t i o n s . Data c o l l e c t i o n Data f o r a l l s t r u c t u r e s were measured on an Enraf-Nonius CAD4 automatic d i f f T a c t o m e t e r . U s u a l l y , a c r y s t a l i s mounted on the goniometer i n a general o r i e n t a t i o n . An automatic search r o u t i n e i s then invoked to expl o r e r e c i p r o c a l space i n a methodical manner i n an e f f o r t to f i n d up to a maximum of 25 r e f l e c t i o n s . Accurate p o s i t i o n i n g of these r e f l e c t i o n s i s e f f e c t e d by a c e n t e r i n g procedure i n which d i f f e r e n t types of scans and a p e r t u r e s are employed i n l o c a t i n g the r e f l e c t i o n peak-centers. The r e s u l t i n g s e t t i n g angles are used i n composing 3 a c o l l e c t i o n of v e c t o r s which i n c l u d e s the s c a t t e r i n g v e c t o r f o r each r e f l e c t i o n and the sum and d i f f e r e n c e v e c t o r s f o r each combination of two s c a t t e r i n g v e c t o r s . From t h i s v e c t o r set a p r i m i t i v e c e l l and o r i e n t a t i o n matrix are determined, and the r e f l e c t i o n s ' i n d i c e s are c a l c u l a t e d . Refinement of the o r i e n t a t i o n matrix, e f f e c t e d by f u r t h e r c e n t e r i n g of the r e f l e c t i o n s and fol l o w e d by a l e a s t squares f i t t i n g procedure, i s continued u n t i l the angular d e v i a t i o n between the r e a l s c a t t e r i n g v e c t o r (based on i n t e g r a l h , k , l values) and the s c a t t e r i n g v e c t o r c a l c u l a t e d from the most recent o r i e n t a t i o n matrix i s l e s s than 0.05° f o r a l l measured r e f l e c t i o n s . Once a s u i t a b l e o r i e n t a t i o n matrix i s obtained, the parameters to be employed i n data c o l l e c t i o n are chosen. A b r i e f d e s c r i p t i o n of the c o l l e c t i o n procedure with the most commonly a d j u s t e d parameters u n d e r l i n e d i s i n c l u d e d i n the f o l l o w i n g paragraphs. The r e g i o n of r e c i p r o c a l space to be exp l o r e d i s r e s t r i c t e d to a range of the t a v a l u e s which, f o r p r a c t i c a l purposes, i s l i m i t e d by the c r y s t a l ' s g e n e r a l s c a t t e r i n g a b i l i t y . An omega scan angle i s d e r i v e d from the ex p r e s s i o n (DOMA + DOMB*tan©) f o r each r e f l e c t i o n w i t h i n the theta l i m i t s . Whereas DOMB i s a constant (0.347 f o r Mo r a d i a t i o n ) r e q u i r e d i n c a l c u l a t i n g the widening of the r e f l e c t i o n due to the Ko,-Ro 2 s p l i t at high e- angles, DOMA v a r i e s from sample to sample and depends mainly on the mosaic spread i n the c r y s t a l . The a c t u a l scan i s extended 25% on each s i d e to i n c l u d e background measurement. The h o r i z o n t a l a p e r t u r e width at the d e t e c t o r i s a l s o c o n t r o l l e d as a f u n c t i o n of th e t a through the r e l a t i o n s h i p (APTA + t a n e ) , APTA being an a d j u s t a b l e parameter u s u a l l y assuming a value of 1.5- 4 2.5 mm. The v e r t i c a l a p erture i s s e l e c t e d p r i o r to data c o l l e c t i o n and c o n s i s t s of a manually i n s e r t a b l e s l i t (4 mm has been found to be a p p r o p r i a t e f o r most c r y s t a l s ) . The type of scan to be employed throughout the data c o l l e c t i o n i s determined from an a n a l y s i s of the peak p r o f i l e s of s e v e r a l r e f l e c t i o n s . Scan types range from pure o-scans to u-2(n/6)e scans, where n i s some i n t e g e r between 1 and 6. R e f l e c t i o n s are g e n e r a l l y c o l l e c t e d i n a z i g z a g mode i n which the i n d i c e s are stepped through, one by one, from t h e i r minimum to maximum values thereby exhausting the data p o i n t s i n that region of r e c i p r o c a l space. I n i t i a l l y each r e f l e c t i o n i s scanned at the maximum speed, and from the peak i n t e n s i t y and accompanying background counts a{M)/M i s c a l c u l a t e d (M = scan count - B; <y(M) = (scan count + 2B) V2 where M i s the measured i n t e n s i t y and B i s the time-averaged background). If t h i s value i s g r e a t e r than the prescan acceptance r a t i o R, the r e f l e c t i o n i s c l a s s i f i e d as weak, otherwise the «r(M)/M i s compared to the r a t i o R' requi red from the f i n a l scan data; a{M)/M "> R' f o r c e s a f i n a l scan to be c a r r i e d out at a speed p r o p o r t i o n a l to the square of the r a t i o [<r(M)/M]/R'; a l e s s - t h a n c o n d i t i o n i n d i c a t e s that the p r e l i m i n a r y scan data are good and no a d d i t i o n a l scan i s r e q u i r e d . O r i e n t a t i o n c o n t r o l r e f l e c t i o n s are checked p e r i o d i c a l l y d u r i n g data c o l l e c t i o n to ensure proper c r y s t a l o r i e n t a t i o n . Each r e f l e c t i o n i s scanned to determine the peak c e n t e r . The b i s e c t i n g v e c t o r f o r the r e f l e c t i o n i s compared with the s c a t t e r i n g v e c t o r c a l c u l a t e d from the c u r r e n t o r i e n t a t i o n m atrix. An angular d i f f e r e n c e of more than a maximum a l l o w a b l e 5 de v i a t ion f o r c e s r e o r i e n t a t i o n and r e c a l c u l a t i o n of the o r i e n t a t i o n m a t r i x . I n t e n s i t y standards ( u s u a l l y three r e f l e c t i o n s ) are monitored h o u r l y throughout data c o l l e c t i o n and are compared to the i n t e n s i t i e s of the same standards c o l l e c t e d at the beginning of the data s e t . A decrease of more than a s p e c i f i e d percentage (most o f t e n 25%) i n any one of the standard r e f l e c t i o n s ' i n t e n s i t y h a l t s the data c o l l e c t i o n . Determination of c e l l c o n s t a n t s Upon completion of the data c o l l e c t i o n , 25 r e f l e c t i o n s with r e l a t i v e l y high i n t e n s i t i e s and hig h theta v a l u e s are chosen from the data as the new set of r e f e r e n c e r e f l e c t i o n s . These are cen t e r e d and used i n determining a more a c c u r a t e o r i e n t a t i o n matrix. Theta angles are determined independent of the zero e r r o r of the d e t e c t o r by employing an omega scan at negative t h e t a - n e g a t i v e h k l . The d i f f e r e n c e i n the omega va l u e s f o r the p o s i t i v e and negative r e f l e c t i o n s y i e l d s an a c c u r a t e value f o r 29 when u and & are coupled i n a 1:2 angular r a t i o . F i n a l c e l l c o n stants are then determined by c o n s t r a i n e d l e a s t squares f i t to the sin© val u e s f o r the centered r e f e r e n c e r e f l e c t i o n s . Data r e d u c t i o n The data i s processed with a l o c a l l y w r i t t e n data r e d u c t i o n program (16); Lorentz and p o l a r i z a t i o n c o r r e c t i o n s are a p p l i e d ; s c a l i n g of the r e f l e c t i o n s sometimes f i n d s a p p l i c a t i o n such as in the case of i n t e n s i t y decay over the d u r a t i o n of data 6 c o l l e c t i o n ; and the d e t e r m i n a t i o n of observed r e f l e c t i o n s i s c a r r i e d out based on the c r i t e r i o n of l / * ( I ) being g r e a t e r than or equal to n, where n = any p o s i t i v e r e a l number; I = c(S - B), where c i s a s c a l e f a c t o r accounting f o r the above c o r r e c t i o n s , v a r y i n g scan speeds and the a t t e n u a t o r i f used, S i s the scan count and B i s the time-averaged background; a2 (I) = S + 2B + (z(S - B ) ) 2 , z being an a d d i t i o n a l f a c t o r which a l l o w s f o r i n s t r u m e n t a l i n s t a b i l i t y . The output from the data r e d u c t i o n c o n s i s t s of the r e f l e c t i o n s ' i n d i c e s , the t h e t a v a l u e s , and the c o r r e c t e d i n t e n s i t i e s along with t h e i r standard d e v i a t i o n s . At t h i s p o i n t , the data are ready f o r use i n the s t r u c t u r e s o l v i n g process and subsequent refinement of the s o l u t i o n . S o l u t i o n by d i r e c t methods The procedures and techniques employed i n determining the unobservable phases d i r e c t l y from the data are known c o l l e c t i v e l y as ' d i r e c t methods'. A b r i e f account of these methods i s deemed necessary f o r they were used e x c l u s i v e l y i n o b t a i n i n g the s o l u t i o n s to the s t r u c t u r e s presented in t h i s t h e s i s . The approach taken i n d i r e c t methods i s l a r g e l y s t a t i s t i c a l i n nature making frequent use of p r o b a b i l i t i e s and p r o b a b i l i t y d i s t r i b u t i o n s . For the s t a t i s t i c s to be v a l i d i t i s necessary to reduce a l l r e l a t i v e q u a n t i t i e s to an a b s o l u t e s c a l e s i n c e the a p r i o r i p r o b a b i l i t y d i s t r i b u t i o n s are based on assumptions, and c a l c u l a t i o n s u s i n g these assumptions. I t i s t h e r e f o r e , convenient i n the i n i t i a l stages of s o l v i n g any s t r u c t u r e to 7 remove the dependence of the observed s t r u c t u r e f a c t o r s F o ( r i ) , on atomic s c a t t e r i n g f a c t o r s (which i n t u r n depend on the s c a t t e r i n g angle and are a f f e c t e d by thermal v i b r a t i o n ) . T h i s i s done by d e f i n i n g normalized s t r u c t u r e f a c t o r s E ( h ) , where |E(n")| 2 = k 2 |Fo(n~) | 2 / { t E f j 2 } ; k i s a s c a l i n g f a c t o r r e q u i r e d to convert the r e l a t i v e Fo(ti) v a l u e s , d e r i v e d from the i n t e n s i t i e s , to a b s o l u t e q u a n t i t i e s based on the s c a t t e r i n g m a t e r i a l i n the u n i t c e l l , and c i s an i n t e g e r i n s e r t e d to account f o r symmetry inherent i n p a r t i c u l a r zones depending on the space group. These E-values, having no ©-dependence nor v i b r a t i o n a l component, correspond to s t r u c t u r e s d e r i v e d from a s t a t i o n a r y - p o i n t - a t o m model. One of the main advantages of using E's r a t h e r than F's i s that p r o b a b i l i t y e x p r e s s i o n s are s i m p l i f i e d . T h i s a r i s e s from the c o n s i d e r a t i o n that i f the atoms are randomly arranged i n the c e l l the p r o b a b i l i t y d i s t r i b u t i o n of E i s normal with a v a r i a n c e of u n i t y . The s t a t i s t i c a l p r o p e r t i e s of the E's are independent of the chemical composition and are u s e f u l i n d i s t i n g u i s h i n g between centrosymmetric and non-centrosymmetric space groups. The e x p e c t a t i o n value f o r |E(n")| 2 i s 1.000 by d e f i n i t i o n , r e g a r d l e s s of the space group symmetry. However, <|E(n~)|> i s 0.798 f o r c e n t r i c i n t e n s i t y d i s t r i b u t i o n s which u s u a l l y are c h a r a c t e r i s t i c of centrosymmetric space groups, whereas, an a c e n t r i c d i s t r i b u t i o n of i n t e n s i t i e s , c h a r a c t e r i s t i c of non- centrosymmetr i c space groups y i e l d s a <|E(n")|> value of 0.886. If the E - s t a t i s t i c s obtained from a s t r u c t u r e are such that space group assignment (with r e s p e c t to centrosymmetry) i s ambiguous, a f u r t h e r , more powerful s t a t i s t i c a l t e s t i s 8 a v a i l a b l e i n the form of the N ( z ) , or zero moment t e s t (10). In t h i s t e s t N(z) i s p l o t t e d a g a i n s t z, where N(z) i s the f r a c t i o n of r e f l e c t i o n s whose i n t e n s i t i e s , |E ( £ ) | 2 , are l e s s than or equal to a s p e c i f i e d f r a c t i o n , z, of the average i n t e n s i t y | E ( S ) | 2 . A comparison of the experimental d i s t r i b u t i o n over incremental values of z with the t h e o r e t i c a l N(z) cumulative p r o b a b i l i t y d i s t r i b u t i o n curves u s u a l l y p r o v i d e s the necessary i n f o r m a t i o n needed to d i s t i n g u i s h c e n t r i c from a c e n t r i c d i s t r i b u t i o n s . I t i s , however, important to remember that pseudo-symmetry i n the c e l l and point-group symmetry of p r o j e c t i o n s can have n o t i c e a b l e e f f e c t s on the above d i s t r i b u t i o n s and i t i s imperative, t h e r e f o r e , to c o n s i d e r any known molecular symmetry and probable molecular o r i e n t a t i o n i n the u n i t c e l l ( p o s s i b l y based on c r y s t a l h a b i t and/or c e l l parameters) before d e c i d i n g whether or not the space group has centrosymmetry. The next step toward s o l v i n g the s t r u c t u r e by d i r e c t methods i s to o b t a i n a l i s t i n g of a l l r e f l e c t i o n t r i p l e s s a t i s f y i n g the Sayre r e l a t i o n s h i p & = t. + ti-t (12). Such t r i p l e s , a l s o known as E 2 - r e l a t i o n s h i p s , are paramount in determining the phases of a l a r g e number of r e f l e c t i o n s knowing r e l a t i v e l y few phases i n i t i a l l y . The r e l a t i o n s h i p among the phases of the E 2's , *(lt) ̂  <0(It) + 0(fi-)t)> i s d e r i v e d from Sayre's equation (12), which expressed i n terms of normalized s t r u c t u r e f a c t o r s i s E(fT) = NV 2<E(it)E(ii-it)>, where < > means the average over a l l values of it and N i s the number of atoms in the c e l l . The symbol ~ i n the e x p r e s s i o n i n v o l v i n g the phases w i t h i n each E 2 , means 'probably equal t o ' . 9 In the case of centrosymmetric s t r u c t u r e s the phase of each r e f l e c t i o n i s e i t h e r 0 or u and corresponds to the assignment of ->- a (+) or (-) s i g n , r e s p e c t i v e l y to the magnitude |E(h)|. The p r o b a b i l i t y t h a t the s i g n of E(h) w i l l be +ve i s given by, P. = 1/2 + l/2tanh{N" 1/2 |E(h) | LE(k)E(h-k) } and the p r o b a b i l i t y of E(h) being -ve i s j u s t P. = 1 - P +. Sign i n d i c a t o r s of g r e a t e r than a p r o b a b i l i t y of 0.95 are u s u a l l y taken as c o r r e c t . As suggested above, a few phases must be known i n advance r e g a r d l e s s of the space group i n order to i n i t i a t e the phase determining o p e r a t i o n . Three and sometimes fewer r e f l e c t i o n s are as s i g n e d a r b i t r a r y phases at the s t a r t . These r e f l e c t i o n s are chosen a c c o r d i n g to s p e c i f i c r u l e s (which are space group dependent) to be o r i g i n d e t e r m i n i n g (17). An obvious requirement i n choosing these r e f l e c t i o n s i s that they enter i n t o as many E 2-combinations as p o s s i b l e . Other phases may have been determined ( p r i o r to t h i s p o i n t ) with a high degree of p r o b a b i l i t y by so c a l l e d E , - r e l a t i o n s h i p s , which are s p e c i a l cases of the more general I 2 - f o r m u l a and depend only the magnitude of the normalized s t r u c t u r e s f a c t o r s i n v o l v e d . In the case of non-centrosymmetric space groups an a d d i t i o n a l phase must be s p e c i f i e d i n order to d e f i n e the p o s i t i v e sense of the c o o r d i n a t e system. The phasing of the remaining bulk of r e f l e c t i o n s b e g i n s . Once the E 2 l i s t i n g i s exhausted using known and p r o b a b i l i t y determined phases there w i l l most l i k e l y remain some r e f l e c t i o n s which are as yet p h a s e l e s s . Some of these r e f l e c t i o n s are assigned symbols ( l e t t e r s ) f o r the phases, and 10 through the E 2 ' s i n which these r e f l e c t i o n s are i n v o l v e d simple mathematical r e l a t i o n s h i p s among the symbols can a r i s e . Because symbols are used f o r phases the method i s known as the 'Symbolic A d d i t i o n ' method (14). At the end of t h i s phase determining process the r e f l e c t i o n s which remain with symbol phases are permuted with values of 0 and ir i n the centrosymmetric case, and ±TT/4 and ±3ir/4 i n the non-centrosymmetr i c case thereby g e n e r a t i n g s e t s of phases corre s p o n d i n g to each permutation. The method d e s c r i b e d above f o r the d i r e c t d e t e r m i n a t i o n of phases from the magnitudes of the s t r u c t u r e f a c t o r s has been implemented i n many forms and one of the most widely used i s the FORTRAN IV w r i t t e n computer program MULTAN (18). The program d i f f e r s b a s i c a l l y i n one re s p e c t from the Symbolic A d d i t i o n method; MULTAN a s s i g n s e x p l i c i t v a l u e s to the phases of the base r e f l e c t i o n s which by the Symbolic A d d i t i o n method would have been represented by symbols. The advantage gained by employing phase values at the outset i s evident i n the s o l v i n g of non- centrosymmetr i c s t r u c t u r e s whereby the i n i t i a l phases (and subsequently determined approximate phases) are r e f i n e d i n an i t e r a t i v e manner by -the tangent formula, tan*(fi) = { I G [ s i n ( * ( f i - le) + *(lc)) ] } / { l G [ c o s U ( f i - l t ) + *(k"))]}, where G i s a f u n c t i o n of the E-values of the r e f l e c t i o n s t and fi-t. Each set of phases determined f o r a given permutation of the v a r i a b l e base phases i s assessed a c c o r d i n g to i t s i n t e r n a l c o n s i s t e n c y and the s t r u c t u r a l model i t r e p r e s e n t s . These assessments are q u a n t i f i e d and d i s p l a y e d as ' f i g u r e s of m e r i t ' . G e n e r a l l y , but not always, the set of phases y i e l d i n g the best f i g u r e s of merit c o n s t i t u t e s the s o l u t i o n , and these phases i n combination with the 11 magnitudes of the normalized s t r u c t u r e f a c t o r s a ct as c o e f f i c i e n t s i n a F o u r i e r s y n t h e s i s i n producing a t h r e e - dimensional e l e c t r o n d e n s i t y map r e f e r r e d t o as an E-map. An i n t e r p r e t a b l e E-map which makes chemical sense i s o b v i o u s l y the tru e t e s t of the c o r r e c t n e s s of a set of phases. Ref inement The refinement of the parameters f o r a l l s t r u c t u r e s f o l l o w i n g was accomplished by u t i l i z i n g f u l l matrix l e a s t squares procedures. The f u n c t i o n minimized throughout refinement was Ew(|Fo| - k | F c | ) 2 , where Fo and Fc are the observed and c a l c u l a t e d s t r u c t u r e f a c t o r s , k a s c a l i n g f a c t o r (where k i s now the r e c i p r o c a l of the k given on page 7), and w a weight a s s o c i a t e d with each r e f l e c t i o n . A u s e f u l i n d i c a t o r of the gene r a l progress of a p a r t i c u l a r s t r u c t u r a l refinement i s found i n the R-value, or the r e s i d u a l value which i s d e f i n e d as R = l | | F o | - k|Fc J|/E[Fo| . The weighted r e s i d u a l i s given by Rw = [Ew(|Fo| - k | Fc | ) 2/Ew | Fo | 2 ]''/ 2 and i s more c l o s e l y r e l a t e d to the f u n c t i o n minimized EwA2 (where A = |Fo| - k | F c | ) . There i s a v a r i e t y of weighting schemes a v a i l a b l e f o r use in the refinement. In the i n i t i a l stages, u n i t weights may be chosen to a c c e l e r a t e convergence; however, i n the f i n a l stages of the refinement the weights should r e f l e c t the accuracy of the dat a . Weights may be a b s o l u t e , d e r i v e d from the e r r o r s i n the i n t e n s i t i e s , or they may be r e l a t i v e , c a l c u l a t e d such that uniform averages over wA2 are achieved f o r ranges of Fo v a l u e s . For t h i s work a b s o l u t e weights were given by 1/tf 2(Fo), where 1 2 * 2 ( F o ) = d 2 ( I ) / ( 4 I ) , whereas, r e l a t i v e weights were c a l c u l a t e d from the polynomial (A + BFo + C F 0 2 + D F o 3 ) " 1 (19). S c a t t e r i n g f a c t o r s (f°) f o r a l l non-hydrogen atoms were taken from Cromer .and Mann (20) while those f o r hydrogen atoms were from r e f e r e n c e 21. The form of the s c a t t e r i n g f a c t o r s i n the refinement of atoms assumed to v i b r a t e i s o t r o p i c a l l y i s f = f °exp[-8n 2u 2 ( s i n © A ) 2 ] , where u"2" i s the mean-square displacement of the atom from i t s average p o s i t i o n . For atoms with a n i s o t r o p i c thermal v i b r a t i o n s f = f°exp[- 2 n 2 Z E U i j h i a | h ; j a j ]. In the Tables that f o l l o w , U i s o = U 2, and Ueq i s one t h i r d the t r a c e of the d i a g o n a l i z e d temperature f a c t o r ma t r i x . Photochemistry: 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 Research i n t o the s o l u t i o n photochemistry of the 4ap,5,8,8a0-tetrahydro-1,4-naphthoquinones was i n i t i a t e d i n an e f f o r t to determine t h e i r r e a c t i v i t i e s and to compare them with Chemical I n t r o d u c t i o n o 8 1 O 4a0,5,8,8ap-tetrahydro-1,4-naphthoquinone 13 s i m i l a r , known systems c o n t a i n i n g a -(CH 2)n- b r i d g e a c r o s s C(5) and C(8) (22,23). Whereas the l a t t e r systems were found to react v i a [2+2] i n t r a m o l e c u l a r c y c l o a d d i t i o n forming a cyclobutane r i n g with carbons 2, 3, 6 and 7, the tetrahydronaphthoquinones r e a c t e d by v a r i o u s hydrogen a b s t r a c t i o n processes (24,25). The observed photoproducts from a b s t r a c t i o n r e a c t i o n s r e s u l t e d from molecules and i n t e r m e d i a t e s which were c o n f o r m a t i o n a l l y l a b i l e i n s o l u t i o n . L i t t l e c o n t r o l over the p h o t o r e a c t i o n s c o u l d be e x e r c i s e d i n a medium a f f o r d i n g such freedom of motion, and t h e r e f o r e the r e s t r i c t i o n s o f f e r e d by a c r y s t a l l a t t i c e seemed a p p e a l i n g ; thus, entry was made i n t o the realm of s o l i d s t a t e photochemistry. I n t e r e s t i n g l y , a v a r i e t y of photoproducts r e s u l t e d from the i r r a d i a t i o n of v a r i o u s naphthoquinone d e r i v a t i v e s i n the s o l i d s t a t e (26). Although photoproducts from the s o l i d s t a t e r e a c t i o n s were i n v a r i a b l y observed in s o l u t i o n , the converse was not t r u e , f o r some of the s o l u t i o n products r e q u i r e d e x t e n s i v e c o n f o r m a t i o n a l rearrangements which were not p o s s i b l e i n the c o n f i n e s of the c r y s t a l l a t t i c e . In the s o l i d s t a t e , the main r e a c t i o n routes i d e n t i f i e d were i n i t i a t e d by one of four s t e p s : i ) i n t e r m o l e c u l a r [2+2] d i m e r i z a t i o n i n v o l v i n g C(2)=C(3) bonds, i i ) fi-H a b s t r a c t i o n by oxygen 1, i i i ) y-H a b s t r a c t i o n by carbon, or i v ) i n t r a m o l e c u l a r [2+2] c y c l o a d d i t i o n i n v o l v i n g C(1)=0(1) and C(6)=C(7) bonds. I t was observed that a h i e r a r c h y e x i s t e d 1 The symbol § has two d i f f e r e n t meanings in the t e x t : i ) i t may r e f e r to the c o n f i g u r a t i o n , as i n 4ap,5,8,8a^-tetrahydro..., or i i ) i t may r e f e r to the p o s i t i o n of attachment of one atom r e l a t i v e to another, as i n p-H a b s t r a c t i o n . The context of the sentence should remove any ambiguity. 14 among the i n i t i a t i n g steps i n which [2+2] i n t e r m o l e c u l a r p h o t o d i m e r i z a t i o n was the p r e f e r r e d r e a c t i o n i f the surroundings p e r m i t t e d i t ; the remainder of the above l i s t i s i n the order of the next most l i k e l y to l e a s t l i k e l y p r o c e s s . S o l i d s t a t e / s o l u t i o n photoproduct d i f f e r e n c e s hinged on the method of b i r a d i c a l c o l l a p s e f o l l o w i n g p-H or y-H a b s t r a c t i o n ; c o n f o r m a t i o n a l changes of the b i r a d i c a l s i n s o l u t i o n allowed f o r a g r e a t e r v a r i e t y of p r o d u c t s . From the c r y s t a l s t r u c t u r e a n a l y s i s , the p e r t i n e n t geometric parameters i n v o l v e d i n each of the s o l i d s t a t e r e a c t i o n s were d e r i v e d f o r comparison with i d e a l s i t u a t i o n s . For a b s t r a c t i o n r e a c t i o n s , the i d e a l geometry i s achieved when the a b s t r a c t i n g o r b i t a l i s d i r e c t e d at the a b s t r a c t a b l e atom and the d i s t a n c e over which a b s t r a c t i o n i s to take p l a c e does not exceed the van der Waals r a d i i sum f o r the atoms i n v o l v e d . For 0-H a b s t r a c t i o n by oxygen the o r b i t a l r e s p o n s i b l e f o r the a b s t r a c t i o n i s the non-bonding, p - l i k e o r b i t a l on the oxygen which l i e s i n the plane of the c a r b o n y l and i s d i r e c t e d normal to the C=0 bond. The r a d i i sum l i m i t f o r t h i s process i s 2.72 A (27). For convenience of c a l c u l a t i o n and comparison with other d e r i v a t i v e s , the p o s i t i o n of the 0-H with respect to the n- o r b i t a l can be c h a r a c t e r i z e d by three values ( F i g . 1): T q , the angular d e v i a t i o n between the 0 ( l ) . . . H a b v e c t o r and the mean plane through the c a r b o n y l group; A Q, the C ( 1 ) = 0 ( 1 ) . . . H a b s angle; and the 0 ( l ) . . . H a b d i s t a n c e . Optimum valu e s f o r rQ and A Q are 0° and 90°, r e s p e c t i v e l y (as a l l u d e d to above). S i m i l a r d e f i n i t i o n s are used to c h a r a c t e r i z e the y-H a b s t r a c t i o n - b y - c a r b o n process i n which the C(2) 2 p - o r b i t a l does 15 the a b s t r a c t i n g . In t h i s case, the mean plane c o n s i d e r e d i s the C(1), C(2), C(3), C(4) plane to which the 2 p - o r b i t a l i s pe r p e n d i c u l a r i n the ground s t a t e . Assuming that the r e a c t i v e e x c i t e d s t a t e has the same shape as the ground s t a t e , i d e a l c o n d i t i o n s f o r t h i s a b s t r a c t i o n process a r e : T c = 90°, which i s the angle between the C ( 2 ) . . . H a j j S v e c t o r and i t s p r o j e c t i o n onto the mean plane C ( 1 ) , . . . , C ( 4 ) ; A c = 90°, which i s the C(3)=C(2)...H ab S angle; and the a b s t r a c t i o n d i s t a n c e being l e s s than 2.90 A (27), the van der Waals r a d i i sum l i m i t f o r C and H. The [2+2] c y c l o a d d i t i o n r e a c t i o n s i n v o l v e 2 p - o r b i t a l s . Schmidt (28) has suggested that f o r such a r e a c t i o n to occur, the r e a c t i n g double bonds must be p a r a l l e l and separated by l e s s than 4.1 A. Indeed, f o r naphthoquinones undergoing t h i s r e a c t i o n , and those undergoing the a b s t r a c t i o n processes, a l l s a t i s f i e d the r e s p e c t i v e r e q u i s i t e geometries. Having s t u d i e d the e f f e c t s of s u b s t i t u e n t s and co n f o r m a t i o n a l changes on the p h o t o r e a c t i v i t y i n the Fi g u r e 1 D e f i n i t i o n s of r 0 and A Q. 16 naphthoquinone system, i t was of i n t e r e s t next, to compare the e f f e c t of a l t e r i n g the a c t i v e chromophore. What e f f e c t , i f any, would a r e d u c t i o n to an enone from an ene-dione chromophore have on the observed p h o t o r e a c t i o n s ? A study was i n i t i a t e d i n t o the 4ap,5,8,8a£-tetrahydro-1 - naphthoquin-4-ol system (29) ( F i g . 2). Members of t h i s s e r i e s were r e a d i l y a f f o r d e d by sodium borohydride r e d u c t i o n of the corresponding naphthoquinones. Both isomers are formed on r e d u c t i o n , but not n e c e s s a r i l y i n equal amounts s i n c e the r e a c t i o n s are governed c h i e f l y by s t e r i c approach and not by product development c o n t r o l . One isomer has the h y d r o x y l group ' a n t i ' , the other 'syn' to the bridgehead s u b s t i t u e n t s 2 and are o F i g u r e 2 Pro d u c t i o n of 4a$,5,8,8ap-tetrahydro-1-naphthoquin-4-ols. r e f e r r e d to as a- and p-hydroxy compounds, r e s p e c t i v e l y . The two isomers c r y s t a l l i z e i n d i s t i n c t conformations i n which the b u l k i e r OH group occupies the l e s s s t e r i c a l l y h indered pseudo- 2 The terms ' a n t i ' and 'syn' were d e l i b e r a t e l y chosen to d e s c r i b e the c o n f i g u r a t i o n of the h y d r o x y l group r e l a t i v e to the bridgehead s u b s t i t u e n t s to a v o i d c o n f u s i o n with the ' c i s ' - f u s e d r i n g j u n c t i o n . 17 e q u a t o r i a l p o s i t i o n . These conformations may i n t e r c o n v e r t by t w i s t i n g about the C(4a)-C(8a) br i d g e r e s u l t i n g i n a r i n g - f l i p ( F i g . 3). Both conformations can be d e s c r i b e d as a h a l f - c h a i r cyclohexene r i n g c i s - f u s e d to a h a l f - c h a i r cyclohexenone moiety. The s o l i d s t a t e photoproducts r e s u l t mainly from H(8) a b s t r a c t i o n by C(3) i n the 4p-ol d e r i v a t i v e s and from H(5) a b s t r a c t i o n by C(3) i n the 4a-ol d e r i v a t i v e s . In s o l u t i o n , however, a cage compound i s the major photoproduct (29,30) and r e s u l t s from a high energy conformer ( F i g . 3), i n t e r m e d i a t e between the 4 c - o l and 4p-ol conformations (and not a v a i l a b l e i n the c r y s t a l l a t t i c e ) which r e a c t s v i a i n t r a m o l e c u l a r [2+2] c y c l o a d d i t i o n a c r o s s the C(2)=C(3) and C(6)=C(7) double bonds. D e f i n i t i o n s r e l e v a n t to a b s t r a c t i o n geometries ( F i g . 4) are s i m i l a r to those in the naphthoquinone system; T i s the angle between the C(3)...H ^ v e c t o r and i t s p r o j e c t i o n onto the mean plane of the C(2)=C(3) double bond (C(1), C(2), C(3), C ( 4 ) ) ; A £ i s the H . .,.C(3)=C(2) an g l e . In t h i s case, i d e a l T and A 3 D S C C v a l u e s should be 90° i f the r e a c t i v e e x c i t e d s t a t e has the same shape as the ground s t a t e . S e v e r a l of the naphthoquinols d i s p l a y e d geometry resembling the above i n the s o l i d s t a t e , and most of these d e r i v a t i v e s r e a c t e d v i a H - a b s t r a c t i o n by carbon; the hexamethyl-40-ol d e r i v a t i v e , however, showed no r e a c t i v i t y i n the s o l i d s t a t e (30). Although t h i s was a t t r i b u t e d to the long C ( 3 ) . . . H a b s d i s t a n c e of 2.92 A which i s g r e a t e r than the van der Waals r a d i i sum of 2.90 A f o r C and H, i t was f e l t t h a t so sharp a c u t - o f f was not h i g h l y probable and that there must be an a d d i t i o n a l f a c t o r p r e v e n t i n g r e a c t i o n . Almost a l l of the 4G~O1S d i s p l a y e d the a d d i t i o n a l geometry s u i t a b l e f o r oxygen conformation t y p i c a l of 4 B - o l s ; R = H, R' = OH conformation t y p i c a l of 4 a - o l s ; R = OH, R 1 = H F i g u r e 3 Conformations i n naphthoquinols. a b s t r a c t i o n of a p-H, but t h i s r e a c t i o n was not observed. D e s p i t e the wealth of i n f o r m a t i o n gained from the study of the parent naphthoquinol and f i v e of i t s d e r i v a t i v e s , some p u z z l i n g f e a t u r e s s t i l l remained. Were there, indeed, w e l l - d e f i n e d l i m i t s f o r the a b s t r a c t i o n processes? What were the e f f e c t s of s u b s t i t u e n t s on molecular conformations and u l t i m a t e l y on r e a c t i v i t y ? Did the change of chromophore p r o h i b i t fi-H a b s t r a c t i o n by oxygen i n the naphthoquinols? Was hydrogen bonding a f a c t o r i n r e a c t i v i t y ? F i g u r e 4 D e f i n i t i o n s of T c and A c. 19 T h e s i s o u t l i n e The present work 3 d e s c r i b e d i n Part I of t h i s t h e s i s was undertaken i n an attempt to c l a r i f y the r o l e s of s u b s t i t u e n t s and conformations i n the s o l i d s t a t e p h o t o r e a c t i o n s . To determine the extent i n which topochemistry c o n t r o l s the s o l i d s t a t e r e a c t i o n s , comparisons are made with p h o t o r e a c t i o n s in s o l u t i o n . The f i r s t two chapters d e a l with m e t h y l - s u b s t i t u t e d 4o-ols and t h e i r p h o t o r e a c t i o n s i n the s o l i d s t a t e . At the end of the second chapter a c o n c l u s i o n i s reached r e g a r d i n g oxygen a b s t r a c t i o n r e a c t i o n s i n naphthoquinols. The f o l l o w i n g chapter i l l u s t r a t e s the b u i l d i n g of a s p e c i f i c molecule i n t o a p r e d i c t e d conformation based on the s t r u c t u r a l foundation l a i d by p r e v i o u s l y determined naphthoquinol s t r u c t u r e s . In a d d i t i o n to t h i s example of ' c r y s t a l e n g i n e e r i n g ' , a s t r u c t u r a l comparison i s made with the d e r i v a t i v e s i n the f i r s t two chapters and with the parent naphthoquinol from which they were d e r i v e d . Chapter IV i n c l u d e s a d e s c r i p t i o n of the f u l l y reduced naphthoquinone, namely the 1o,4o-diol ( F i g . 5). Though photochemically i n e r t (at the wavelength of i n t e r e s t f o r naphthoquinols) i t i s very c l o s e l y r e l a t e d i n s t r u c t u r e to the other d e r i v a t i v e s i n Part I. Some s t r u c t u r a l comparisons are made i l l u s t r a t i n g t h i s p o i n t . 3 The p r e p a r a t i v e work ( i n c l u d i n g c r y s t a l l i z a t i o n s ) and photochemistry of a l l compounds d i s c u s s e d i n t h i s t h e s i s , unless otherwise s t a t e d , were c a r r i e d out by W. K. Appel, D. Herbert, Z. Q. J i a n g , J . R. S c h e f f e r , L. Walsh and Y. F. Wong. 20 F i g u r e 5 R e l a t i o n s h i p of the d i o l to naphthoquinones and naphthoquinols. The i n i t i a l i n t e r e s t i n the s t r u c t u r e , however, arose from an u n s u c c e s s f u l attempt to c h a r a c t e r i z e the s t r u c t u r e i n the s o l i d s t a t e by 13C-NMR. The second Part of t h i s t h e s i s i s devoted to'unusual products whose p r e c u r s o r s are e i t h e r naphthoquinones, naphthoquinols or d e r i v a t i v e s t h e r e o f . Chapter V h i g h l i g h t s a t w i s t a n e - l i k e (31) s t r u c t u r e ( l a t e r r e f e r r e d to as a 'twistenone') which was produced i n an a p p r e c i a b l e q u a n t i t y f o l l o w i n g a minor m o d i f i c a t i o n i n the method of p h o t o l y s i s of u n s u b s t i t u t e d naphthoquinone i n s o l u t i o n . I r r a d i a t i o n of the 6,7-dimethyl-naphthoquinone by the same method that produced the twistenone y i e l d e d a new product which w i l l be c a l l e d X, unseen i n p r e v i o u s s t u d i e s and as yet u n c h a r a c t e r i z e d . Chapter VI goes on to d i s c u s s the s t r u c t u r e d e t e r m i n a t i o n of the r - l a c t o n e r e s u l t i n g from the t h e r m o l y s i s of X. U n f o r t u n a t e l y , t h i s s t r u c t u r e d i d not provide as many c l u e s to the i d e n t i t y of X as was hoped i t would. Treatment of the heptamethyl-40-ol (whose s t r u c t u r e i s d e s c r i b e d i n Chapter I I I , Part I) with a c e t i c anhydride and z i n c c h l o r i d e r e s u l t s i n a t r i c y c l i c methylene ketone which upon i r r a d i a t i o n undergoes a rearrangement y i e l d i n g the s t r u c t u r e 21 d i s c u s s e d i n Chapter V I I . F i n a l l y , Chapter VIII d e s c r i b e s the s t r u c t u r e of a d e r i v a t i v e of the cage compound produced i n s o l u t i o n by p h o t o l y s i s of the hexamethyl-4c-ol (30). The d e r i v a t i v e d i s c u s s e d r e s u l t e d from u n s u c c e s s f u l e f f o r t s to perform an i n t r a m o l e c u l a r p i n a c o l i z a t i o n of the o x i d i z e d cage compound. Schematic of the T h e s i s Layout Chapters I , I I , I I I Chapter IV Unusual r e a c t i o n products Chapters V, VI Chapters V I I , V I I I 22 PART I 23 CHAPTER I 2,3,6,7-TETRAMETHYL-4ap,5,8,8ap-TETRAHYDR0- 1-NAPHTH0QUIN-4a-0L 24 I n t r o d u c t i o n The t e t r a m e t h y l d e r i v a t i v e d i s c u s s e d i n t h i s chapter i s the f i r s t of four t e t r a h y d r o n a p h t h o q u i n o l d e r i v a t i v e s , with v a r i o u s methyl s u b s t i t u t i o n p a t t e r n s , presented i n Part I. The s t r u c t u r e i s d e s c r i b e d with r e s p e c t to i t s conformation and the g e o m e t r i c a l parameters important i n the s o l i d s t a t e photochemical process. Experimental The 2,3,6,7-tetramethyl-4ap,5,8,8a£-tetrahydro-1-naphtho- q u i n - 4 c ~ o l 1 was prepared by the same gen e r a l r e a c t i o n scheme used i n o b t a i n i n g s i m i l a r naphthoquinols (29), namely by reducing the a p p r o p r i a t e D i e l s - A l d e r adduct with sodium borohydride. In the present case the thermal r e a c t i o n between 2,3-dimethyl-p-benzoquinone and 2,3-dimethyl-1,3-butadiene y i e l d e d the r e q u i r e d adduct (I) ( F i g u r e 6). The reduced adducts, (II) and ( I I I ) , were separated. V a r i o u s attempts were made at r e c r y s t a l l i z i n g ( I I I ) by slow e v a p o r a t i o n and, although most of the s o l v e n t systems a f f o r d e d c r y s t a l s , none were s u i t a b l e f o r s t r u c t u r a l a n a l y s i s . For example, benzene s o l u t i o n s gave t i n y diamond shaped p l a t e s with the longest dimension being only 0.1 mm; c r y s t a l s from ethanol/acetone s o l u t i o n s were f a i r l y l a r g e but upon i n s p e c t i o n under a p o l a r i z i n g microscope they were found to be twinned — a c o n d i t i o n wherein two c r y s t a l s are 1 IUPAC name: 4c-hydroxy-2,3,6,7-tetramethyl-4a*,5,8,8ap- tetrahydro-1(4H)-naphthalenone 25 intergrown i n such a way that the c r y s t a l l o g r a p h i c d i r e c t i o n s of one are r e l a t e d to the c o r r e s p o n d i n g d i r e c t i o n s of the second by e i t h e r t wo-fold or m i r r o r symmetry (and l e s s f r e q u e n t l y by a 3-, 4- or 6 - f o l d a x i s , or cen t e r of symmetry). Other systems i n v o l v i n g hexane and acetone were t r i e d , but to no a v a i l . However, c r y s t a l s grown from ethanol/petroleum ether s o l u t i o n s appeared s u i t a b l e f o r d i f f r a c t i o n study and hence one of these was mounted f o r photographs and subsequent data c o l l e c t i o n . The c r y s t a l employed measured 0.3 x 0.6 x 0.4 mm3 and was t a b u l a r i n h a b i t . F i g u r e 6 P r e p a r a t i v e r e a c t i o n scheme l e a d i n g to 2,3,6,7-tetramethyl-4a£,5,8,8a0-tetrahydro- 1-naphthoquin-40-ol ( I I ) and the isomeric 4o~ol ( I I I ) . P r e l i m i n a r y Weissenberg and p r e c e s s i o n photographs were taken i n an attempt to a s c e r t a i n the space group. The f i l m s r e v e a l e d the absence c o n d i t i o n s hO^, 1 = 2n + 1 and h k l , h + k = 2n + 1 which are c h a r a c t e r i s t i c of the two space groups C2/c and 26 Cc. A d e n s i t y c a l c u l a t i o n based on a u n i t c e l l volume of © approximately 1250 A 3 (from the a x i a l measurements on the photographs) i n d i c a t e d t hat four molecules were present i n the u n i t c e l l . C r y s t a l d ata: C, 4H 2o02, MW = 220.31, monoclinic a = 13.898(3), b = 5.228(1), c = 17.316(3) A, * = 97.442(7)°, V = 1247.7(5) A 3, Z = 4, D c= 1.1728 g cm" 3, D 0= 1.174 g cm" 3, ^(MoKo) = 0.714 cm - 1, X = 0.71073 A, space group C2/c, from absences and s t r u c t u r e a n a l y s i s . The c r y s t a l was mounted i n a g e n e r a l o r i e n t a t i o n on an Enraf-Nonius CAD4 d i f f T a c t o m e t e r . C e l l c o n s t a n t s and an o r i e n t a t i o n matrix were determined from the s e t t i n g angles f o r 25 centered r e f l e c t i o n s . A Delaunay r e d u c t i o n program p r o v i d e d the t r a n s f o r m a t i o n matrix r e q u i r e d to convert the p r i m i t i v e c e l l found by the CAD4 to the corresponding C-centered c e l l i n d i c a t e d on the photographs. Data were c o l l e c t e d i n the t h e t a range 0.0-27.5 degrees (minimum i n t e r p l a n a r spacing of 0.77 A) using g r a p h i t e monochromatized Mo r a d i a t i o n with omega scan speeds of 2.01- 10.06 deg m i n - 1 . From an a n a l y s i s of v a r i o u s peak p r o f i l e s , the best scan type was determined to be an u - 2 ( l / 6 ) e scan with an u- scan angle of (1.30 + 0.35tane) degrees (each scan being extended by 25% on both s i d e s f o r background measurement). A v a r i a b l e h o r i z o n t a l a p e r t u r e width of (2.00 + 1.00tane) mm was employed and the v e r t i c a l a p e r t u r e was f i x e d at 4 mm. C r y s t a l o r i e n t a t i o n checks were performed on three 27 re f e r e n c e r e f l e c t i o n s a f t e r every 100 r e f l e c t i o n s c o l l e c t e d . The i n t e n s i t i e s of three check r e f l e c t i o n s , which were monitored h o u r l y throughout data c o l l e c t i o n , were found to decay by not more than 0.3%. Lorentz and p o l a r i z a t i o n c o r r e c t i o n s were a p p l i e d i n the usual manner to the 1435 r e f l e c t i o n s c o l l e c t e d , of which 61.9% (888) had I > 3tf(I) (where <r 2(I) = S + 2B + (0.04(S - B ) ) 2 , S = scan count and B = time-averaged background). S o l u t i o n and Refinement A comparison of the average E-values with t h e i r e x p e c t a t i o n v a l u e s i n d i c a t e d a c e n t r i c d i s t r i b u t i o n of i n t e n s i t i e s . Furthermore, the zero moment t e s t (10) showed a curve ( f o r a l l data) very c l o s e l y resembling the t h e o r e t i c a l c e n t r i c d i s t r i b u t i o n p l o t . D e s p i t e t h i s strong suggestion of a centrosymmetric s t r u c t u r e the f a c t remained that the molecule was asymmetric and there were only four such molecules i n the u n i t c e l l (based on d e n s i t y ) . However, the approximate two-fold molecular symmetry may have been the cause of the c e n t r i c d i s t r i b u t i o n and on t h i s b a s i s an attempt was made to sol v e the s t r u c t u r e i n the non-centrosymmetric space group, Cc. One hundred s i x t y - f o u r E's with magnitudes g r e a t e r than 1.6 were input to MULTAN. The only phase determined by the I,- r e l a t i o n s h i p had an i n d i c a t e d p r o b a b i l i t y of 1.00 with 30 c o n t r i b u t o r s . O r i g i n d etermining r e f l e c t i o n s and one r e q u i r e d to d e f i n e the p o s i t i v e sense of the b - a x i s were chosen a c c o r d i n g to the r u l e s governed by the space group symmetry. The r e s u l t of 28 the phase determining process y i e l d e d 16 s e t s of phases of which only 4 were independent. Although there was no out s t a n d i n g s o l u t i o n , the set with the h i g h e s t f i g u r e of merit gave an i n t e r p r e t a b l e E-map (presented i n F i g u r e 7) which showed two fused six-membered r i n g s with s u b s t i t u e n t s at a l l but the bridgehead carbons. Peaks 10, 15 16 and 17 were a l l l o c a t e d i n p o s i t i o n s , r e l a t i v e to the r i n g , which were p o s s i b l e oxygen l o c a t i o n s . However, mass s p e c t r a l and IR data i n d i c a t e d only two oxygens i n the molecule ( F i g . 6) and t h e i r p o s i t i o n s were para- to each o t h e r . A f u r t h e r d i s t u r b i n g aspect, evident on the E- map, was the r e l a t i v e l y low height of the those peaks which were p o s s i b l y due to oxygens. Peak h e i g h t s which are d i r e c t l y p r o p o r t i o n a l to the e l e c t r o n d e n s i t y at the peak p o s i t i o n s are presumed a p r i o r i to be s l i g h t l y higher f o r oxygen than carbon atoms. The presence of four small peaks at p o s i t i o n s 10, 15, 16 and 17 i n s t e a d of two r e l a t i v e l y l a r g e peaks at 10 and 17, or 15 and 16 warned of the p o s s i b i l i t y of p a r t i a l occupation of these s i t e s by oxygen atoms, i..e. a d i s o r d e r e d s t r u c t u r e . Based on the asymmetry of the molecule, f u l l matrix l e a s t squares refinement of the s t r u c t u r a l parameters was i n i t i a t e d i n the non-centrosymmetric space group C£ with oxygens given the c o o r d i n a t e s of peaks 10 and 17 from the E-map. Six c y c l e s of refinement of 14 carbon and 2 oxygen atoms with a n i s o t r o p i c thermal parameters l e d to the r e s i d u a l index R, of 0.17. Furth e r c y c l i n g produced no s i g n i f i c a n t changes i n the parameters. The l a r g e degree of c o r r e l a t i o n between parameters of the cyclohexenone moiety and those of the cyclohexene p a r t of the molecule suggested that the asymmetric u n i t c o n s i s t e d of l e s s 29 is 17 10 F i g u r e 7 E-map; p r o j e c t i o n onto l e a s t squares plane through e l e c t r o n d e n s i t y peaks. Lowest number corresponds to p o s i t i o n of h i g h e s t d e n s i t y . than one molecule. A d i f f e r e n c e - F o u r i e r map i n d i c a t e d excess d e n s i t y peaks of 2-3 e/A 3 w i t h i n bonding d i s t a n c e s of C(5) and C ( 8 ) . Combined with the l a r g e magnitude of the temperature f a c t o r s of the two oxygens, these excess d e n s i t y peaks suggested a d i s o r d e r e d s t r u c t u r e whereby the molecule appears as two, fused cyclohexenone m o i e t i e s . Refinement proceeded i n the centrosymmetric space group C2/c with the molecule l y i n g on the two-fold r o t a t i o n a x i s . Oxygen atoms were i n c l u d e d i n i t i a l l y with i s o t r o p i c thermal parameters and at 50% occupancy, thus a l l o w i n g f o r the r o t a t i o n a l d i s o r d e r . Ten hydrogens were l o c a t e d from a d i f f e r e n c e - F o u r i e r map, while those on C(8) and 0(4) were not found due to the nature of the d i s o r d e r . In the l a t t e r stages, a l l non-hydrogen atoms were r e f i n e d with a n i s o t r o p i c temperature f a c t o r s whereas, the hydrogen atoms were i n c l u d e d with i s o t r o p i c thermal parameters. The oxygen atoms and the two hydrogen atoms at t a c h e d to C(5) 30 were h e l d at f i f t y per cent occupancy. The s t r u c t u r e converged at R = 0.058 and Rw = 0.078 f o r the 888 r e f l e c t i o n s with I £ 3tf(I); f o r the complete data set R = 0.088 and Rw = 0.078. The f i n a l d i f f e r e n c e s y n t h e s i s r e v e a l e d two peaks (0.208,0.231,0.245) and (0.179,0.131,0.271) of magnitudes 0.479 and 0.508 e/A 3, r e s p e c t i v e l y , i n the region of 0 ( 4 ) . However, n e i t h e r of these can be d i r e c t l y a t t r i b u t e d to the missing hydrogen, H(04), i n view of the poor bonding geometry they r e q u i r e at 0(4) and the s p a t i a l p r o x i m i t y to that atom. The l a r g e s t peak on the d i f f e r e n c e map had c o o r d i n a t e s (0.030,0.248,0.534) and a magnitude of 0.516 e/A 3. The mean and maximum parameter s h i f t s on the f i n a l c y c l e were 0.037 and 0.203*, r e s p e c t i v e l y . The standard d e v i a t i o n of an o b s e r v a t i o n of u n i t weight was 1.0017. R e f l e c t i o n s f o r which I < 3*(I) were c l a s s i f i e d as unobserved and not used i n the refinement. Observed r e f l e c t i o n s were a s s i g n e d weights c a l c u l a t e d from the p o l y n o m i a l , w = (A + BFo + CFo 2 + D F o 3 ) " 1 , where A = 0.3385, B = 0.02351, C = 0.002002 and D = 0.000097. T h i s gave uniform averages of w(|Fo| - k j F c | ) 2 over ranges of Fo. F i n a l p o s i t i o n a l and thermal parameters are presented i n Table I and a n i s o t r o p i c temperature f a c t o r s f o r the non-hydrogen atoms are given i n Table I I . Di s c u s s i o n The s t r u c t u r e c o n s i s t s of molecules w e l l - s e p a r a t e d along the c - a x i s with the c l o s e s t non-hydrogen approach being g r e a t e r than 3.5 A i n that d i r e c t i o n . There are two p o s s i b l e 31 Table I F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10 5, C(31) and 0 ( 1 ) ' x 10", H x 10 3) and i s o t r o p i c thermal parameters (U x 10 3 A 2) with estimated standard d e v i a t i o n s i n parentheses Atom 2 X 1 z Ueq/Uiso C O ) -4646(16) -1559(41) 32373(12) 52 C(2) 4666(16) -7399(37) 37272(11) 52 C(21) 3947(27) -26259(60) 4374906) 73 C(3) 12901(16) 3987(45) 35893(12) 57 C(31 ) 2248( 3) -95(10) 4084( 2) 96 C(4) 1 3402( 16) 22347(47) 29261(13) 58 C(8a) -4660(14) • 21 141(37) 26932(11) 48 0 ( 1 ) ' - 1157( 3) -1380(11) 3362( 3) 93 0(4) ' 21719(22) 20315(60) 25989(20) 64 H1 (21 ) 56( 3) -196( 7) 482( 2) 103(11) H2(21) 1 ( 3) -402( 8) 421 ( 3) 138(15) H3(21) 98( 4) -362( 9) 449( 3) 160(18) H1(31 ) 2 1 8 ( 3) -15( 9) 458( 3) 129(14) H2(31 ) 262( 4) -176(11 ) 409( 3) 181(22) H3(31) 266( 4) 110(10) 399( 3) 163(20) H(4) 1 42( 2) 392( 6) 3 1 4 ( 2) 88( 9) H1 (5) ' 68( 4) - 182( 9) 21 1 ( 3) 5 8 0 2 ) H2(5)' 99( 4) 5(11) 1 48 ( 3) 59(16) H(8a) -45( 2) 363( 5) 302( 1 ) 56( 6) 2 Primed (') atoms are at p o s i t i o n s of 50% occupancy 32 Table II o F i n a l a n i s o t r o p i c thermal parameters ( U i j X 10* A 2) and t h e i r estimated standard d e v i a t i o n s Atom Ui i y 2 2 U 3 3 U12 U 1 3 U 2 3 c(i) 521(12) 536(12) 532(11) -37( 9) 141( 9) 14(10) C(2) 642(13) 487( 1 1 ) 445(10) 2( 9) 77( 9) 17( 9) C(21 ) 993(22) 718(17) 479(13) -10(16) 109(12) 97(13) C(3) 563(13) 641(13) 494(11) -6(10) -8( 9) -3(10) C(31 ) 678(19) 1407(34) 720(19) -70(21) -148(14) 218(20) C(4) 52*6(1 3) 591(13) 611(12) -123( 9) 63(10) 11(11) C(8a) 516(12) 411(10) 50-9(10) 39( 8) 71 ( 8) -77( 9) 0(1 )' 619(24) 1138(36) 1027(32) -313(23) 105(21) 232(28) 0(4) ' 530(18) 701(19) 719(19) -39(14) 184(14) -3906) 33 0 i n t e r m o l e c u l a r 0...0 c o n t a c t d i s t a n c e s l e s s than 3 A. These c o n t a c t s can occur between the hydroxyl oxygen atom of one molecule and that of the c a r b o n y l i n the adjacent molecule, r e l a t e d by the c e n t e r i n g c o n d i t i o n , or between the same hydroxyl oxygen and the two-fold symmetry r e l a t e d oxygen i n the neighb o r i n g centered molecule. The 0(4)(x,y,z)..,0(1)(1/2+x,1/2- y,z) d i s t a n c e of 2.652(5) A suggests that hydrogen bonds l i n k molecules i n the [110] and [1 TO] d i r e c t i o n s . However, the 0(4) (x,y,-z) .. .0(4) (1/2-x, 1/2+y, 1/2-z) d i s t a n c e of 2.804(4) A suggests hydrogen bonding takes p l a c e between d i s o r d e r e d molecules. The above i n t e r m o l e c u l a r d i s t a n c e s are c o n s i s t e n t with the o b s e r v a t i o n that the c r y s t a l c l e a v e s e a s i l y p a r a l l e l to the (001) f a c e . D i s o r d e r i n the s t r u c t u r e , assumed to be 50:50, r e s u l t s - i n an apparent two-fold symmetry a x i s through the molecule. T h i s d i s o r d e r may be r a t i o n a l i z e d on the b a s i s that there appears to be l i t t l e s t e r e o c h e m i c a l hindrance p r e v e n t i n g the two molecular o r i e n t a t i o n s from c o - e x i s t i n g i n the same c r y s t a l , p r o v i d e d that alignment f o r hydrogen bonding i s maintained. The d i s o r d e r a r i s e s from packing arrangements i n which s l a b s p a r a l l e l to (001) c o n t a i n molecules of two types, A and B (where A and B are r e l a t e d by 180 degrees r o t a t i o n about b ) . Two kinds of hydrogen bonding are p o s s i b l e w i t h i n the s l a b s . They j o i n molecules i n the sequence A...A (or B...B) and A...B (or B...A). The bonds l i n k i n g molecules of s i m i l a r type are 0(4)(x,y,z)-H...0(1)(1/2+x,1/2-y,z) i n t e r a c t i o n s whereas molecules of d i f f e r e n t types are j o i n e d by 0 ( 4 ) ( x , y , z ) - H...0(4)(1/2-x,1/2+y,1/2-z) hydrogen bonds. There are s e v e r a l 34 packing arrangements c o n s i s t e n t with the dual composition and a v a i l a b l e hydrogen bonding w i t h i n each s l a b , and s i n c e packing f o r c e s are a major i n f l u e n c e on the c r y s t a l energy, the arrangements l e a d i n g to hydrogen bonding networks l i n k i n g the maximum number of molecules w i t h i n the s l a b s y i e l d the most probable s t r u c t u r e . F i g u r e 8 shows a s t e r e o s c o p i c drawing of the contents of the u n i t c e l l with C(4) l a b e l l e d by i t s a d j o i n i n g hydrogen. The molecules adopt a conformation which c o n s i s t s of a h a l f - c h a i r cyclohexene r i n g c i s - f u s e d to a second h a l f - c h a i r cyclohexenone F i g u r e 8 Stereo diagram of the molecular packing of type A molecules viewed approximately down b. moiety ( F i g . 9) s i m i l a r to p r e v i o u s l y s t u d i e d naphthoquinols (32). In comparison with accepted v a l u e s (33), the mean bond lengths are found to be s l i g h t l y s m a l l e r , with d i s t a n c e s of 35 1.524 A f o r C ( s p 3 ) - C ( s p 3 ) and 1.504 A f o r C ( s p 3 ) - C ( s p 2 ) . Carbon to hydrogen bond lengths g e n e r a l l y do not d e v i a t e s i g n i f i c a n t l y from the accepted v a l u e s . Bond angles are normal and are given i n Tables III and IV along with bond l e n g t h s . Some r i n g s t r a i n , i n d i c a t e d by a C(4)-C(3)-C(2)-C(1) t o r s i o n angle of -2.3° (Table F i g u r e 9 Stereo diagram of 2,3,6,7-tetramethyl- 4ap,5,8,8ap-tetrahydro-1-naphthoquin-4c-ol V) and compounded by an 0(1)-C(1)-C(2)-C(3) t o r s i o n angle of 175.0°, r e s u l t s i n the c a r b o n y l oxygen l y i n g 0.1 A above the mean plane through the former four atoms and C(1) l y i n g 0.005 A below the same mean plane. The molecule, e x h i b i t i n g the same conformation as other naphthoquin-4o~ol d e r i v a t i v e s i n the s e r i e s i s g e o m e t r i c a l l y s u i t e d to H(5) a b s t r a c t i o n by the p-carbon, C ( 3 ) , upon photochemical e x c i t a t i o n . The C(3)...H1(5) d i s t a n c e of 2.84(5) A i s l e s s than the van der Waals c o n t a c t d i s t a n c e of 2.90 A. Other 36 Table I I I Bond l e n g t h s 3 (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C O ) -C(2) 1 .484(3) C(3) -C(31 ) 1 .510(4) C O ) -C(8a) 1 .515(3) C(3) -C(4) 1 .505(3) C O ) -0(1 ) 1 .199(4) C(4) -0(4) 1 .356(4) C(2) -C(21) 1 .506(3) C(4) -C(8a)" 1 .514(3) C(2) -C(3) 1 .339(3) C(8a) - C ( 8 a ) n 1 .533(4) Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle • Bonds Angle C(2) -CO ) -C(8a) 116. 6(2) C(31 ) -C(3) -C(4) 114.7(2) C(2) -CO) -0(1 ) 116. 6(3) C(3) -C(4) -0(4) 113.3(2) C(8a) -CO ) -0(1 ) 126. 5(3) C(3) -C(4) -C(8a)" 113.7(2) C O ) -C(2) -C(21) 115. 0(2) 0(4) -C(4) -C(8a)" 110.5(2) C O ) -C(2) -C(3) 120. 6(2) C O ) -C(8a) - C ( 8 a ) n 109.8(1) C(21 ) -C(2) -C(3) 124. 4(2) C O ) -C(8a) -C( 4 ) " 1 14.2(2) C(2) -C(3) -C(31) 122. 3(3) C(8a)' "-C(8a) -C( 4 ) " 109.7(2) C(2) -C(3) -C(4) 123. 0(2) 3 Double primes (") denote symmetry r e l a t e d atoms. 37 Table IV « Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(21 ) -H1(21) 0. 86(4) C(31 ) -H3(31) 0. 88(5) C(21 ) -H2(21) 0. 93(4) C(4) -H(4) 0. 96(3) C(21 ) -H3(21) 0. 96(5) C(8a) -H(8a) 0. 98(2) C(31 ) -H1(31) 0. 88(5) C ( 1 ) " -H1(5) 1 . 08(5) C(31 ) -H2(31) 1. 01 (6) C(1 )" -H2(5) 0. 93(6) Bond angles i n v o l v i n g hydrogen atoms (deg) with e s t imated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -C(21 ) -HI(21) 112(2) C(3) -C(4) -H(4) 108(2) C(2) -C(21 ) -H2(21) 112(3) 0(4) -C(4) -H(4) 99(2) C(2) -C(21 ) -H3(21) 112(3) H(4) -C(4) -C(Ba)' ' 111(2) H1 (21 )-C(21 ) -H2(21) 133(4) C O ) -C(8a) -H(8a) 106(1) H1 (21 )-C(21 ) -H3(21) 84(3) C(8a)" -C(8a) -H(8a) 107(1) H2(21)- C(21 ) -H3(21) 94(3) C ( 4 ) " -C(8a) -H(8a) 109(1) C(3) - C(31 ) -H1(31) 111(3) C ( 2 ) n -CO )" -HI(5) 108(2) C(3) - C(31 ) -H2(31) 124(3) C(2)" - C O ) " -H2(5) 114(3) C(3) -•C(31 ) -H3(31) 109(3) C(8a)" -CO )" -H1(5) 108(3) H1(31 )--C(31 ) -H2(31) 95(4) C ( 8 a ) n -CO )" -H2(5) 107(4) H1(31 )--C(31 ) -H3(31) 112(4) H1 (5) - C O ) " -H2(5) 102(4) H2(31 )--C(31 ) -H3(31) 106(4) 38 p e r t i n e n t geometric f a c t o r s c o n s i d e r e d i n the a b s t r a c t i o n process i n c l u d e the angle C(2)-C(3)...H1(5), A , and the angle subtended by the C(3) to H1(5) v e c t o r and i t s p r o j e c t i o n on the plane of the carbon-carbon double bond, T c ; these angles were found to be 79.5 and 53.5 degrees, r e s p e c t i v e l y . These values are comparable to those found i n s i m i l a r s u b s t i t u t e d naphthoquinols that were shown to undergo H - a b s t r a c t i o n by the p-enone carbon (30,32). Photochemical r e s u l t s of the present compound i n d i c a t e c l e a r l y that H 1 ( 5 ) - a b s t r a c t i o n by C(3) i s the major process t a k i n g p l a c e . Whereas the molecular geometry i s a l s o f a v o r a b l e to H(8) a b s t r a c t i o n by 0(1) as i n naphthoquinone d e r i v a t i v e s (26,34), t h i s r e a c t i o n was not observed i n the present compound. i Table V T o r s i o n angles (deg) with estimated standard d e v i a t i o n s i n parentheses Atoms Value C(8a) -C(1) -C(2) -C(21) 1 67 .6(2) C(8a) -C(1 ) -C(2) -C(3) -1 1 .5(3) 0(1 ) -C(1) -C(2) -C(21) -5 .9(5) 0(1) -C(1 ) -C(2) -C(3) 1 75 .0(4) C(2) -C(1 ) -C(8a) -C(8a)" 42 .0(3) C(2) -C(1 ) -C(8a) -C( 4 ) " 165 .6(2) 0(1) -C(1) -C(8a) -C(8a)" -1 45 .2(5) 0(1 ) -C(1) -C(8a) -C( 4 ) " -21 .6(5) C(1 ) -C(2) -C(3) -C(31) 178 .6(3) C(1) -C(2) -C(3) -C(4) -2 .3(3) C(21 ) -C(2) -C(3) -C(31) 0 .4(4) C(21 ) -•C(2) -C(3) -C(4) 178 .7(2) C(2) -C(3) -C(4) -0(4) -143 .5(3) C(2) -C(3) -C(4) -C(8a)" -16 .3(3) C(31 ) -C(3) -C(4) -0(4) 35 .7(4) C(31 ) -C(3) -C(4) -C(8a)" 162 .9(3) C(3) -C(4) -C(8a) "-C(8a) 46 .5(2) C(3) -C(4) -C(8a) M - C ( 1 ) " -77 . 1(2) 0(4) -C(4) -C(8a) "-C(8a) 175 .2(2) 0(4) -C(4) -C(8a) "-C(1)" 51 .5(3) C(1 ) -C(8a) -C(8a)"-C(4) -58 .9(2) C(1) -C(8a) -C(8a) "-C(1)" 67 .3(3) Table V (continued) C(4)" -C(8a) - C ( 8 a ) r -C(4) 174.9(2) C ( 4 ) n -C(8a) - C ( 8 a ) r - C ( 1 ) " -58.9(2) C(2) -C(1 ) -C(8a) -H(8a) -73.8(13) 0(1) -C(1) -C(8a) -H(8a) 99.0(14) C(1) -C(2) -C(21) -H1(21) -118(3) C(1 ) -C(2) -C(21) -H2(21) 44(3) C(1) -C(2) -C(21) -H3(21) 149(3) C(3) -C(2) -C(21) -H1(21) 61(3) C(3) -C(2) -C(21) -H2(21) -136(3) C(3) • -C(2) -C(21 ) -H3(21) -32(3) C(2) -C(3) -C(31) -H1(31) -42(3) C(2) -C(3) -C(31) -H2(31) 70(4) C(2) -C(3) -C(31) -H3(31) -165(4) C(4) -C(3) -C(31) -H1(31) 139(3) C(4) -C(3) -C(31) -H2(31) -109(4) C(4) -C(3) -C(31) -H3(31) 16(4) C(2) -C(3) -C(4) -H(4) 107(2) C(31 ) -C(3) -C(4) -H(4) -74(2) C(3) -C(4) -C(8a) n - H ( 8 a ) " 164.2(13) 0(4) -C(4) -C(8a) **-H(8a) " -67.1(14) H(4) -C(4) -C(8a) "-C(8a) -76(2) H(4) -C(4) -C(8a) "-H(8a)" 42(2) H(4) -C(4) -C(8a) "-C(1)" 161(2) C(1 ) • -C(8a) -C(8a) "-H(8a)" -177.8(13) Table V (continued) C U P -C(8a) -C(8a)" -H(8a)" 56.0(1 3) H(8a) "-C(8a) -C(8a)" -C(4) 56.0(1 3) H(8a) n-C(8a) -C(8a)" - H ( 8 a ) n -63(3) H(8a) n-C(8a) -C(8a)" -CO )" -177.8(1 3) H1 (5) -C(1)" - C ( 2 ) " -C(21)" -71(3) HI (5) -CO )" -C(2)" - C ( 3 ) " 110(3) H2(5) -C(1)" -C(2)" -C(21)" 42(4) H2(5) -C(1)" -C(2 ) " -C( 3 ) " -137(4) H1 (5) -C(1)" -C(8a)" -C(4) 44(3) H1 (5) -C(1)" -C(8a)" -C(8a) -80(3) H1 (5) -C(1)" -C(8a)" -H(8a)" 164(3) H2(5) -C(1)" - C ( 8 a ) n -C(4) -65(4) H2(5) -CO )" - C ( 8 a ) n -C(8a) 171(4) H2(5) - C O ) " -C(8a)" -H(8a)" 55(4) CHAPTER II 2,3-DIMETHYL-4a0,5,8,8a 0-TETRAHYDRO-1-NAPHTHOQUIN-4a~OL AND 6,7-DIMETHYL-4a0,5,8,8a0-TETRAHYDRO-1-NAPHTHOQUIN-4a- 43 I n t r o d u c t i o n The s t r u c t u r e s of the t i t l e compounds were i n v e s t i g a t e d and f u r t h e r c o n f i r m a t i o n of the geometric requirements l e a d i n g to the e s t a b l i s h e d naphthoquinol r e a c t i o n p a t t e r n s was sought from the s t r u c t u r a l data. Exper imental P r e p a r a t i o n of the t i t l e compounds i n v o l v e d sodium borohydride r e d u c t i o n of the a p p r o p r i a t e D i e l s - A l d e r adducts r e s u l t i n g from the thermal r e a c t i o n s between butadiene and 2,3- dimethyl-benzoquinone, and between 2,3-dimethylbutadiene and benzoquinone which y i e l d e d the 2,3- (IV) and 6,7- dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4c-ols 1 (V), r e s p e c t i v e l y . C r y s t a l s of the i n d i v i d u a l compounds were a f f o r d e d by slow evaporation of petroleum e t h e r / e t h a n o l s o l u t i o n s and were shown to be b e t t e r than 98 per cent pure by GC a n a l y s i s . Mass s p e c t r a l data confirmed the assigned chemical formulae C 1 2 H l 6 0 2 . A l l c r y s t a l s e x h i b i t e d a c i c u l a r h a b i t s and those chosen f o r data c o l l e c t i o n were cut from l a r g e r c r y s t a l s to measure 0.1 x 0.3 x 0.5mm3 and 0.4 x 0.2 x 0.1mm3 f o r the 2,3- and 6,7-dimethyl compounds, r e s p e c t i v e l y . 1 IUPAC names: 4a-hydroxy-2,3-dimethyl-4ap,5,8,8a*-tetrahydro- 1(4H)-naphthalenone and 4o-hydroxy-6,7-dimethyl-4ap,5,8,8ap- tetrahydro-1(4H)-naphthalenone 44 2,3-Dimethy1-4ag,5,8,8ag-tetrahydro-1-naphthoquin-4o-ol (IV) C r y s t a l d ata: C 1 2 H 1 6 0 2 , MW = 192.3, orthorhombic a = 5.148(1), b = 12.269(2), c = 16.478(3) .A, V = 1040.8(4) A 3, Z = 4, D £ = 1.226 g cm* 3, »«(MoKo) = 0.764 cm' 1, V = 0.71073 A, space group £2,2,2,; h00, h = 2n + 1, 0k0, k = 2n + 1 , 003., 1 = 2n + 1 absent. 6,7-Dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4c-ol (V) C r y s t a l data: C 1 2 H 1 6 0 2 , MW = 192.3, mon o c l i n i c a = 9.242(3), b = 22.724(3), c = 5.139(2) A, p = 102.7(1)°, V = 1052.8(5) A 3, Z = 4, D = 1.213 g cm" 3, *(MoKc) = 0.756 cm" 1, X = 0.71073 A, — c space group P2,/c; hOl, 1 = 2n + 1, OkO, k = 2n + 1 absent. P O 45 F i n a l c e l l c onstants f o r both s t r u c t u r e s were obtained by l e a s t squares f i t to the sin6 values f o r 25 centered r e f l e c t i o n s . In the remaining 'Experimental' t e x t , q u a n t i t i e s i n brackets r e f e r to the 6,7-dimethyl compound. Parameters a f t e r which no brackets f o l l o w are to be regarded as the same for both t i t l e compounds. Data c o l l e c t i o n proceeded i n the t h e t a range 0.0-27.5° [0.0-25.0°] using g r a p h i t e monochromatized MoKo r a d i a t i o n . An o -2(4/6)6 [ u-26] scan was employed with an o-scan angle of (0.75 + 0.35tan6) [(0.55 + 0.35tan6)] degrees. Each scan was extended 25% on both s i d e s of the peak to allow f o r background measurement. The h o r i z o n t a l s l i t width was v a r i e d a c c o r d i n g to the 6-dependent r e l a t i o n s h i p (2.00 + I.OOtanO) mm [(2.50 + 1.00tan6) mm] while the v e r t i c a l s l i t remained open at a constant 4 mm. The s e t t i n g angles of three r e f e r e n c e r e f l e c t i o n s were checked p e r i o d i c a l l y to ensure proper c r y s t a l o r i e n t a t i o n throughout data c o l l e c t i o n . Three other r e f l e c t i o n s were chosen as i n t e n s i t y c o n t r o l s and monitored every 3600 s of X-ray exposure time. P r o c e s s i n g of the data which i n c l u d e d a p p l i c a t i o n of Lorentz and p o l a r i z a t i o n - c o r r e c t i o n s , showed l i t t l e or no decay i n the check r e f l e c t i o n s ' i n t e n s i t i e s . Of the 1413 [1834] r e f l e c t i o n s c o l l e c t e d , 671 [626], or 47.5% [34.1% (55% f o r 0°<6<20°)] were c l a s s i f i e d as observed having I "> 3«r(I), where « 2 ( I ) i s d e f i n e d as S + 2B + (0.04(S - B) ) 2 ; S i s the scan count and B the time-averaged background. The l i n e a r a b s o r p t i o n c o e f f i c i e n t s i n d i c a t e d that a b s o r p t i o n c o r r e c t i o n s 46 were not warranted. S o l u t i o n and Refinement 2,3-Dimethyl-4ai,5,8,8ag-tetrahydro-1-naphthoquin-4o-ol The s t r u c t u r e was s o l v e d by d i r e c t methods using the l a r g e s t 156 E-values. The a c e n t r i c E - d i s t r i b u t i o n was c o n s i s t e n t with the p r e v i o u s l y a s s i g n e d non-centrosymmetric space group. The E-map obtained from the s o l u t i o n with the h i g h e s t f i g u r e of merit in MULTAN c l e a r l y i n d i c a t e d the p o s i t i o n s of the 14 non- hydrogen atoms. A f t e r two c y c l e s of f u l l matrix l e a s t squares refinement of non-hydrogen atoms with a n i s o t r o p i c thermal parameters, a d i f f e r e n c e - F o u r i e r map re v e a l e d the p o s i t i o n s of the 16 hydrogens. Convergence was reached at R = 0.031 and Rw = 0.036 f o r the observed data (I > 3c(D), whereas, for the complete data set R = 0.103 and Rw = 0.036. The weighting scheme w = 1/* 2(F) was employed 2, where « 2 ( F ) i s d e r i v e d from the p r e v i o u s l y d e f i n e d * 2 ( I ) . A weighting a n a l y s i s confirmed the s u i t a b i l i t y of the chosen weights by showing uniform average v a l u e s of w(|Fo| - k | F c | ) 2 over ranges of |Fo|. A d i f f e r e n c e s y n t h e s i s , f o l l o w i n g refinement, showed random f l u c t u a t i o n s with the highest peak corresponding to 0.15 e/A 3. In the f i n a l c y c l e of refinement 191 parameters were v a r i e d using 671 observed data and no parameter s h i f t exceeded 0.39*. The standard d e v i a t i o n i n an o b s e r v a t i o n of u n i t weight was 1.210. 2 The F i n * 2 ( F ) and a l l subsequent occurrences of F, not foll o w e d by the m o d i f i e r s 'o' or 'c', are synonymous with Fo. 47 6,7-Dimethyl-4a0,5,8,8ai-tetrahydro-1-naphthoquin-4o-ol MULTAN y i e l d e d the p o s i t i o n a l parameters f o r the 14 non- hydrogen atoms. F o l l o w i n g f u l l matrix l e a s t squares refinement of the non-hydrogen atoms, the c o o r d i n a t e s of the 16 hydrogen atoms were obtained from a d i f f e r e n c e - F o u r i e r map. Refinement proceeded with a n i s o t r o p i c thermal parameters f o r carbons and oxygens and i s o t r o p i c thermal parameters f o r the hydrogens u n t i l the refinement converged. The d i f f e r e n c e - F o u r i e r , c a l c u l a t e d a f t e r convergence, i n d i c a t e d t h a t the l a r g e s t peak, cor responding to excess d e n s i t y of 0.12 e/A 3, was i n the immediate v i c i n i t y of 0 ( 1 ) . The mean and maximum parameter s h i f t s on the f i n a l c y c l e of refinement were 0.020 and 0.20*, r e s p e c t i v e l y . The weights used i n the refinement, w = 1/* 2(F) gave uniform average v a l u e s of w(|Foj - k j F c | ) 2 over ranges of |Fo|. The f i n a l R-value was 0.032 and Rw = 0.037 for the 191 parameters and 626 o b s e r v a t i o n s , whereas f o r the complete data set R = 0.167 and Rw = 0.037. The standard d e v i a t i o n i n an o b s e r v a t i o n of u n i t weight was 1.193. F i n a l atomic c o o r d i n a t e s and temperature f a c t o r s f o r (IV) and (V) are given i n Table VI. A n i s o t r o p i c thermal parameters f o r non-hydrogen atoms are presented i n Table V I I . D i s c u s s i o n Molecules of (IV) and (V) assume a conformation which i s s i m i l a r to that found i n other t e t r a h y d r o n a p h t h o q u i n o l s (Chapter I and r e f e r e n c e 32). The t o r s i o n a n g l es, C(5)-C(4a)-C(8a)-C(1), of 66.6(3)° f o r (IV) and 67.3(4)° f o r (V) (Table V I I I ) , i n d i c a t e the degree of t w i s t i n t h i s conformation, which c o n s i s t s of a 48 Table VI F i n a l p o s i t i o n a l ( f r a c t i o n a l x 1 0 " , H x 1 0 3 ) and i s o t r o p i c thermal parameters (U x 1 0 3 A 2) with estimated standard d e v i a t i o n s in parentheses 2,3-dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4a-ol Atom X 1 z Ueq/Ui so C(1 ) 3659( 8) 31 ( 3) 1 937( 2) 41 C(2) 361 2 ( 7) -1 61 < 3) 1 055 ( 2) 41 C(21 ) 1 863 ( 1 1 ) -1062 < 4) 770( 4) 63 C(3) 5099( 7) 441 ( 3) 550( 2) 40 C(31 ) 5222 ( 12) 238 ( 5) -351 ( 3) 67 C(4) 6849( 7) 1 340 ( 3) 862< 2) 38 C(4a) 6 1 56 ( 7) 1 739( 3) 1 706 ( 2) 34 C(5) 3753( 9) 2472( 3) 1 728 ( 2) 40 C(6) 2729( 7) 2621 < 3) 2571 < 2) - 44 C(7) 3430 ( 9) 2024< 3) 3 1 93 < 2) 49 C(8) 5332( 10) 1 1 1 3< 4) 3 1 42 < 2) 52 C(8a) 5790( 7) 754< 3) 2268 2) 39 0(1 ) 2076( 5) -400< 2) 23861 2) 59 0(4) 70 1 7 ( 6) 2225 2) 292 2) 47 . . H1(21 ) 279(1 4) -1 66 ( 5) 65( 3) 1 30(25) H2(21 ) 45(1 8) -1 29 { 7) 1 08 ( 5) 205(41) H3(21 ) 102(1 6) -93( 6) 21 ( 4) 165(29) H1(31 ) 499(1 1 ) -46( 4) -48( 3) 103(20) H2(31 ) 432( 1 1 ) 77( 4) -67( 3) 106(22) H3(31 ) 712(1 4) 43( 5) -54( 4) 139(24) H(4) 866( 7) 1 03 ( 2) 86( 2) 30( 8) H(4a) 765( 7) 2 1 8 ( 3) 1 90 ( 2) 40(10) H1 (5) 229( 8) 21 2( 3) 1 35( 2) 67(12) H2(5) 422( 7) 31BC" 3) 1 50 ( 2) 38(10) H(6) 1 55 ( 8) .323 ( 3) 262 ( 2) 47(10) H(7) 287( 8) 2 1 6 ( 3) 377 ( 2) 58(11) H1 (8) 479( 9) 46( 4) 346( 3) 78(15) H2(8) 694( 9) 1 29( 3) 340( 2) 68(13) H(8a) 727( 7) 39( 2) 221 ( 2) 24( 9) H(04) 570(1 2) 245( 5) 1 9 ( 3) 98(22) Table VI (continued) 6,7-dimethyl-4a*,5,8,8ap-tetrahydro-1-naphthoquin-4a-ol Atom x z Ueq/Uiso C(1 ) -877( 4) -560( 2) 1056( 9) 40 C(2) 502( 5) -805( 2) 2635(10) 43 C(3) 1 047 ( 5) -1307( 2) 1972( 9) 43 C(4) 357 ( 4) -1651( 2) . -443( 9) 41 C(4a) -1 283( 4) - 1 5 1 3 ( 2) - 1388( 9) 36 C(5) -2240( 5) -1 767 ( 2) 396(11 ) 42 C(6) -3800( 5) - 1 5 1 5 ( 2) -116( 9) 46 C(61 ) -4832( 8) -1 847( 3) 1252(18) 72 C(7) -4182( 4) -1036( 2) -1589( 9) 49 C(71 ) -5736( 7) -785( 4) -2182(21) 84 C(8) -3103( 5) -689( 2) -2774(11) 50 C(8a) -1501 ( 4) -848( 2) - 1613( 9) 37 0(1 ) -1460( 3) -1 36 ( 1 ) 1858( 6) 58 0(4) 627( 3) -2265( 1 ) 149( 8) 53 H(2) 94( 4) -58( 2) 423( 9) 60(14) H(3) 1 96 ( 4) -1 46 ( 1 ) 281( 7) 31(10) H(4) 91 ( 4) -1 54 ( 1 ) -191( 7) 42(11) H(4a) -1 59 ( 3) -1 67 ( 1 ) -318( 8) 31(10) HI (5) -1 78 ( 4) -1 70 ( 1 ) 240( 9) 49(13) H2(5) -233( 4) -221 ( 2) 18( 7) 48(12) H1(61 ) -583( 8) - 1 70 ( 3) 75(13) 139(26) H2(61 ) -462( 6) -224( 3) 120(12) 119(25) H3(61) -467( 8) -181 ( 3) 304(17) 163(40) H1 (71 ) -593( 7) -65( 3) -398(15) 126(31) H2(71 ) -579( 8) -43( 3) -152(16) 158(34) H3(71 ) -650( 7) -1 05 ( 3) -191(13) 143(28) H1 (8) -333( 4) -76( 2) -474(10) 64(14) H2(8) -320( 4) -26( 2) -255( 8) 6 0 ( 1 3 ) H(8a) -87( 4) -69( 1 ) -261( 7) 31(11) H(04) -941 ( 5) -243( 2) -121(10) 57(18) 50 Table VII F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10 3 A 2) and t h e i r estimated standard d e v i a t i o n s 2,3-dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4c-ol Atom y 1 y 2 2 y 3 3 y 2 y 3 y 2 3 C( 1 ) 30( 2) 33( 2) 58 ( 3) 6( 2) 4( 2) 10( 2) C(2) 35( 2) 38( 2) 49( 2) 2( 2) 0( 2) 1 ( 2) C(21 ) 55( 3) 48( 3) 86( 4) -1 1 ( 3) -2( 3) -7( 3) C(3) 33( 2) 40( 2) 46( 2) 5( 2) 4( 2) -5( 2) C(31 ) 81 ( 4) 64( 3) 54( 3) -6( 3) 10( 3) -1 5( 3) C(4) 27( 2) 42( 2) 45( 2) 1 ( 2) 1 ( 2) 7( 2) C(5) 36( 2) 38( 2) 46( 2) 4( 2) -3( 2) 6( 2) C(6) 41 ( 2) 42( 2) 50( 3) 2( 2) 4 ( 2) -8( 2) C(7) 49( 3) 57( 2) 39( 2) -2( 2) 2( 2) -2( 2) C(8) 50( 3) 64( 3) 41 ( 3) -2( 3) -7( 2) 12( 2) C(8a) 25( 2) 48( 2) 46( 2) 9( 2) -2( 2) 9( 2) C(4a) 23( 2) 40( 2) 40( 2) -4( 2) -2( 2) 6( 2) 0(1 ) 52( 2) 58 ( 2) 67( 2) -17( 2) 1 5( 2) 8( 1 ) 0(4) 38( 2) 57( 2) 47( 2) -5( 1 ) 6( 1 ) 1 5( 1 ) 6,7-dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4o-ol Atom y i 1 y 2 2 y 3 3 y 2 y 1 3 y 2 3 CO ) 44( 3) 35( 2) 41 ( 3) -3( 2) 13( 2) -1 ( 2) C(2) 47( 3) 42( 3) 39( 3) -6( 2) 6( 2) -7 ( 2) C(3) 34( 3) 52( 3) 44( 3) -1 ( 2) 7( 2) 1 ( 2) C(4) 52( 3) 34( 3) 40( 3) 3( 2) 1 9( 3) 0( 2) C(4a) 46( 3) 39( 2) 25( 3) -2( 2) 10( 2) -3( 2) C(5) 46( 3) 44( 3) 38( 3) -7( 2) 9( 2) 3( 2) C(6) 44( 3) 52( 3) 42( 3) -9( 2) 1 1 ( 2) -10( 2) C(61 ) 62( 4) 77( 5) 87( 6) -6( 3) 38( 4) -1 ( 4) C(7) 39( 3) 57( 3) 46( 3) 4( 2) -1 ( 2) -5( 2) C(71) 49( 4) 85( 5) 1 10( 7) 8( 4) 2( 4) -3( 5) C(8) " 56( 3) 49( 3) 40( 3) 4( 2) 1 ( 2) 5( 2) C(8a) ' 42( 3) 39( 3) 33( 3) -3( 2) 12( 2) 3( 2) 0(1 ) 61 ( 2) 50( 2) 60( 2) 4( 2) 1 1 ( 2) -13( 2) 0(4) 75( 2) 40( 2) 45( 2) 9( 2) 18( 2) -1 ( 2) 51 Table VIII T o r s i o n angles (deg) with estimated standard d e v i a t i o n s i n parentheses 2,3-dimethyl-4a£,5,8,8ap-tetrahydro-1-naphthoquin-4o-ol Atoms Value c( 8a) -c( 1) -C( 2) -C(21) 167.2( 4) c( 8a) -c( 1) -c( 2) -C(3) -12.0( 5) 0( 1 ) -c( 1) -c( 2) -C(21) -11.01 5) 0( 1 ) -c( 1) -c( 2) -C(3) 169.81 3) C( 2) -c( 1) -C( 8a) -C(8) 166.91 3) C( 2) -c( 1) -C( 8a) -C(4a) 42.0( 4) 0( 1 ) -c( 1) -c< 8a) -C(8) -15.01 5) 0( 1 ) -C( 1) -C( 8a) -C(4a) -139.81 3) C( 1 ) -C( 2) -c< 3) -C(31) 176.81 4) C( 1 ) -C( 2) -C( 3) -C(4) 0.51 5) C( 21 ) -c( 2) -C( 3) -C(31) -2.4( 6) C( 21 ) -C( 2) -C( 3) -C(4) -179.71 4) C( 2) -C( 3) -c< 4) -C(4a) -18.81 5) C( 2) -C( 3) -CI 4) -0(4) -146.21 3) C( 31 ) -C( 3) -c< 4) -C(4a) 1 63.8 4) c< 31 ) -C( 3) -c 4) -0(4) 36.4 5) c< 3) -C( 4) -c 4a) -C(5) -75.6 4) CI 3) -c< 4) -c 4a) -C(8a) 48.2 4) 0 4 ) -c< 4) -c 4a) -C(5) 51 .6 I4) 0 4) -c 4) -c [4a) -C(8a) 175.4 (3) c 4a) -c 5) -c '6) -C(7) -13.7 (5) c .6) -c 5) -c [4a) -C(4) 165.6 (3) c '6) -c 5) -c [4a) -C(8a) 42.6 [4) c [5) -c 6) -c [7) -C(8) 0.3 (6) c .6) -c 7) -c [8) -C(8a) -15.7 (6) c i7) -c '8) -c [8a) -C(1 ) -78.9 (5) c (7) -c ,8) -c [8a) -C(4a) 45.0 (5) c ( 1 ) -c 8a) -c [4a) -C(4) -59.0 (4) c [ 1 ) -c [8a) -c [4a) -C(5) 66.6 (4) c (8) -c [8a) -c (4a) -C(4) 174.8 (3) c (8) -c [8a) -c (4a) -C(5) -59.5 (4) c (2) -c [1) -c (8a) -H(8a) -69(2 0 ( 1 ) -c [1 ) -c (8a) -H(8a) 110(2 c (1 ) -c [2) -c (21 ) -H1(21) -102(4 c i 1) -c [2) -c (21 ) -H2(21) 23(6 c i 1) -c [2) -c (21 ) -H3(21) 147(5 c (3) -c (2) -c (21 ) -H1(21) 77(4 c (3) -c [2) -c (21 ) -H2(21) -157(6 c (3) -c (2) -c (21 ) -H3(21) -34(5 52 Table VIII (continued) 2,3-dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4a-ol C(2) -C( 3) -c( 31 ) -H1(31) -31 ( 4) C(2) -c( 3) -C( 31 ) -H2(31) 1 06( 4) C(2) -c( 3) -c( 31) -H3(31) -1 47 ( 3) C(4) -c( 3) -c( 31 ) -H1(31) 1 47( 4) C(4) -c( 3) -c( 31 ) -H2(31) -76( 4) C(4) -c( 3 ) -C( 31 ) -H3(31) 31 ( 4) C(2) -c( ' ) ~* J -c( 4) -H(4) 1 02( 2) C(31 ) -c( 3) -c( 4) -H(4) -751 2) C(3) -c( 4 ) -C( 4a) -H(4a) 1 671 2) 0(4) -c( 4 ) -C( 4a) -H(4a) -661 2) H(4) -c( 4) -C( 4a) -C(5) 1 661 2) H(4) -c( 4 ) -CI 4a) -C(8a) -701 2) H(4) -c( 4 ) -CI 4a) -H(4a) 481 3) C(3) -c( 4 ) -0< 4) -H(04) 571 5) C(4a) -c( 4 ) -0( 4) -H(04) -721 5) H(4) -C( 4 ) -o< 4) -H(04) 1 70I 5) C(4a) -c( 5) -CI 6) -H(6) 1 64I 2) H1 (5) -C( 5) -c< 6) -C(7) 1071 2) H1 (5) -c( 5) -CI 6) -H(6) -75 3) H2(5) -C( 5) -c 6) -C(7) -1 34 2) H2(5) -C( 5) -c 6) -H(6) 43 3) C(6) -C( 5) -c 4a) -H(4a) -77 2) H1 (5) -c< 5) -c 4a) -C(4) 44 ,2) H1 (5) -c< 5) -c 4a) -C(8a) -79 2) H1 (5) -CI 5) -c 4a) -H(4a) 161 '3) H2(5) -CI 5) -c .4a) -C(4) -73 (2) H2(5) -c< 5) -c ,4a) -C(8a) 1 63 (2) H2(5) -c 5) -c ,4a) -H(4a) 44 (3) C(5) -c 6) -c '7) -H(7) 174 (3) H(6) -c 6) -c (7) -C(8) -1 77 (2) H(6) -c 6) -c (7) -H(7) -3 (4) C(6) -c 7) -c (8) -HI(8) -1 38 (3) C(6) -c 7 ) -c (8) -H2(8) 1 09 (3) H(7) -c 7 ) -c (8) -C(8a) 169 (2) H(7) -c 7) -c (8) -H1(8) 47 (4) H(7) -c 7) -c (8) -H2(8) -66 (4) C(7) -c [8) -c (8a) -H(8a) 1 60 (2) HI (8) -c 8) -c (8a) -C( 1 ) 46 (3) H1 (8) -c (8) -c (8a) -C(4a) 1 70 (3) HI (8) -c r8) -c (8a) -H(8a) -75 (3) H2(8) -c 8) -c (8a) -C( 1 ) 1 56 (3) H2(8) -c 6) -c (8a) -C(4a) -80 (3) H2(8) -c [8) -c (8a) -H(8a) 35 (3) C(1 ) -c (8a) -c (4a) -H(4a) -175 (2) C(8) -c (8a) -c (4a) -H(4a) 59 (2) H(8a) -c (8a) -c (4a) -C(4) 54 (2) H(8a) -c (8a) -c (4a) -C(5) 180 (2) H(8a) -c (8a) -c (4a) -H(4a) -62 (3) Table VIII (continued) T o r s i o n angles (deg) with estimated standard d e v i a t i o n s i n parentheses 6,7-dimethyl-4ap,5,8,8a£-tetrahydro-1-naphthoquin-4o~ol Atoms Value c( 8a) -c( 1) -C(2) -c( 3) -10.4( 6) o( 1 ) -c'( 1) -C(2) -c( 3) 171 ,2( 4) c( 2) -c( 1) -C(8a) -c( 4a) 38.5( 5) C( 2) -c( 1) -C(8a) -c( 8) 164.2( 4) 0( 1 ) -c( 1) -C(8a) -c( 4a) -143.2( 4) 0( 1 ) -c( 1) -C(8a) -c( 8) -17.4( 6) C( 1 ) -c( 2) -C(3) -c( 4) 2.3( 6) c( 2) -c( 3) -C(4) -c( 4a) -23.1( 6) c( 2) -c( 3) -C(4) -o( 4) -147.6( 4) C( 3) -c( 4) -C(4a) -C( 5) -72.7( 5) c< 3) -C( 4) -C(4a) -C( 8a) 50.4( 5) 0( 4) -c< 4) -C(4a) -c( 5) .49.31 5) 0( 4) -C( 4) -C(4a) -c< 8a) 172.4< 4) C( 4) -C( 4a) -C(5) -C( 6) 166.01 4) c< 8a) -C( 4a) -C(5) -C( 6) 43.01 5) c< 4) -C( 4a) -C(8a) -c< 1 ) -58.0 5) C( 4) -c< 4a) -C(8a) -CI 8) 175.1 ,4) C( 5) -C( 4a) -C(8a) -c< 1 ) 67.3 5) c< 5) -c< 4a) -C(8a) -c 8) -59.5 (5) c 4a) -c< 5) -C(6) -c 61 ) 168.6 (5) c 4a) -c 5) -C(6) -c ,7) -12.9 (6) c 5) -c 6) -C(7) -c (71 ) 178.5 (6) c ,5) -c 6) -C(7) -c (8) -2.7 (7) c ,61 ) -c '6) -C(7) -c (71 ) -3.1 (9) c (61 ) -c (6) -C(7) -c (8) 175.6 (6) c 6) -c (7) -C(8) -c (8a) -13.6 (7) c (71 ) -c (7) -C(8) -c (8a) 165.3 (5) c (7) -c (8) -C(8a) -c (1) -80.2 (5) c (7) -c (8) -C(8a) -c (4a) 44.7 (6) c (8a) -c (1 ) -C(2) -H (2) 173(3 0 (1 ) -c (1 ) -C(2) -H (2) -6(3 c (2) -c (1) -C(8a) -H (8a) -77(2 0 (1 ) -c (1) -C(8a) -H (8a) 102(2 c (1 ) -c (2) -C(3) -H (3) 174(3 H (2) -c (2) -C(3) -c (4) 179(3 H (2) -c (2) -C(3) -H (3) -10(4 c (2) -c (3) -C(4) -H (4) 97(2 H (3) -c (3) -C(4) -c (4a) 164(2 H (3) -c (3) -C(4) -o (4) 40(2 54 Table VIII (continued) 6,7-dimethyl-4a0,5,8,8ap-tetrahydro-1-naphthoquin-4o-ol H(3) -c( 3) -c( 4) -H(4) -75(3 C(3) -c( 4) -c( 4a) -H(4a) 165(2 0(4) -c( 4) -c( 4a) -H(4a) -73(2 H(4) -c( 4) -c( 4a) -C(5) 168(2 H(4) -c( 4) -c( 4a) -C(8a) -69(2 H(4) -c( 4) -c( 4a) -H(4a) 47(3 C(3) -c( 4) -o( 4) -H(04) 112.3 C(4a) -c( 4) -0( 4) -H(04) -11.8 H(4) -C( 4) -o( 4) -H(04) -132(2 C(4) -c( 4a) -CI 5) -HI(5) 45(2 C(4) -c( 4a) -c( 5) -H2(5) -72(2 C(8a) -c< 4a) -CI 5) -H1(5) -78(2 C(8a) -CI 4a) -CI 5) -H2(5) 1 65(2 H(4a) -C( 4a) -CI 5) -C(6) -74(2 H(4a) -c< 4a) -CI 5) -H1(5) 1 65(3 H(4a) -c< 4a) -CI 5) -H2(5) 48(3 C(4) -CI 4a) -CI 8a) -H(8a) 51(2 C(5) -CI 4a) -CI 8a) -H(8a) 176(2 H(4a) -CI 4a) -CI 8a) -C(1 ) -173(2 H(4a) -CI 4a) -CI 8 a ) -C(8) 60(2 H(4a) -CI 4a) -CI 8a) -H(8a) -65(3 H1 (5) -c 5) -c 6) -C(61) -67(2 H1 (5) -c 5) -c 6) -C(7) 112(2 H2(5) -c 5) -c 6) -C(61) 45(2 H2(5) -c ,5) -c 6) -C(7) -136(2 C(5) -c ,6) -c ,61 ) -H1(61) -174(4 C(5) -c [6) -c '61 ) -H2(61) -37(4 C(5) -c [6) -c (61 ) -H3(61) 71(5 C(7) -c (6) -c (61 ) -H1(61) 7(4 C(7) -c (6) -c (61 ) -H2(61) 144(4 C(7) -c (6) -c (61 ) -H3(61) -107(5 C(6) -c (7) -c (71 ) -H1(71) -142(4 C(6) -c (7) -c (71 ) -H2(71) 116(6 C(6) -c (7) -c (71 ) -H3(71) - 1 8 ( 5 C(8) -c (7) -c (71 ) -H1(71 ) 39(4 C(8) -c (7) -c (71 ) -H2(71) -63(6 C(8) . -c (7) -c (71 ) -H3(71) 163(4 C(6) -c (7) -c (8) -H1(8) 108(2 C(6) -c (7) -c (8) -H2(8) -136(2 C(71 ) -c (7) -c (8) -H1(8) -73(2 C(71 ) -c (7) -c (8) -H2(8) 43(2 C(7) -c (8) -c (8a) -H(8a) 168(2 H1 (8) -c (8) -c (8a) -C(1) 159(2 H1 (8) -c (8) -c ( 8 a ) -C(4a) -76(3 H1 (8) -c (8) -c (8a) -H(8a) 47(3 H2(8) -c (8) -c (8a) -C(1 ) 45(3 H2(8) -c (8) -c (8a) -C(4a) 169(3 H2(8) -c (8) -c (8a) -H(8a) -68(4 55 h a l f - c h a i r cyclohexene r i n g c i s - f u s e d to a second h a l f - c h a i r cyclohexenone moiety ( F i g . 10). The hydroxyl group i n both s t r u c t u r e s occupies the l e s s s t e r e o c h e m i c a l l y hindered pseudo- e q u a t o r i a l p o s i t i o n in the cyclohexenone r i n g . R e l a t i v e l y short d i s t a n c e s between the p-enone carbon C(3), and H1(5) f and between the c-enone carbon C(2), and C(5) are a r e s u l t of t h i s conformation. Such molecular geometry makes H 1 ( 5 ) - a b s t r a c t i o n by C(3) and subsequent c o l l a p s e of the ensuing b i r a d i c a l , (C(2)...C(5) ) , h i g h l y f a v o r a b l e upon u l t r a v i o l e t i r r a d i a t i o n . T h i s sequence i s observed f o r both the 2,3- and 6,7-dimethyl compounds i n which the C(3) to H1(5) d i s t a n c e s are 2.84(4) and 2.82(3) A, r e s p e c t i v e l y . Both these v a l u e s are l e s s than the suggested (26) van der Waals r a d i i sum l i m i t of 2.90 A f o r hydrogen a b s t r a c t i o n by carbon. A l i s t of other parameters i n v o l v e d i n the a b s t r a c t i o n r e a c t i o n i s given i n Table IX. A f u r t h e r consequence of t h i s t w i s t e d conformation in the s o l i d s t a t e , e x h i b i t e d by naphthoquinols i n which the hydroxyl group i s ant i to the bridgehead s u b s t i t u e n t s , i s the g e o m e t r i c a l l y s u i t a b l e p o s i t i o n of the p-hydrogen, H(8), to oxygen a b s t r a c t i o n . Although t h i s r e a c t i o n i s observed i n s u b s t i t u t e d naphthoquinones (26), i t s absence in the p h o t o r e a c t i v i t y of naphthoquinols has been r a t i o n a l i z e d on the b a s i s of the f o l l o w i n g two p o i n t s (29). F i r s t l y , in the quinone systems, the carbonyl group a i d s i n s t a b i l i z i n g the b i r a d i c a l r e s u l t i n g from i n t r a m o l e c u l a r p-H a b s t r a c t i o n , whereas, the q u i n o l s l a c k t h i s p o s s i b i l i t y of n - e l e c t r o n d e r e a l i z a t i o n . Secondly, any charge t r a n s f e r i n t e r a c t i o n (which may be r e q u i r e d f o r p-H a b s t r a c t i o n ) between the cyclohexene double bond and the 56 F i g u r e 10 Stereo diagrams of 2,3-dimethyl-4ap,5,8,8ap-tetrahydro-1 - naphthoquin-4a-ol ( t o p ) , and 6,7-dimethyl- 4ap,5,8,8ap-tetrahydro-1-naphthoquin-4c-ol (bottom). 57 e x c i t e d ene-one chromophore i s f a c i l i t a t e d by the 2-ene-1,4- dione moiety which i s a b e t t e r e l e c t r o n acceptor than the 2-ene- 1-one chromophore. While the 2,3-dimethyl-naphthoquinol (IV) e x h i b i t s no oxygen a b s t r a c t i o n p h o t o r e a c t i v i t y , the 6,7-dimethyl compound y i e l d s a second s o l i d s t a t e photoproduct which r e s u l t s from the unprecedented tetrahydronaphthoquinol r e a c t i o n , oxygen Table IX Geometrical parameters in the p-enone a b s t r a c t i o n r e a c t i o n T c = angle between C(3)...H1(5) v e c t o r and the plane of the C(2)=C(3) double bond A = H1(5)..,C(3)=C(2) angle. A„(°) T (°) C(3)...H1(5) (A) C(2)...C(5) (A) c c (IV) 79.7(8) 54.1 2.84(4) 3.416(5) (V) 80.9(7) 56.7 2.82(3) 3.353(6) a b s t r a c t i o n of a p-hydrogen. The p e r t i n e n t g e o m e t r i c a l f a c t o r s in the a b s t r a c t i o n process are T 0 , the angle subtended by the oxygen to p-H v e c t o r and i t s p r o j e c t i o n onto the plane of the c a r b o n y l group, and- A Q, the C(1)=0(1 ) . . . p-H angle. These angles are 1 and 81(1) degrees, r e s p e c t i v e l y which are c l o s e to the i d e a l a b s t r a c t i o n angles of T 0 = 0° and A 0 = 90°. F u r t h e r i n v e s t i g a t i o n of the u n s u b s t i t u t e d and other s u b s t i t u t e d t e t r a h y d r o n a p h t h o q u i n o l s r e v e a l s that the oxygen 58 a b s t r a c t i o n photoprocess occurs only in the systems in which the 2 and 3 p o s i t i o n s on the cyclohexenone moiety are u n s u b s t i t u t e d (35). T h i s suggests that once c o n f o r m a t i o n a l c o n t r o l i s e s t a b l i s h e d , methyl s u b s t i t u t i o n (or lack t h e r e o f ) on the enone double bond p l a y s a c r i t i c a l r o l e i n determining the photochemical r e a c t i o n pathway in the s o l i d s t a t e . In view of these recent f i n d i n g s , the p r e v i o u s r a t i o n a l e (page 55) used i n e x p l a i n i n g the l a c k of oxygen a b s t r a c t i o n i n t e t r a h y d r o n a p h t h o g u i n o l s becomes l e s s g e n e r a l . I r r a d i a t i o n in s o l u t i o n , where c o n f o r m a t i o n a l e q u i l i b r a t i o n i s f a c i l e a f f o r d s mainly i n t r a m o l e c u l a r [2+2] c y c l o a d d u c t s (35) owing to the presence of higher energy conformers which plac e the two i n t r a m o l e c u l a r double bonds p a r a l l e l to each other and w i t h i n r e a c t i n g d i s t a n c e . The absence of [2+2] i n t r a m o l e c u l a r c y c l o a d d i t i o n products i n the s o l i d s t a t e p h o t o l y s i s of (IV) and (V) i s due mainly to the i n a b i l i t y of the r e a c t a n t molecules to undergo the e x t e n s i v e c o n f o r m a t i o n a l rearrangement r e q u i r e d to a t t a i n the r e a c t i n g geometry. In the ground s t a t e , the C=C double bonds are n o n - p a r a l l e l with C(2)...C(7) and C(3)...C(6) s e p a r a t i o n s of 4.427(5) and 4.442(5) A, r e s p e c t i v e l y f o r ( I V ) , and 4.427(6) and 4.397(6) A f o r (V). G e n e r a l l y , bond l e n g t h s and angles (Table X) correspond to accepted v a l u e s (33). However, angles i n v o l v i n g the methyl groups d e v i a t e s l i g h t l y from the normal v a l u e s , r e f l e c t i n g the s t e r i c i n t e r a c t i o n between adjacent s u b s t i t u e n t s . Molecules of (IV) are l i n k e d i n the c r y s t a l ( F i g . 11) by 0(4)-H...0(4) hydrogen bonds 'to form chains running along a. The 0(4)-H...0(4) angle i s 166(6)° with an H...0(4) d i s t a n c e of 59 F i g u r e 1 1 Stereo packing diagram of 2,3-dimethyl-4ap,5,8,8ap-tetrahydro-1 - naphthoquin-4o-ol ( t o p ) , and 6,7-dimethyl- 4ap,5,8,Bap-tetrahydro-1-naphthoquin-4c-ol (bottom). 60 2.09(6) A; the 0(4)...0(4) s e p a r a t i o n i s 2.830(2) A. S i m i l a r l y , 0(4)-H...0(4) i n t e r a c t i o n s j o i n molecules of (V) i n the c r y s t a l forming a l i n k a g e along the c - a x i s . The hydrogen bond angle and d i s t a n c e are 171(5)° and 2.00(5) A, r e s p e c t i v e l y , and the 0(4)...0(4) d i s t a n c e i s 2.783(2) A. A l l other i n t e r m o l e c u l a r c o n t a c t s correspond to normal van der Waals d i s t a n c e s . 61 Table X 2,3-dimethyl-4a0,5,8,8a£-tetrahydro-1-naphthoquin-4c-ol Bond lengths (A) with estimated standard d e v i a t i o n s in parentheses Bond Length Bond Length C O ) -C(2) 1.471(5) C(4) -0(4) 1.438(4) C O ) -C(8a) 1.512(5) C(5) -C(6) 1.497(5) C O ) -0(1) 1.221(4) C(5) -C(4a) 1.530(5) C(2) -C(21) 1.502(6) C(6) -C(7) 1.310(5) C(2) -C(3) 1.351(5) C(7) -C(8) 1.489(6) C(3) -C(3 1 ) 1.506(7) C(B) -C(8a) 1.525(6) C(3) ~C(4) 1.514(5) C(8a) -C(4a) 1.533(5) C(4) -C(4a) 1.518(5) Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -CO ) -C(8a) 1 17 .5(3) C(4a) -C(4) -0(4) 111. 7(3) C(2) -CO ) -0(1) 121 .2(4) C(6) -C(5) -C(4a) 1 12. 2(3) C(8a) -CO ) -0(1) 121 .3(3) C(5) -C(6) -C(7) 124. 1(3) C O ) -C(2) -C(21) 1 15 .9(4) C(6) -C(7) -C(8) 123. 9(4) C O ) -C(2) -C(3) 120 .8(3) C(7) -C(8) -C(8a) 111. 8(4) C(21 ) -C(2) -C(3) 123 .3(4) C O ) -C(8a) -C(8) 113. 4(3) C(2) -C(3) -C(31) 122 .7(4) C O ) ~-C% 8a) -C(4a) 109. 5(3) C(2) -C(3) -C(4) 121 .8(3) C(8). -C(8a) -C(4a) 111. 2(3) C(31 ) -C(3) -C(4) 1 15 .5(4) C(4) -C(4a) -C(5) 113. 6(3) C(3) -C(4) -C(4a) 1 1 3 .9(3) C(4) -C(4a) -C(8a) 109. 2(3) C(3) -C(4) -0(4) 1 1 1 .3(3) C(5) -C(4a) -C(8a) 110. 5(3) 62 Table X (continued) 2 , 3-dimethyl-4a0,5,8,8ap-tetrahydro-1-naphthoquin-4a-ol Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(21 ) -H1(21 ) 0.90(6) C(5) -H2(5) 0. 98(3) C(21 ) -H2(21 ) 0.93(9) C(6) -H(6) 0. 96(4) C(21 ) -H3(21 ) 1.04(8) C(7) -H(7) 1 . 00(3) con- -H1 (31 ) 0.89(5) C(8) -H1(8) 0. 99(4) con -H2(31 ) 0.96(5) C(8) -H2(8) 0. 96(5) con -H3(31 ) 1.05(7) C(8a) -H(8a) 0. 89(3) C(4) -H(4) 1.01(3) C(4a) -H(4a) 0. 99(4) C(5) -H1(5) 1.07(4) 0(4) -H(04) 0. 75(6) Bond angles i n v o l v i n g hydrogen atoms (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -C(21) -H1(21) 110(4) C(4a) -C(5) -H2(5) 108(2) C(2) -C(21) -H2(21) 121(5) H1 (5) -C(5) -H2(5) 108(3) C(2) -C(21) -H3(21) 115(4) C(5) -C(6) -H(6) 114(2) H1(21 ) -C(21 ) -H2(21) 107(5) C(7) -C(6) -H(6) 122(2) H1(21) -C(21 ) -H3(21) 99(5) C(6) -C(7) -H(7) 124(2) H2(21 ) -C(21) -H3(21) 102(6) C(8) -C(7) -H(7) 112(2) C O ) -con -H1(31) 113(4) C(7) -C(8) -H1(8) 113(3) C O ) -con -H2(31) 114(3) C(7) -C(8) -H2(8) 112(3) C O ) C(31 ) -H3(31) 107(3) C(8a) -C(8) -HI(8) 108(3) H1(31 ) -con -H2(31) 117(5) C(8a) -C(8) -H2(8) 111(3) H1(31 ) -con -H3(31) 106(5) H1 (8) -C(8) -H2(8) 101(4) H2(31 ) -con -H3(31) 98(4) C(1) -COa) -H(8a) 106(2) C O ) C(4) -H(4) 106(2) C(8) -C(8a) -H(8a) 113(2) C(4a) -C'(4) -H(4) 110(2) C(4a) -C(8a) -H(8a) 103(2) 0(4) -C(4) -H(4) 104(2) C(4) -C(4a) -H(4a) 106(2) C(6) -C(5) -H1(5) 110(2) C(5) -C(4a) -H(4a) 107(2) C(6) -C(5) -H2(5) 109(2) C(8a) -C(4a) -H(4a) 110(2) C(4a) -C(5) -H1(5) . 108(2) C(4) -0(4) -H(04) 111(5) 63 Table X (continued) 6,7-dimethyl -4ap,5,8,Sap- tetrahydro-1-naphthoquin-4c-ol Bond lengths (A) with, estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C O ) -C(2) C O ) -C(8a) C O ) -0(1) C(2) -C(3) C(3) -C(4) C(4) -C(4a) C(4) -0(4) C(4a) -C(5) 1.463(6) 1.514(6) 1.219(4) 1.321(5) 1 .487(6) 1 .519(5) 1 .437 (5) 1 .521(5) C(4a) -C(8a) C(5)> -C(6) C(6) -C(61) C(6) -C(7) C(7) -C(71) C(7) -C(8) C(8) -C(8a) 1.525(5) 1.520(6) 1.506(7) 1.327(5) 1.514(7) 1 .501(6) 1 .514(5) Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -CO ) -C(8a) 116. 7(4) C(4a) -C(5) -C(6) 114. 1 (4) C(2) -CO) -0(1 ) 120. 6(4) C(5) -C(6) -C(61) 113. 8(5) C(8a) -CO ) -0(1 ) 1 22. 6(4) C(5) -C(6) -C(7) 1 22. 0(4) C O ) -C(2) -C(3) 121. 4(5) C(61 ) -C(6) -C(7) 124. 1(5) C(2) -C(3) -C(4) 123. 5(4) C(6) -C(7) -C(71) 123. 1 (5) C(3) -C(4) -C(4a) 111. 9(4) C(6) -C(7) -C(8) 123. 0(4) C(3) -C(4) -0(4) 1 08. 1 (4) C(71 ) -C(7) -C(8) 113. 9(5) C(4a) -C(4) -0(4) 112. 5(3) C(7) -C(8) -C(8a) 113. 2(4) C(4) -C(4a) -C(5) 113. 6(4) C O ) -C(8a) -C(4a) 110. 0(3) C(4) -C(4a) -C(8a) 109. 6(3) C O ) -C(8a) -C(8) 1 13. 5(4) C(5) -C(4a) -C(8a) 109. 7(4) C(4a) -C(8a) -C(8) 111. 6(4) 64 Table X (continued) 6,7-dimethyl-4a0,5,8,8a£-tetrahydro-1-naphthoquin-4c-ol Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(2) -H(2) 0.98(4) C(61 ) -H3(61) 0.90(8) C(3) -H(3) 0.93(3) C(71 ) -H1(71) 0.95(7) C(4) -H(4) 1 .03(4) C(71 ) -H2(71) 0.88(8) C(4a) -H(4a) 0.97(4) C(71 ) -H3(71) 0.96(6) C(5) -HI(5) 1.04(4) C(8) -H1(8) 1 .00(5) C(5) -H2(5) 1.01(4) C(8) -H2(8) 0.98(4) C(61 ) -H1(61) 0.96(7) C(8a) -H(8a) 0.93(3) C(61 ) -H2(61) 0.91(6) 0(4) -H(04) 0.79(5) Bond angles i n v o l v i n g hydrogen atoms (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(1 ) -C(2) -H(2) 1 15(2) H1(61) -C(61) -H2(61) 122(5) C(3) -C(2) -H(2) 124(2) H1(61) -C(61) -H3(61) 100(6) C(2) -C(3) -H(3) 125(2) H2(61) -C(61) -H3(61) 97(6) C(4) -C(3) -H(3) 111(2) C(7) -C(7 1 ) -H1(71) 106(4) C(3) -C(4) -H(4) 107(2) C(7) -C(71 ) -H2(71) 114(5) C(4a) -C(4) -H(4) 1 10(2) C(7) -C(71 ) -H3(71) 115(4) 0(4) -C(4) -H(4) 107(2) HI (71 ) -C(71 ) -H2(71) 94(6) C(4) -C(4a) -H(4a) 107(2) H1 (71 ) -C(7 1 ) -H3(71) 111(5) C(5) -C(4a) -H(4a) 1 10(2) H2(71 ) -C(71) -H3(71) 114(6) C(8a) -C(4a) -H(4a) 107(2) C(7) -C(8) -HI(8) 108(2) C(4a) -C(5) -HI(5) 112(2) C(7) -C(8) -H2(8) 112(2) C(4a) -C(5) -H2(5) 111(2) C(8a) -C(8) -H1(8) 109(2) C(6) -C(5) -H1(5) 107(2) C(8a) -C(8) -H2(8) 107(2) C(6) -C(5) -H2(5) 107(2) HI (8) -C(8) -H2(8) 106(4) H1 (5) -C(5) -H2(5) 105(3) C(1 ) -C(Ba) -H(8a) 100(2) C(6) -C(61) -H1(61) 112(4) C(4a) -C(8a) -H(8a) 109(2) C(6) -C(61) -H2(61) 108(4) C(8) -C(8a) -H(8a) 112(2) C(6) -C(61) -H3(61) 117(5) C(4) -0(4) -H(04) 108(3) 65 CHAPTER I I I 2 ,3 , 4a,4ap,6 ,"7 /Ba*-HE PTAMETH YX-4af ,5 ,8 ,8a p-TETRAHYDKD- NAPHTHOQUIN-4 p ~OL 66 I n t r o d u c t i o n S o l i d s t a t e / s o l u t i o n p h o t o r e a c t i v i t y d i f f e r e n c e s have been observed i n v a r i o u s s u b s t i t u t e d t e t r a h y d r o n a p h t h o q u i n o l s (29,30,32,35). The divergence i n r e a c t i v i t y p a t t e r n s has been r a t i o n a l i z e d mainly by c o n s i d e r i n g the fundamental d i s t i n c t i o n between the two phases, namely r i g i d i t y i n the l a t t i c e versus m o b i l i t y i n s o l u t i o n . R e actions i n s o l u t i o n , where molecular c o n f o r m a t i o n a l e q u i l i b r a t i o n i s f a c i l e , are governed c h i e f l y by k i n e t i c s , whereas, the s o l i d s t a t e r e a c t i o n s are top o c h e m i c a l l y c o n t r o l l e d . T h i s l a t t i c e c o n t r o l can be e x p l o i t e d by d e s i g n i n g a molecule so that i t s lowest energy conformation ( i n which i t i s most l i k e l y to c r y s t a l l i z e ) i s one which predisposes the molecule to a s p e c i f i c r e a c t i o n . In an e f f o r t to t e s t t h i s c o n f o r m a t i o n a l argument the t i t l e compound 1 was s y n t h e s i z e d . T h i s s t r u c t u r a l study was undertaken to v e r i f y the p r e d i c t e d conformation and to e l u c i d a t e the geometric parameters i n v o l v e d i n the observed photochemical r e a c t i o n . A comparison of t h i s compound and four other tetrahydronaphthoquinol d e r i v a t i v e s ( I I I ) - ( V I I ) i s made i n an attempt to a s c e r t a i n s u b s t i t u e n t e f f e c t s on the v a r i o u s s t r u c t u r e s and t h e i r r e a c t i v i t i e s . Experimental The t i t l e compound was prepared by m e t h y l l i t h i u m treatment 1 IUPAC name: 4p-hydroxy-2,3,4c,4ap,6,7,8ap-heptamethyl- 4ap,5,8,8ap-tetrahydro-1(4H)-naphthalenone 67 of the ene-dione, 2,3,4ap,6,7,8ap-hexamethyl-1,4-naphthoquinone. The two isomers formed were separated by 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 from c y c l o h e x a n e / e t h y l a c e t a t e which y i e l d e d a c i c u l a r c r y s t a l s of ( V I ) . C r y s t a l data: C 1 7 H 2 6 0 2 F MW = 262.4, mo n o c l i n i c a = 7.497(2), b = 16.792(3), c = 12.687(3) A, £ = 105.30(1)°, V = 1540.4(6) A 3, Z = 4, D = 1.141 g cm" 3, D = 1.140 g cm" 3, c o v(MoKa) = 0.675 cm" 1, V = 0.71073 A, space group P2, /c_. On the b a s i s of the absences, h01, 1 = 2n + 1 and OkO, k_ = 2n + 1 from p r e c e s s i o n and Weissenberg photographs, the space group was uniquely determined as P2,/c. Data were c o l l e c t e d with a c r y s t a l of dimensions 0.1 x 0.2 x 0.4 mm3 and g r a p h i t e monochromatized MoKa r a d i a t i o n . In the t h e t a range 0.0- 27.5°, 3516 r e f l e c t i o n s were c o l l e c t e d with an o—© scan type. The omega scan width was c a l c u l a t e d from the e x p r e s s i o n (0.80 + 0.35tan6)° and extended 25% on each s i d e of the peak fo r background measurement. The v e r t i c a l a p e r t u r e was constant at 4 (VI) 68 mm and the h o r i z o n t a l width was v a r i e d with t h e t a a c c o r d i n g to the r e l a t i o n s h i p (2.00 + 1.00tan9) mm. In an attempt to improve the accuracy of the data, a non-equal t e s t , whereby two f i n a l scans are done i n opposite d i r e c t i o n s , was a p p l i e d to each r e f l e c t i o n . The odd and even increments i n the 96 s t e p i n t e n s i t y p r o f i l e were compared on a s t a t i s t i c a l b a s i s and a d i f f e r e n c e between corresponding values i n the two scans of more than one standard d e v i a t i o n was the c r i t e r i o n f o r a repeat of measurement; f a i l u r e a second time caused that r e f l e c t i o n to be tagged making i t r e a d i l y i d e n t i f i a b l e a f t e r data p r o c e s s i n g . P r o c e s s i n g the data, which i n c l u d e d Lorentz and p o l a r i z a t i o n c o r r e c t i o n s a p p l i e d i n the usual manner, i n d i c a t e d that no r e f l e c t i o n f a i l e d the non-equal t e s t t w i c e . Of the 3516 r e f l e c t i o n s c o l l e c t e d , 1934 (55.0%) had I £ 3*(I) where <y2(I) = S + 2B + (0.04(S - B ) ) 2 , S being the scan count and B the time-averaged background. S o l u t i o n and Refinement The p o s i t i o n s of the 19 non-hydrogen atoms were l o c a t e d by MULTAN. Refinement of these atoms with i s o t r o p i c temperature f a c t o r s , f o l l o w e d by two c y c l e s with a n i s o t r o p i c thermal parameters and a subsequent d i f f e r e n c e - F o u r i e r y i e l d e d the c o o r d i n a t e s f o r the 26 hydrogens. Refinement continued u n t i l convergence at R = 0.041 and Rw = 0.056. Towards the end of refinement the weighting scheme was changed from u n i t weights to w = l / t f 2 ( F ) , where * 2 ( F ) i s c a l c u l a t e d from the * 2 ( I ) d e f i n e d above. A weighting a n a l y s i s confirmed the s u i t a b i l i t y of the 69 chosen weights. F o l l o w i n g convergence a f i n a l d i f f e r e n c e s y n t h e s i s was c a l c u l a t e d . The r e s u l t i n g map i n d i c a t e d r e s i d u a l d e n s i t y of 0.2 e/A 3 i n the re g i o n of 0 ( 4 ) . T h i s residue i s p o s s i b l y due to one of the oxygen lone p a i r s . The mean parameter s h i f t on the f i n a l c y c l e of refinement was 0.198*. The maximum s h i f t of 1.290tf corresponded to the o s c i l l a t i n g temperature f a c t o r of the methyl hydrogen, H1(21). The standard d e v i a t i o n i n an o b s e r v a t i o n of u n i t weight was 1.77. F i n a l atomic c o o r d i n a t e s and a n i s o t r o p i c thermal parameters are given i n Tables XI and X I I , r e s p e c t i v e l y . D i s c u s s i o n Molecules of (VI) c r y s t a l l i z e with the conformation common to a l l naphthoquinols s t u d i e d i n t h i s s e r i e s i n which the b u l k i e r s u b s t i t u e n t on C(4) assumes the pse u d o - e q u a t o r i a l p o s i t i o n . Although the 4-OH i s syn to the bridgehead methyl groups, the conformation adopted ( F i g . 12) i s c h a r a c t e r i s t i c of the naphthoquinols which have the hydroxyl group a n t i to the bridgehead s u b s t i t u e n t s , _i.e. a h a l f - c h a i r cyclohexene r i n g c i s - fused to a h a l f - c h a i r cyclohexenone moiety, with the b u l k i e r 4- methyl s u b s t i t u e n t p s e u d o - e q u a t o r i a l . The degree of t w i s t i n the conformation can be d e s c r i b e d by the C(1)-C(8a)-C(4a)-C(5) t o r s i o n angle of 62.2(2)°. The s p a t i a l consequence of t h i s arrangement i s the p r o x i m i t y of the p-enone carbon C(3), to H1(5) (2.81(2) A) (Table X I I I ) . Furthermore, the angle between the C(3)...H1(5) v e c t o r and i t s p r o j e c t i o n onto the plane of the C(3)=C(2) double bond ( C ( 1 ) , . . . , C ( 4 ) ) , T c , and the angle 70 Table XI F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10 5,H x 10 3) and i s o t r o p i c thermal parameters (U x 10 3 A 2 ) with estimated standard d e v i a t i o n s i n parentheses Atom x y_ z Ueq/Uiso C(1 ) 85627(25) 11022(13) 72597(15) 41 C(2) 77531(27) 3371(13) 68018(15) 43 C(21 ) 89061(42) -1482(23) 62201(27) 70 C(3) 60946(28) 1079(12) 68910(16) 42 C(31 ) 52062(46) -6420(20) 63359(33) 72 C(4) 49635(25) 5859(12) 75154(15) 40 C(41 ) 41960(40) 191(19) 82425(24) 62 C(4a) 60761(24) 12836(12) 81957(15) 36 C(4a1 ) 47429(35) 18757(16) 85213(23) 54 C(5) 74006(29) 9490(13) 92495(16) 41 C(6) 89347(27) 14904(13) 98534(16) 44 C(61 ) 98744(50) 11991(23) 109961(21) 69 C(7) 93887(28) 21435(13) 94122(17) 47 C(71 ) 108809(50) 27135(23) 99922(30) 78 C(8) 84279(33) 23770(14) 82623(19) 49 C(8a) 72905(25) 17195(12) 75529(15) 37 C(8a1 ) 62208(36) 20932(18) 64595(20) 54 0(1 ) 101829(19) 12595(10) 73321(14) 64 0(4) 34349(19) 8803(10) 66657(12) 51 71 Table XI (continued) H1 (21 ) 81 8 ( 6) -26( 2) 549( 4) 145(14) H2(21) 903( 6) -68( 3) 646( 4) 150(18) H3(21) 989( 8) 13( 3) 61 2 ( 4) 182(20) H1(31 ) 384( 5) -65( 2) 623( 2) 93(10) H2(31 ) 552( 6) -1 08 ( 2) 680( 3) 127(15) H3(31) 545( 5) -71 ( 2) 562( 3) 110(12) H1(41 ) 353( 3) 33( 1) 871 ( 2) 64( 7) H2(41) 327( 4) -35( 2) 777( 2) 79( 9) H3(41) 523( 4) -32( 2) 873( 2) 73( 8) H1(04) 246( 4) 95( 2) 690( 2) 86( 9) H1(4a1 ) 380( 4) 1 57 ( 2) 884( 2) 74( 7) H2(4a1 ) 539( 4) 228( 2) 900( 2) 66( 8) H3(4a1 ) 398( 4) 21 5( 2) 788( 2) 75( 8) H1 (5) 795( 3) 44( 1 ) 908( 2) 43( 5) H2(5) 668( 3) 79( 1 ) 975( 2) 61( 7) H1(61 ) ' 1 008( 5) 61 ( 2) 1 1 03 ( 3) 123(13) H2(61) 1096( 6) 1 37( 2) 1 1 22 ( 4) 136(17) H3(61 ) 91 8 ( 7) 1 35 ( 3) 1 1 60 ( 4) 161(18) H1(71 ) 1 1 79 ( 6) 277 ( 2) 960( 4) 128(16) H2(71 ) 1 036 ( 6) 329( 3) 977( 4) 166(19) H3(71 ) 1 1 39 ( 6) 259( 2) 1074( 4) 137(15) H1 (8) 931 ( 4) 254( 1) 790( 2) 63( 7) H2(8) 752( 3) 284( 1 ) 822( 2) 66( 7) HI (8aD 561 ( 4) 171 ( 2) 599( 2) 69( 9) H2(8a1 ) 7 1 2 ( 4) 233( 2) 6 1 0 ( 3) 99(10) H3(8a1 ) 533( 4) 251 ( 1) 655( 2) 71 ( 8) I 72 Table XII F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10" A 2) and t h e i r estimated standard d e v i a t i o n s Atom y i i y 2 2 U 3 3 y 1 2 y 1 3 y 2 3 C(1 ) 297( 10) 607(13) 337(10) -1 1 ( 9) 1 23 ( 8) 26( 9) C(2) 342( 10) 568(13) 379 ( 10)- 68( 9) 97( 8) -54( 10) C(21 ) 543( 16) 913(24) 657(17) 1 26 ( 15) 205( 14) -268( 17) C(3) 385( 11) 447(12) 408(11) -1 ( 9) 48( 9) -16( 9) C(31 ) 662( 19) 640(19) 839(22) -1 26 ( 15) 149( 16) -205( 17) C(4) 270( 9) 523(12) 403(10) -29( 9) 97( 8) 46( 9) C(41 ) 534( 15) 753(18) 609(15) -232( 14) 202( 13) 52( 15) C(4a) 281 ( 9) 459(11) 360(10) 1 1 ( 8) 1 35 ( 8) -8( 8) C(4a1 ) 421 ( 13) 659(17) 572(15) 93( 12) 1 85 ( 12) -79( 14) C(5) 41 3( 1 1 ) 491(13) 344(10) 8( 10) 1 1 3( 9) 33( 9) C(6) 378( 1 1 ) 563(14) 371(10) 67( 10) 88( 9) -47( 10) C(61 ) 673( 19) 850(22) 432(14) 1 00 ( 17) -41 ( 13) 8( 14) C(7) 392( 11) 543(13) 454(12) -18( 10) 93( 9) -1 16( 10) C(71 ) 7 1 0 ( 20) 879(24) 688(20) -287( 17) 62( 17) -1 96 ( 18) C(8) 477( 13) 467(13) 550(13) -84( 11) 1 53 ( 11) 17( 1 1 ) C(8a) 3 1 8 ( 9) 434(11) 366(10) -28( 8) 99( 8) 37( 9) C(8a1 ) 494( 13) 627(17) 467(13) -30( 13) 83( 11) 1 44 ( 12) 0(1) 303( 8) 922(13) 755(11) -89( 8) 246( 8) -131 ( 9) 0(4) 254( 7) 777(11) 498( 8) 0( 7) 78( 6) 1 ( 8) 73 between the C(3)...H1(5) and the C(3)=C(2) v e c t o r s , A c, are 50° and 78.3(4)°, r e s p e c t i v e l y . T h i s geometry i s h i g h l y f a v o r a b l e f o r hydrogen a b s t r a c t i o n by the p-enone carbon and i t i s F i g u r e 12 Stereo diagram of 2 , 3,4a,4ap,6,8ap-heptamethyl- 4ap,5,8,8a£-tetrahydro-1-naphthoquin-4 0-ol t h e r e f o r e not s u r p r i s i n g that t h i s i s the dominant r e a c t i o n observed i n the s o l i d s t a t e p h o t o l y s i s (36). I r r a d i a t i o n i n s o l u t i o n a f f o r d s only the i n t r a m o l e c u l a r [2+2] c y c l o a d d i t i o n photoproduct, due to the presence of a high energy conformer not a v a i l a b l e i n the c r y s t a l l a t t i c e . I t i s i n t e r e s t i n g to note that oxygen a b s t r a c t i o n of a p - 74 hydrogen does not occur d e s p i t e molecular f u l f i l l m e n t of the geometric requirements. The p-H d e v i a t e s only 1° from the plane of the c a r b o n y l at a d i s t a n c e of 2.41(2) A from 0 ( 1 ) . The C=O...0-H angle of 82.7(6)° completes the almost p e r f e c t alignment of the p-H with the non-bonding o r b i t a l of 0 ( 1 ) . However, i t was argued i n the p r e v i o u s chapter that s u b s t i t u e n t s on the C(2) and C(3) p o s i t i o n s of the cyclohexenone moiety play a c r i t i c a l r o l e i n determining the photochemical r e a c t i o n pathway, p o s s i b l y by lowering the energy of the (rr, ir*) t r a n s i t i o n from which the carbon a b s t r a c t i o n of H1(5) i s c o n s i d e r e d to o r i g i n a t e . The lack of p-H a b s t r a c t i o n by oxygen in t h i s system lends support to the above argument but does l i t t l e to c l a r i f y the r o l e ( s ) of the C(2) and C(3) s u b s t i t u e n t s . Bond d i s t a n c e s , angles and t o r s i o n angles are presented i n Tables XIV, XV, XVI, XVII, XVIII, XIX, and XX. The former two q u a n t i t i e s g e n e r a l l y do not d e v i a t e s i g n i f i c a n t l y from accepted va l u e s (33) with the exception of bonds C(3)-C(4) and C(4)-C(4a) whose lengths of 1.531(3) A and 1.560(3) A, r e s p e c t i v e l y , are anomalously l a r g e compared to the same bonds in the c l o s e l y r e l a t e d hexamethyl-4c-ol d e r i v a t i v e (37). At present, no e x p l a n a t i o n i s o f f e r e d f o r these seemingly long bonds except to note the obvious d i f f e r e n c e between these two d e r i v a t i v e s being the a d d i t i o n a l methyl group on C(4) i n t h i s s t r u c t u r e . I t i s not expected that s t e r i c e f f e c t s alone, due to the i n t r o d u c t i o n of the C(41) methyl group would account f o r the i n c r e a s e i n the l e n g t h of the above bonds. Hydrogen bonding, found i n a l l the naphthoquinols s t u d i e d i n t h i s s e r i e s , i s present i n t h i s s t r u c t u r e as 0(4)-H...0(1) 75 i n t e r a c t i o n s l i n k i n g molecules along the a - a x i s ( F i g . 13), 0...0 = 2.855(2) A, H...0 = 1.99(3) A, 0-H...0 = 172(3)°. Comparison of Compounds ( I I I ) - ( V I I ) Comparisons of bond l e n g t h s and angles and t o r s i o n angles i n analogous tetrahydronaphthoquinones (34) and more r e c e n t l y i n tetra h y d r o n a p h t h o q u i n o l s (32) have r e v e a l e d the gross e f f e c t s of F i g u r e 13 Stereo packing diagram of 2,3,4o,4ap,6,8ap-heptamethyl- 4ap,5,8,8ap-tetrahydro-1-naphthoquin-4p-ol s u b s t i t u e n t s on the parent r i n g system. Many of the trends noted p r e v i o u s l y are c o r r o b o r a t e d i n the present comparison of an a d d i t i o n a l four t e trahydronaphthoquinol d e r i v a t i v e s . The 76 a p p r o p r i a t e i n f o r m a t i o n r e g a r d i n g the parent, u n s u b s t i t u t e d compound (32) has been reproduced (Tables XIII-XVI) to f a c i l i t a t e comparisons. A l l six-membered r i n g s adopt the h a l f - c h a i r conformation, p r e d i c t e d by Bucourt and Hainaut (38) as the most e n e r g e t i c a l l y s t a b l e conformation f o r both u n s u b s t i t u t e d and s u b s t i t u t e d cyclohexenes. Although the t e t r a h y d r o n a p h t h o q u i n o l s s t u d i e d thus f a r i n c l u d e examples of OH-anti and OH-syn conformations, only the former are represented here f o r comparison with (VI) i n which, d e s p i t e the p s e u d o - a x i a l syn p o s i t i o n of the hydroxy group the conformation i s s i m i l a r t o the OH-anti compounds. Compounds ( I I I ) - ( V I I ) c o n s i s t of two c i s - f u s e d cyclohexene r i n g s , the carbon s k e l e t o n of which may be d e s c r i b e d by three approximate p l a n e s . Two planes c o n t a i n i n g atoms C(1) to C(4) and C(5) to C(8) make an angle of approximately 85° and subtend angles of c l o s e to 140° with respect to the t h i r d plane d e f i n e d by atoms C(4), C(4a), C(8a) and C ( 8 ) . The C(4)-C(4a)-C(8a)-C(8) t o r s i o n angles (Table XVI), averaging 175.7(5)°, i n d i c a t e the extent to which these atoms approximate a plane. T o r s i o n angles f o r the other planes range from -3.4(3)° to 2.3(5)°. S u b s t i t u e n t s on carbons C(4a) and C(8a) appear to have l i t t l e e f f e c t on the bridgehead t o r s i o n angle R 2-C(4a)-C(8a)-R 2 (Table XVI) which remains f a i r l y c o n s t a n t , averaging -63° f o r compounds ( I I I ) - ( V I I ) . However, the i n t e r n a l t w i s t angle, C ( l ) - C(8a)-C(4a)-C(5) decreases by c a . 5° upon methyl s u b s t i t u t i o n at the bridgehead carbons (compound ( V I ) ) ; s i m i l a r r e s u l t s were observed i n s e v e r a l naphthoquinone d e r i v a t i v e s (34) and i n other naphthoquinols (32). Whether t h i s i n t e r n a l t o r s i o n a l decrease 77 Table XIII D e r i v a t i v e s whose s t r u c t u r e s have been de t e r m i n e d 2 , with molecular conformations, parameters r e l e v a n t to photochemical a c t i v i t y , and hydrogen bond d i s t a n c e s ( d i s t a n c e s i n Angstroms and angles i n degrees). Compound (VII) (IV) (V) ( I I I ) (VI) R i H Me H Me Me R 2 H H H H Me R 3 H H H H H R. H H Me Me Me R 5 H H H H OH R 6 OH OH OH OH Me H 7 6 2 8a 4a O 2 3 / R 1 R 4 f \ ' *2 4 R1 H R_ R_ R-. 3 D D A, 3 Conformation common to a l l a n t i d e r i v a t i v e s (the b u l k i e r group on C(4) i s a n t i to bridgehead s u b s t i t u e n t s ) 2 Information r e g a r d i n g (VII) has been obtained from r e f e r e n c e 32. T a b l e X I I I ( c o n t i n u e d ) I n t r a m o l e c u l a r g e o m e t r i e s * ( V I I ) ( I V ) ( V ) C ( 2 ) . . . H 1 ( 5 ) 2 9 4 ( 2 ) 2 . . 9 2 ( 4 ) 2 . 9 2 ( 3 ) T c ( 2 ) 5 2 . 1 5 2 o 5 3 . 8 A c ( 2 ) 71 . 3 ( 3 ) 7 3 2 ( 7 ) 7 2 . 5 ( 7 ) C ( 3 ) . . . H 1 ( 5 ) 2 8 1 ( 2 ) 2 . 8 4 ( 4 ) 2 . 8 2 ( 3 ) 5 5 , , 7 5 4 . 1 5 6 . 7 0 . . . H 1 8 2 . 2 ( 4 ) 7 9 . 7 ( 8 ) 8 0 . 9 ( 7 ) ( 8 ) 2 . 4 9 ( 2 ) 2 . 4 9 ( 4 ) 2 . 4 9 ( 4 ) ro 0 . 6 1 4 Ao 8 1 8 ( 5 ) 8 3 ( 1 ) 8 1 ( 1 ) C ( 3 ) . . . C ( 6 ) 4 . 3 8 1 ( 2 ) 4 . 4 4 2 ( 5 ) 4 . 3 9 7 ( 6 ) C ( 2 ) . . C ( 7 ) 4 . 3 9 2 ( 2 ) 4 . 4 2 7 ( 5 ) 4 . 4 2 7 ( 6 ) d i 4 . 3 5 4 . 4 0 4 . 3 7 C O ) . . C ( 6 ) 3 . 4 0 4 ( 2 ) 3 . 3 7 9 ( 5 ) 3 . 4 1 4 ( 5 ) 0 ( 1 ) . . . C ( 7 ) 3 . 3 9 5 ( 2 ) 3 . 3 3 2 ( 4 ) 3 . 4 1 9 ( 5 ) e 8 9 8 8 9 0 d , 3 . 3 5 3 . 3 0 H y d r o g e n 3 . 3 6 b o n d 1 n g 0 ( 1 ) . . . 0 ( 4 ) - 0 ( 4 ) . . . 0 ( 4 ) 2 . 7 4 7 ( 3 ) 2 . 8 3 0 ( 2 ) 2 . 7 8 3 ( 2 ) 2 . 8 3 3 ( 3 ) P r i m a r y p h o t o c h e m i c a l r e a c t i o n * S o l u t i o n ( 1 ) ( 1 ) ( 1 ) S o l 1 d s t a t e ( 2 . 3 ) ( 2 ) ( 2 . 3 ) ( I I I ) 2 . 9 1 ( 5 ) 5 1 . 7 7 3 ( 1 ) 2 . 8 4 ( 5 ) 5 3 . 5 7 9 ( 1 ) 2 . 5 8 3 8 9 4 . 4 5 7 ( 3 ) 4 . 4 5 7 ( 3 ) 4 . 4 2 3 . 4 1 5 ( 3 ) 3 . 4 8 7 ( 5 ) 8 7 3 . 3 8 2 . 6 5 2 ( 5 ) 2 . 8 0 4 ( 2 ) ( V I ) 2 . 8 6 ( 2 ) 4 8 . 9 7 4 . . 5 ( 4 ) 2 8 1 ( 2 ) 5 0 . 0 7 8 . 3 ( 4 ) 2 . 4 1 ( 2 ) 1 8 2 7 ( 6 ) 4 . 4 5 3 ( 3 ) 4 . 4 1 9 ( 3 ) 4 . 4 0 3 . 2 9 3 ( 3 ) 3 . 2 1 7 ( 3 ) 9 8 3 . 1 9 2 . 8 5 5 ( 2 ) ( 1 ) ( 2 ) ( 1 ) ( 2 ) T a b l e X I I I ( c o n t i n u e d ) * F o r t h e C . . . H I n t e r a c t i o n s fl_ 1 s t h e C = C . . . H a n g l e a n d r 1 s t h e a n g l e b e t w e e n t h e C . . . H v e c t o r a n d t h e e n o n e p l a n e c c d e f i n e d b y C ( 1 ) - C ( 2 ) = C ( 3 ) - C ( 4 ) . F o r t h e 0 . . . H I n t e r a c t i o n s A Q I s t h e C = O . . . H a n g l e a n d r Q I s t h e a n g l e b e t w e e n t h e 0 . . . H v e c t o r a n d t h e c a r b o n y l m e a n p l a n e , d i I s t h e C=C c e n t e r - t o - c e n t e r d i s t a n c e a n d d ? 1 s t h e C = 0 , C ( 6 ) = C ( 7 ) c e n t e r - t o - c e n t e r d i s t a n c e . 9 1 s t h e a n g l e b e t w e e n t h e n o r m a l s t o t h e c a r b o n y l a n d t h e C ( 5 ) - C ( 6 ) = C ( 7 ) - C ( 8 ) m e a n p l a n e s . * * ( 1 ) I n t r a m o l e c u l a r [ 2 + 2 ] c y c l o a d d l 1 1 o n . ( 2 ) H - a b s t r a c t I o n b y t h e p - e n o n e c a r b o n C ( 3 ) . ( 3 ) H - a b s t r a c t I o n b y t h e c a r b o n y l o x y g e n 0 ( 1 ) . 80 without a concomitant e x t e r n a l i n c r e a s e i s due to h y b r i d i z a t i o n or s t e r i c e f f e c t s i s s t i l l not c l e a r . G e n e r a l l y , i n c r e a s e d s u b s t i t u t i o n i n the naphthoquinols r e s u l t s i n an enlarged r i n g s i z e . T h i s i s e v i d e n t i n the i n c r e a s e s i n s e v e r a l bond l e n g t h s and angles (Tables XIV and XV). The C(2)=C(3) bond i n compounds ( I I I ) and (IV) has a mean value of 1.345 A which i s 0.019 A longer than the same but u n s u b s t i t u t e d bond in the parent compound, ( V I I ) . The C(2)=C(3) bond in (VI) a l s o appears to be lengthened, although the d i f f e r e n c e from (VII) i s not d e f i n i t e l y s i g n i f i c a n t i n t h i s case (2.5*). S u b s t i t u e n t s at p o s i t i o n s C(2) and C(3) a f f e c t the C ( 2 ) - C d ) - C ( 8 a ) and C( 3)-C (4 )-C( 4a) angles by e n l a r g i n g them m a r g i n a l l y (<1.4°) with concomitant decreases i n the i n t e r n a l C(2)=C(3) double bond a n g l e s . S i m i l a r s u b s t i t u e n t - a s s o c i a t e d e f f e c t s are apparent at the C(6)=C(7) end of the r i n g . With methyl s u b s t i t u e n t s at p o s i t i o n s C(6) and C(7), the C(6)=C(7) double bond i s lengthened by an average of 0.016 A compared to the same bond in (VII) where hydrogens are the s u b s t i t u e n t s . Compound ( V I ) , whose C(6)=C(7) bond l e n g t h i s e s s e n t i a l l y the same as that i n (VII) does not seem to f o l l o w t h i s t r e n d . The angles C(4a)-C(5)-C(6) and C(7)-C(8)-C(8a) show an increase of 1.4-4.6° f o r R„=Me, whereas the i n t e r n a l angles C(5)-C(6)=C(7) and C(6)=C(7)-C(8) g e n e r a l l y decrease by 0.9-3.2° f o r the same s u b s t i t u t i o n . I t i s apparent from the above comparison that the i n c r e a s e i n the i n t e r n a l angles i n v o l v i n g the oxygen-bearing carbons as v e r t i c e s i s due mainly to s u b s t i t u t i o n at the double- bonded carbons and not to the bridgehead s u b s t i t u e n t s (32). I t i s not c l e a r , however, why the double-bond d i s t a n c e s i n (VI) do 81 not f o l l o w the trend observed f o r the s u b s t i t u t e d , double bonds of other d e r i v a t i v e s (c_f. 32). I t i s observed i n compounds ( I I I ) - ( V I ) that methyl s u b s t i t u t i o n at the double bond tends to i n c r e a s e the s i n g l e - bond l e n g t h s between the s u b s t i t u t e d double-bond carbons and the adjacent r i n g carbons. These bonds average 0.014 A g r e a t e r than the r e l a t e d bonds i n the parent compound. The C(5)-C(6) d i s t a n c e of 1.484(3) A i n ( I I I ) seems anomalous with res p e c t to the above tre n d ; however, t h i s may be a r e s u l t of i m p e r f e c t i o n s i n the model owing to the d i s o r d e r i n that s t r u c t u r e . Methyl s u b s t i t u t i o n at C(2) and C(3) a f f e c t s the e x t e r n a l angles C ( 2 ) - C(1)-0(1) and C(3)-C(4)-0(4) by widening them 0.5-0.7° and 1.9- 3.9°, r e s p e c t i v e l y . T h i s i s a t t r i b u t e d to s t e r i c e f f e c t s between the oxygens and the bulky methyl groups. The tendency f o r the methyl groups to bend away from each other i s " - l i m i t e d by the opposing oxygen atoms which l i e n e a r l y i n the same plane. Molecules w i t h i n c r y s t a l s of each of the compounds ( I I I ) - (VII) are l i n k e d by hydrogen bonding. Molecules of (IV) and (V) are j o i n e d v i a 0(4)...0(4) whereas (VI) i s l i n k e d by 0 ( 4 ) - H...0(1) i n t e r a c t i o n s . Due to the d i s o r d e r i n ( I I I ) , i t i s d i f f i c u l t to d i s c e r n the a c t u a l type of hydrogen bonding, but i t has been suggested (see Chapter I, D i s c u s s i o n ) that the two types, 0(4)...0(4) and 0(4)...0(1) are o p e r a t i v e . The parent compound (VII) e x h i b i t s 0(4)...0(4) i n t e r m o l e c u l a r hydrogen bonding through d i s o r d e r e d h y d r o x y l hydrogen atoms (32). The photochemistry of these compounds in s o l u t i o n and the s o l i d s t a t e has been d i s c u s s e d elsewhere (29,30,36,39). Compounds ( I I I ) - ( V I I ) a l l r e a c t - in the s o l i d s t a t e . The T a b l e X I V . B o n d d i s t a n c e s ( A ) w i t h e . s . d . ( V I I ) ( I V ) C ( 1 ) - C ( 2 ) 1 . 4 6 7 ( 2 ) 1 . 4 7 1 ( 5 ) C ( 2 ) - C ( 3 ) 1 . 3 2 6 ( 2 ) 1 . 3 5 1 ( 5 ) C O ) - C ( 4 ) 1 . 4 9 9 ( 2 ) 1 . 5 1 4 ( 5 ) C ( 4 ) - C ( 4 a ) 1 . 5 2 4 ( 2 ) 1 . 5 1 8 ( 5 ) C ( 4 a ) - C ( 5 ) 1 . 5 2 7 ( 2 ) 1 . 5 3 0 ( 5 ) C ( 5 ) - C ( 6 ) 1 . 4 9 7 ( 2 ) 1 . 4 9 7 ( 5 ) C ( 6 ) - C ( 7 ) 1 . 3 1 7 ( 2 ) 1 . 3 1 0 ( 5 ) C ( 7 ) - C ( 8 ) 1 . 4 9 0 ( 2 ) 1 . 4 8 9 ( 6 ) C ( 8 ) - C ( 8 a ) 1 . 5 1 8 ( 2 ) 1 . 5 2 5 ( 6 ) C ( 8 a ) - C ( 1 ) 1 . 5 1 6 ( 2 ) 1 . 5 1 2 ( 5 ) C ( 8 a ) - C ( 4 a ) 1 . 5 3 7 ( 2 ) 1 . 5 3 3 ( 5 ) C ( 1 ) - 0 ( 1 ) 1 . 2 1 6 ( 2 ) 1 . 2 2 1 ( 4 ) C ( 4 ) - 0 ( 4 ) 1 . 4 2 6 ( 2 ) 1 . 4 3 8 ( 4 ) n p a r e n t h e s e s ( V ) 1 . 4 6 3 ( 6 ) 1 . 3 2 1 ( 5 ) 1 . 4 8 7 ( 6 ) 1 . 5 1 9 ( 6 ) 1 . 5 2 1 ( 6 ) 1 . 5 2 0 ( 6 ) 1 . 3 2 7 ( 5 ) 1 . 5 0 1 ( 6 ) 1 . 5 1 4 ( 5 ) 1 . 5 1 4 ( 6 ) 1 . 5 2 5 ( 5 ) 1 . 2 1 9 ( 4 ) 1 . 4 3 7 ( 5 ) f o r c o m p o u n d s ( I I I ) 1 . 4 8 4 ( 3 ) 1 . 3 3 9 ( 3 ) 1 . 5 0 5 ( 3 ) 1 . 5 1 4 ( 3 ) 1 . 5 1 5 ( 3 ) 1 . 4 8 4 ( 3 ) 1 . 3 3 9 ( 3 ) 1 . 5 0 5 ( 3 ) 1 . 5 1 4 ( 3 ) 1 . 5 1 5 ( 3 ) 1 . 5 3 3 ( 4 ) 1 . 1 9 9 ( 4 ) 1 . 3 5 6 ( 4 ) ( I I I ) - ( V I I ) ( V I ) 1 . 4 7 3 ( 3 ) 1 . 3 3 5 ( 3 ) 1 . 5 3 1 ( 3 ) 1 . 5 6 0 ( 3 ) 1 . 5 4 5 ( 3 ) 1 . 5 0 7 ( 3 ) 1 . 3 1 6 ( 3 ) 1 . 4 9 9 ( 3 ) 1 . 5 3 3 ( 3 ) 1 . 5 2 0 ( 3 ) 1 . 5 5 6 ( 2 ) 1 . 2 2 3 ( 2 ) 1 . 4 3 8 ( 2 ) T a b l e X V . B o n d a n g l e s ( ° ) w i t h e . s . d . ' s 1 n p a r e n t h e s e s f o r c o m p o u n d s ( I I I ) - ( V I I ( V I I ) ( I V ) ( V ) ( I I I ) ( V I C ( 2 ) - C O ) - C ( 8 a ) 1 16 7 ( 1 ) 1 17 5 ( 3 ) 1 16 7 ( 4 ) 1 16 6 ( 2 ) 1 18 1 ( 2 ) C ( 2 ) - C O ) - 0 ( 1 ) 1 2 0 5 ( 1 ) 1 2 1 2 ( 3 ) 1 2 0 6 ( 4 ) 1 16 6 ( 3 ) 12 1 0 ( 2 ) C ( 8 a ) - C O ) - 0 ( 1 ) 1 2 2 8 ( 1 ) 121 3 ( 3 ) 1 2 2 6 ( 4 ) 1 2 6 5 ( 3 ) 1 2 0 6 ( 2 ) C ( 1 ) - C ( 2 ) - C O ) 1 2 1 5 ( 1 ) 1 2 0 8 ( 3 ) 1 2 1 4 ( 5 ) 1 2 0 6 ( 2 ) 1 2 0 9 ( 2 ) C ( 2 ) - C O ) - C ( 4 ) 1 2 3 6 ( 1 ) 1 2 1 8 ( 3 ) 1 2 3 5 ( 4 ) 1 2 3 0 ( 2 ) 1 2 3 2 ( 2 ) C ( 3 ) - C ( 4 ) - C ( 4 a ) 1 1 2 0 ( 1 ) 1 1 3 9 ( 3 ) 1 1 1 9 ( 4 ) 1 13 7 ( 2 ) 1 1 3 1( 1 ) C O ) - C ( 4 ) - 0 ( 4 ) 1 0 9 4 ( 1 ) 1 1 1 3 ( 3 ) 1 0 8 1 ( 4 ) 1 13 3 ( 2 ) 1 0 3 5 ( 1 ) C ( 4 a ) - C ( 4 ) - 0 ( 4 ) 1 1 2 9 ( 1 ) 1 1 1 7 ( 3 ) 1 12 5 ( 3 ) 1 1 0 5 ( 2 ) 1 1 1 1 ( 2 ) C ( 4 ) - C ( 4 a ) - C ( 5 ) 1 1 3 0 ( 1 ) 1 1 3 6 ( 3 ) 1 1 3 6 ( 4 ) 1 14 2 ( 2 ) 1 0 9 5 ( 1 ) C ( 4 ) - C ( 4 a ) - C ( 8 a ) 1 0 9 6 ( 1 ) 1 0 9 2 ( 3 ) 1 0 9 6 ( 4 . ) 1 0 9 7 ( 2 ) 1 1 1 4 ( 1 ) C ( 8 a } - C ( 4 a ) - C ( 5 ) 1 1 1 KD 1 1 0 5 ( 3 ) 1 0 9 7 ( 4 ) 1 0 9 8 ( 1 ) 1 0 7 0 ( 1 ) C ( 4 a ) - C ( 5 ) - C ( 6 ) 1 12 2 ( 1 ) 1 1 2 2 ( 3 ) 1 14 1 ( 4 ) 1 16 6 ( 2 ) 1 16 81 2 ) C ( 5 ) - C ( 6 ) - C ( 7 ) 1 2 3 8 ( 1 ) 1 2 4 1 ( 3 ) 1 2 2 0 ( 4 ) 1 2 0 6 ( 2 ) 1 2 2 3 ( 2 ) C ( 6 ) - C ( 7 ) - C ( 8 ) 1 2 4 3 ( 1 ) 1 2 3 9 ( 4 ) 1 2 3 0 ( 4 ) 1 2 3 0 ( 2 ) 1 2 1 3 ( 2 ) C ( 7 ) - C ( 8 ) - C ( 8 a ) 1 1 1 8 ( 1 ) 1 1 1 8 ( 4 ) 1 13 2 ( 4 ) 1 13 7 ( 2 ) 1 15 7 ( 2 ) C ( 8 ) - C ( 8 a ) - C O ) 1 1 2 7 ( 1 ) 1 13 4 ( 3 ) 1 13 5 ( 4 ) 1 14 2 ( 2 ) 1 1 0 3 ( 2 ) C ( 8 ) - C ( 8 a ) - C ( 4 a ) 1 1 1 7 ( 1 ) 1 1 1 2 ( 3 ) 1 1 1 6 ( 4 ) 1 0 9 7 ( 2 ) 1 1 0 0 ( 2 ) C ( 4 a ) - C ( 8 a ) - C O ) 1 1 0 KD 1 0 9 5 ( 3 ) 1 1 0 0 ( 3 ) 1 0 9 8 ( 1 ) 1 0 7 4 2 ) C O ) - C ( 2 ) - C ( 2 1 ) 1 1 5 9 ( 4 ) 1 1 5 0 ( 2 ) 1 15 6 2 ) C ( 2 1 ) - C ( 2 ) - C O ) 1 2 3 3 ( 4 ) 1 2 4 4 ( 2 ) 1 2 3 41 2 ) C ( 2 ) - C O ) - C ( 3 1 ) 1 2 2 7 ( 4 ) 1 2 2 3 ( 2 ) 1 2 0 5 2 ) C ( 3 1 ) - C ( 3 ) - C ( 4 ) 1 15 5 ( 4 ) 1 14 7 ( 2 ) 1 16 2 2 ) C ( 5 ) - C ( 6 ) - C ( 6 1 ) 1 13 8 ( 5 ) 1 15 0 ( 2 ) 1 1 3 0 2 ) C ( 6 1 ) - C ( G ) - C ( 7 ) 1 2 4 1 ( 5 ) 1 2 4 4 ( 2 ) 1 2 4 6 2 ) C ( 6 ) - C ( 7 ) - C ( 7 1 ) 1 2 3 1 ( 5 ) 1 2 2 3 ( 2 ) 1 2 4 3 2 ) C ( 7 1 ) - C ( 7 ) - C ( 8 ) 1 13 9 ( 5 ) 1 14 7 ( 2 ) 1 14 4 2 ) 84 p e r t i n e n t g e o m e t r i c a l parameters are given i n Table X I I I , page 77. It has been suggested (26) that the i n t r a m o l e c u l a r hydrogen a b s t r a c t i o n by carbon or oxygen can occur over d i s t a n c e s as great as the sum of the van der Waals r a d i i of the two atoms i n v o l v e d . For carbon a b s t r a c t i o n of hydrogen the suggested upper l i m i t i s 2.90 A ( F (C) = 1.70 A, T (H) = 1.20 A) whereas, f o r — w — w « a b s t r a c t i o n by oxygen the l i m i t suggested i s 2.72 A (7 (0) = 1.52 A, "r (H) = 1.20 A ) . Table XIII shows C(2)...H — w — w d i s t a n c e s a l l g r e a t e r than the 2.90 A l i m i t while the C(3)...H d i s t a n c e s range from 2.81 A to 2.84 A. I m p l i c i t i n the above suggested l i m i t s i s the requirement of otherwise f a v o r a b l e r e a c t i n g geometry. T h i s i s i n d i c a t e d by the o r i e n t a t i o n of the o r b i t a l i n v o l v e d i n the a b s t r a c t i o n process r e l a t i v e to the p o s i t i o n of the a b s t r a c t a b l e hydrogen. Although the exact o r i e n t a t i o n of the a b s t r a c t i n g o r b i t a l with respect to the hydrogen atom to be a b s t r a c t e d i s not d i r e c t l y o b s e r vable, i t can be i n f e r r e d from the two angles r and A. In the a b s t r a c t i o n by carbon process T c i s the angle between the Cabs" * * Habs v e c t o r a n o " t h e plane of the C(2)=C(3) double bond (C(1), C ( 2 ), C(3), C ( 4 ) ) , and A_ i s the angle between the Cabs ,** Habs and the C(2)=C(3) v e c t o r s . Angles of 90° f o r both T C and A c imply the most f a v o r a b l e a b s t r a c t i n g geometry with the a b s t r a c t i n g C 2 p - o r b i t a l c o l l i n e a r with the v u l n e r a b l e hydrogen. A l l compounds, (III)-<VII) r e a c t v i a H1(5) a b s t r a c t i o n by the p- enone carbon C(3), although the T c v a l u e s i n Table XIII appear much l e s s than f a v o r a b l e . However, i t i s not unreasonable to expect 30-40° (rotation around the C(2)=C(3) double bond upon 85 (ff,ir*) e x c i t a t i o n (26, and r e f e r e n c e s t h e r e i n ) . R o t a t i o n i n a fa v o r a b l e sense y i e l d s a T_ value of c l o s e to 90° f o r the molecule i n the e x c i t e d s t a t e . The secondary s o l i d s t a t e r e a c t i o n observed i n (V) and (VII) r e s u l t s i n a dihydroxy 1,6-bonded product analogous to naphthoquinone products r e s u l t i n g from p-hydrogen a b s t r a c t i o n r e a c t i o n s (35). I n s p e c t i o n of Table XIII r e v e a l s the f a v o r a b l e geometry of a l l compounds f o r the occurrence of carb o n y l oxygen a b s t r a c t i o n of p-hydrogen with O...H s e p a r a t i o n s of l e s s than 2.58 A, and T q and A Q angles of 0° and 90°, r e s p e c t i v e l y ; T Q being the angle subtended by the O a b s. . .H g b s v e c t o r and the plane of the car b o n y l (0(1), C(1), C(2), C ( 8 a ) ) , and A Q being the angle between the O a b s. . .H a b s and the 0=C v e c t o r s . The i d e a l geometry i s based on the alignment of the a b s t r a c t a b l e hydrogen on C(8) and the n - o r b i t a l on the oxygen which l i e s i n the plane of the ca r b o n y l group and p e r p e n d i c u l a r to the double bond. However, only (V) and (VII) were observed to undergo t h i s type of r e a c t i o n . I t was suggested i n Chapter II that s u b s t i t u e n t s on the enone double bond and t h e i r e f f e c t s on the e x c i t e d s t a t e of the molecule may be the c r i t i c a l f e a t u r e i n determining the p r o b a b i l i t y of the above r e a c t i o n . No i n t r a m o l e c u l a r [2+2] c y c l o a d d i t i o n products are observed i n the s o l i d s t a t e , while i n s o l u t i o n , where co n f o r m a t i o n a l e q u i l i b r a t i o n i s f a c i l e , a l l compounds undergo t h i s r e a c t i o n . The absence of [2+2] c y c l o a d d i t i o n products i n the s o l i d s t a t e i s r a t i o n a l i z e d on the b a s i s of the remoteness of the double bonds and t h e i r askew o r i e n t a t i o n s . For the above compounds, the angle between the v e c t o r s C(6)=C(7) and C(3)=C(2) i s ca. 50° and T a b l e X V I . T o r s i o n a n g l e s ( ° ) w i t h ( V I I ) 1 C ( 1 ) - C ( 2 ) - C ( 3 ) - C ( 4 ) - 0 K2) C ( 2 ) - C ( 3 ) - C ( 4 ) - C ( 4 a ) - 2 0 8 ( 2 ) C ( 3 ) - C ( 4 ) - C ( 4 a ) - C ( 8 a ) 4 9 K D C ( 4 ) - C ( 4 a ) - C ( 8 a ) - C O ) - 5 8 K D C ( 4 a ) - C ( 8 a ) - C O ) - C ( 2 ) 3 8 6 ( 1 ) C ( 8 a ) - C O ) - C ( 2 ) - C ( 3 ) - 9 4 ( 2 ) C ( 4 a ) - C ( 5 ) - C ( 6 ) - C ( 7 ) - 1 2 9 ( 2 ) C ( 5 ) - C ( 6 ) - C ( 7 ) - C ( 8 ) - 1 2 ( 2 ) C ( 6 ) - C ( 7 ) - C ( 8 ) - C ( 8 a ) - 1 4 6 ( 2 ) C ( 7 ) - C ( 8 ) - C ( 8 a ) - C ( 4 a ) 4 3 6 ( 1 ) C ( 8 ) - C ( 8 a ) - C ( 4 a ) - C ( 5 ) - 5 8 4 ( 1 ) C ( 8 a ) - C ( 4 a ) - C ( 5 ) - C ( 6 ) 4 1 6 ( 1 ) R i - C ( 4 a ) - C ( 8 a ) - R ! - 6 3 ( 1 ) C ( 4 ) - C ( 4 a ) - C ( 8 a ) - C ( 8 ) 1 7 6 0 ( 1 ) C ( 1 ) - C ( 8 a ) - C ( 4 a ) - C ( 5 ) 6 7 5 ( 1 ) C ( 3 ) - C ( 4 ) - C ( 4 a ) - C ( 5 ) - 7 5 4 ( 1 ) C ( 8 ) - C ( 8 a ) - C O ) - C ( 2 ) 1 6 4 0O) 0 ( 1 ) - C O ) - C ( 8 a ) - C ( 4 a ) - 1 4 3 0 ( 1 ) 0 ( 1 ) - C O ) - C ( 8 a ) - C ( 8 ) - 1 7 6 ( 2 ) 0 ( 1 ) -c(D - C ( 2 ) - C ( 3 ) 1 7 2 K D 0 ( 4 ) - C ( 4 ) - C ( 3 ) - C ( 2 ) - 1 4 6 7 ( 2 ) 0 ( 4 ) - C ( 4 ) - C ( 4 a ) - C ( 5 ) 4 8 6 ( 1 ) 0 ( 4 ) - C ( 4 ) - C ( 4 a ) - C ( 8 a ) 1 7 3 1 ( 1 ) C ( 1 ) - C ( 8 a ) - C ( 8 ) - C ( 7 ) - 8 0 9 ( 1 ) ' T o r s i o n a n g l e s f o r ( V I I ) r e f e r t o t h e e n a n t l o m e r o f e . s . d . ' s 1 n p a r e n t h e s e s f o r c o m p o u n d s ( 1 1 1 ) - ( V I I ) ( I V ) ( V ) ( I I I ) ( V I ) - 0 5 ( 4 ) 2 3 ( 5 ) - 2 3 ( 3 ) - 3 4 ( 3 ) - 1 8 8 ( 4 ) - 2 3 1 ( 5 ) - 1 6 3 ( 3 ) - 9 8 ( 3 ) 4 8 2 ( 3 ) 5 0 4 ( 4 ) 4 6 5 ( 2 ) 4 0 9 ( 2 ) - 5 9 0 ( 3 ) - 5 8 0 ( 4 ) - 5 8 9 ( 2 ) - 5 7 4 ( 2 ) 4 2 0 ( 4 ) 3 8 5 ( 4 ) 4 2 0 ( 3 ) 4 6 3 ( 2 ) - 12 0 ( 4 ) - 1 0 4 ( 5 ) - 1 1 5 ( 3 ) - 1 6 5 ( 3 ) - 13 7 ( 4 ) - 12 9 ( 5 ) - 1 1 5 ( 3 ) - 1 3 9 ( 3 ) - 0 3 ( 5 ) - 2 7 ( 5 ) - 2 3 ( 3 ) - 1 6 ( 3 ) - 15 7 ( 5 ) - 13 6 ( 5 ) - 1 6 3 ( 3 ) - 1 5 6 ( 3 ) 4 5 0 ( 4 ) 4 4 7 ( 4 ) 4 6 5 ( 2 ) 4 6 4 ( 2 ) - 5 9 5 ( 3 ) - 5 9 5 ( 4 ) - 5 8 9 ( 2 ) - 5 7 9 ( 2 ) 4 2 6 ( 3 ) 4 3 0 ( 4 ) 4 2 0 ( 3 ) 4 3 1 ( 2 ) - 6 2 ( 3 ) - 6 5 ( 3 ) - 6 3 ( 3 ) - 6 2 7 ( 2 ) 1 7 4 8 ( 3 ) 1 7 5 1 ( 3 ) 1 7 4 9 ( 2 ) - 1 7 7 5 ( 2 ) 6 6 6 ( 3 ) 6 7 3 ( 4 ) 6 7 3 ( 3 ) 6 2 2 ( 2 ) - 7 5 6 ( 3 ) - 7 2 7 ( 4 ) - 7 7 K2) - 7 7 3 ( 2 ) 1 6 6 9 ( 3 ) 1 6 4 2 ( 4 ) 1 6 5 6 ( 2 ) 1 6 6 2 ( 2 ) - 1 3 9 8 ( 3 ) - 1 4 3 2 ( 4 ) - 1 4 5 2 ( 5 ) - 1 3 8 7 ( 2 ) - 15 0 ( 4 ) - 1 7 4 ( 5 ) - 2 1 6 ( 5 ) - 1 8 8 ( 3 ) 1 6 9 8 ( 4 ) 17 1 2 ( 4 ) 1 7 5 0 ( 4 ) 1 6 8 5 ( 2 ) - 1 4 6 2 ( 3 ) - 1 4 7 6 ( 4 ) - 1 4 3 5 ( 3 ) 1 1 0 6 ( 2 ) 5 1 6 ( 3 ) 4 9 3 ( 4 ) 5 1 5 ( 3 ) 1 6 6 8 ( 1 ) 1 7 5 4 ( 3 ) 1 7 2 4 ( 3 ) 1 7 5 2 ( 2 ) - 7 5 0 ( 2 ) - 7 8 9 ( 4 ) - 8 0 2 ( 4 ) - 7 7 1 ( 2 ) - 7 2 0 ( 2 ) 00 t h e p a r e n t c o m p o u n d 1 n G r e e n h o u g h a n d T r o t t e r , 1 9 8 1 ( 3 2 ) . o\ 87 t h e i r double bond c e n t e r - t o - c e n t e r s e p a r a t i o n s are >4.3 A. S i m i l a r l y , unfavorable [2+2] i n t r a m o l e c u l a r c y c l o a d d i t i o n geometries e x i s t f o r the C=0 and C(6)=C(7) double bonds (Table X I I I ) . Table XVII Supplementary bond lengths (A) and angles (°) f o r compound (VI) with e.s.d.'s in parentheses Bond Length C(2) -C(21) 1 .514(3) C(3) -C(3 1 ) 1 .509(3) C(4) -C(41 ) 1 .539(3) C(4a) -C(4a1) 1 .541(3) C(6) -C(61) 1 .516(3) C(7) -C(71) 1 .508(3) C(8a) - C ( 8 a 1 ) 1 .541(3) Bonds Angle C(3) -C(4) -C(41) 109. 4(2) C(41 ) -C(4) -C(4a) 1 1 1 . 3(2) C(41 ) -CC4) -0(4) 108. 2(2) C(4) -C(4a) -C(4a1) 110. 1 (2) C(4a1 ) -C(4a) -C(5) 108. 5(2) C(4a1 ) -C(4a) -C(8a) 110. 3(2) C(1 ) -C(8a) - C ( 8 a 1 ) 105. 6(2) C(4a) rC(Ba) - C ( 8 a 1 ) 115. 2(2) C(8) -C(8a) -C(8a1) 108. 2(2) 89 Table XVIII « Bond lengths i n v o l v i n g hydrogen atoms (A) i n compound (VI) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(21 ) -H1 (21 ) 0 .95(4) C(5) . -H2(5) 0 .97(2) C(21 ) -H2(21) 0 .94(4) C(61 ) -H1(61 ) 1 .00(4) C(21 ) -H3(21) 0 .91(5) C(61 ) -H2(61 ) 0 .84(4) C(31 ) -H1(31 ) 0 .99(3) C(61 ) -H3(61) 1 .06(5) C(31 ) -H2(31 ) 0 .93(4) C(71) -H1(71) 0 .95(4) C(31 ) -H3(31 ) 0 .98(4) C(71 ) -H2(71) 1 .05(5) C (4 1) -H1(41 ) 1 .02(2) C(71 ) -H3(71) 0 .95(5) C(41 ) ~H2(41 ) 1 .00(3) C(8) -H1(8) 0 .94(3) C(41 ) -H3(41 ) 1 .03(3) C(8) -H2(8) 1 .02(2) C(4a1 )-H1(4a1) 1 .03(3) C(8a1) -H1(8a1) 0 .92(3) C(4a1 )-H2(4a1 ) 0 .96(3) C(8a1) -H2(8a1) 0 .99(3) C(4a1 )-H3(4a1) 0 .98(3) C(8a1) - H 3 ( 8 a 1 ) 1 .00(3) C(5) -H1(5) 1 .01(2) 0(4) -H1(04) 0 .87(3) 90 Table XIX Bond angles (deg) i n v o l v i n g hydrogen atoms i n compound (VI) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle C(2) -C(21) -H1(21) 109(2) C(2) -C(21) -H2(21) 112(3) C(2) -C(21) -H3(21) 112(3) H1 (21 ) -C(21) -H2(21) 97(3) H1 (21 ) -C(21) -H3(21) 104(4) H2(21) -C(21) -H3(21) 121(4) C(3) -C(31) -H1(31) 113(2) C(3) -C(31) -H2(31) 111(3) C(3) -C(31) -H3(31) 111(2) H1(31) -C(31) -H2(31) 99(3) H1(31 ) -C(31) -H3(31) 108(3) H2(31) -C(31) -H3(31) 115(3) C(4) -C(41) -H1(41) 110.4( 14) C(4) -C(41) -H2(41) 110(2) C(4) -C(41) -H3(41) 1 1 1 .1 ( 14) H1 (41 ) -C(41) -H2(41) 107(2) H1 (41 ) -C(41) -H3(41) 110(2) H2(41) -C(41) -H3(41) 108(2) C(4a) -C(4a1 )-H1(4a1 ) 110.4< 14) C(4a) -C(4a1 )-H2(4a1 ) 111.81 15) C(4a) -C(4a1 )-H3(4a1 ) 110.71 15) H1 (4a1)-C(4a1)-H2(4a1)113(2) HI(4a1)-C(4a1)-H3(4a1)104(2) H2(4a1)-C(4a1)-H3(4a1)107(2) C(4a) -C(5) -H1(5) 109.3( 11) C(4a) -C(5) -H2(5) 108.91 13) C(6) -C(5) -H1(5) 109.0< 1 1 ) Bonds Angle C(6) -C(5) -H2(5) 108.0(13) H1 (5) -C(5) -H2(5) 104(2) C(6) -C(61) -H1(61) 113(2) C(6) -C(61) -H2(61) 112(3) C(6) -C(61) -H3(61) 115(2) H1(61) -C(61) -H2(61) 102(3) H1(61) -C(61) -H3(61) 108(3) H2(61) -C(61) -H3(61) 107(4) C(7) -C(71) -H1(71) 111(2) C(7) -C(71) -H2(71) 106(2) C(7) -C(71) -H3(71) 113(3) H1(71 ) -C(71) -H2(71) 92(3) H1(71 ) -C(71) -H3(71) 113(3) H2(71 ) -C(71) -H3(71) 120(4) C(7) -C(8) -H1(8) 109.4(15) C(7) -C(8) -H2(8) 113.2(14) C(8a) -C(8) -H1(8) 106.0(15) C(8a) -C(8) -H2(8) 104.6(13) H1 (8) -C(8) -H2(8) 1 07(2) C(8a) -C(8a1) -H1(8a1) 111(2) C(8a) -C(8a1) -H2(8a1) 109(2) C(8a) -C(8a1) -H3(8a1) 1 12.8(15) H1(8a1)-C(8a1)-H2(8a1)105(2) H1(8a1)-C(8a1)-H3(8a1)109(2) H2(8a1)-C(8a1)-H3(8a 109(2) C(4) -0(4) -H1(04) 112(2) I 91 Table XX Supplementary t o r s i o n angles (deg) f o r compound (VI) with estimated standard d e v i a t i o n s i n parentheses Atoms Value C ( 8 a ) -CO ) -C(2) -C(21) 162.5(2) 0(1 ) -CO) -C(2) -C(21) -12.5(3) C(2) -CO ) - C ( 8 a ) - C ( 8 a 1 ) -77.2(2) 0(1 ) -CO ) - C ( 8 a ) - C ( 8 a 1 ) 97.9(2) C O ) -C(2) -C(3) -C(31) 174.7(2) C(21 ) -C(2) -C(3) -C(31) -4.2(4) C(21 ) -C(2) -C(3) -C(4) 177.7(2) C(2) -C(3) -C(4) -C(41) -134.3(2) C(31 ) -C(3) -C(4) -C(41) 47.5(3) C(31 ) -C(3) -C(4) -C(4a) 172.1(2) C(31 ) -C(3) -C(4) -0(4) -67.6(3) C(3) -C(4) -C(4a) -C(4a1) 163.6(2) C(41 ) -C(4) -C(4a) -C(4a1) -72.9(2) C(41 ) -C(4) -C(4a) -C(5) 46.2(2) C(41 ) -C(4) -C(4a) - C ( 8 a ) 164.4(2) 0(4) -C(4) -C(4a) -C(4a1) 47.7(2) C(4a1 )-C(4a) -C(5) -C(6) -75.9(2) C(4) -C(4a) - C ( 8 a ) - C ( 8 a 1 ) 59.9(2) C(4a1 )-C(4a) - C ( 8 a ) -CO ) -180.0(2) C(4a1 )-C(4a) - C ( 8 a ) -C(8) 59.9(2) C(4a1 )-C(4a) - C ( 8 a ) - C ( 8 a 1 ) -62.7(2) C(5) -C(4a) - C ( 8 a ) - C ( 8 a 1 ) 179.5(2) C(4a) -C(5) -C(6) -C(61) 166.4(2) C(5) -C(6) -C(7) -C(71) 178.5(2) C(61 ) -C(6) -C(7) -C(71) -1.8(4) C(61 ) -C(6) -C(7) -C(8) 178. 1(2) C(71 ) -C(7) -C(8) - C ( 8 a ) 164.4(2) C(7) -C(8) - C ( 8 a ) - C ( 8 a 1 ) 173.0(2) C O ) -C(2) -C(21) -H1(21) -124(3) C O ) -C(2) -C(21) -H2(21) 130(3) C O ) -C(2) -C(21) -H3(21) -9(4) C(3) -C(2) -C(21) -H1(21) 55(3) C(3) -C(2) -C(21) -H2(21) -51(3) C(3) -C(2) -C(21) -H3(21) 170(4) C(2) -C(3) -C(31) -H1(31) -159(2) C(2) -C(3) -C(31) -H2(31) 91(3) C(2) -C(3) -C(31) -H3(31) -38(2) C(4) -C(3) -C(31) -H1(31) 19(2) C(4) -C(3) -C(31) -H2(31) -91(3) C(4) -C(3) -C(31) -H3(31) 140(2) C(3) -C(4) -C(41) -H1(41) 175.6(15) C(3) -C(4) -C(41) -H2(41) -66(2) C(3) -C(4) -C(41) -H3(41) 53.0(15) Table XX (continued) C(4a) -c( 4) -c( 41) -H1(41) 50. 0( 15) C(4a) -c( 4) -c( 41) -H2(41) 1 68 ( 2) C(4a) -c( 4) -c( 41) -H3(41) -72. 6( 15) 0(4) -c( 4) -c( 41) -H1(41) -72. 3( 15) 0(4) -c( 4) -c( 41) -H2(41) 46( 2) 0(4) -c( 4) -c( 41) -H3(41) 165. 0( 15) C(3) -c( 4) -o( 4) -H1(04) 151 ( 2) C(41 ) -c( 4) -o( 4) -H1(04) 35( 2) C(4a) -c( 4) -o( 4) -H1(04) -87( 2) C(4) -c( 4a) -c( 4a 1 ) -H1(4a1) 48( 2) C(4) -c( 4a) -c( 4a 1 ) -H2(4a1) 1 74 ( 2) C(4) -c( 4a) -C( 4a 1 ) -H3(4a1) -67( 2) C(5) -c( 4a) -c( 4a 1 ) -H1(4a1 ) -72( 2) C(5) -c( 4a) -C( 4a 1 ) -H2(4a1) 54( 2) C(5) -c< 4a) -C( 4a 1 ) -H3(4a1) 1731 2) C(8a) -c< 4a) -CI 4a 1 ) -H1(4a1) 171 . 2( 15) C(8a) -CI 4a) -CI 4a 1 ) -H2(4a1) -62( 2) C(8a) -c< 4a) -CI 4a 1 ) -H3(4a1) 561 2) C(4) -CI 4a) -CI 5) -H1(5) 39. 7( 12) C(4) -c< 4a) -CI 5) -H2(5) -73. 4< 14) C(4a1) -c< 4a) -CI 5) -H1(5) 159. 8( 12) C(4a1) -c< 4a) -CI .5) -H2(5) 46. 7( 14) C(8a) -c ,4a) -CI [5) -H1(5) -81 . 1 ( 12) C(8a) -c [4a) -c [5) -H2(5) 165 8( 14) H1 (5) -c [5) -c [6) -C(61) -69 1 I 12) H1 (5) -c [5) -c [6) -C(7) 1 10 61 12) H2(5) -c [5) -c [6) -C(61) 43 -31 14) H2(5) -c [5) -c (6) -C(7) -1 37 .01 14) C(5) -c [6) -c [61 ) -H1(61) 41 [2] C(5) -c (6) -c [61 ) -H2(61) 1 55 [3] C(5) -c (6) -c (61 ) -H3(61) -83 (3.; C(7) -c (6) -c (61 ) -H1(61) -138 (2 C(7) -c (6) -c (61 ) -H2(61) -24 (3 C(7) -c (6) -c (61 ) -H3(61) 98 (3 C(6) -c (7) -c (71 ) -H1(71 ) 1 22 (3 C(6) -c (7) -c (71 ) -H2(71) -139 (3 C(6) -c (7) -c (71 ) -H3(71) -6 (3 C(8) -c (7) -c (71 ) -H1(71) -58 (3 C(8) -c (7) -c (71 ) -H2(71) 41 (3 C(8) -c (7) -c (71 ) -H3(71) 174 (3 C(6) -c (7) -c (8) -H1(8) -1 35 . 1 !15) C(6) -c (7) -c (8) -H2(8) 1 05 . 1 (14) C(71 ) -c (7) -c (8) -H1(8) 44 .8 (15) C(71 ) -c (7) -c (8) -H2(8) -75 .0 (14) H1 (8) -c (8) -c (8a) -CO) 49 .4 0 5 ) H1 (8) -c (8) -c (8a) -C(4a) 167 .8 05) H1 (8) -c (8) -c (8a) -C(8a1) -65 .6 0 5 ) H2(8) -c (8) -c (8a) -CO) 162 .8 0 4 ) H2(8) -c (8) -c (8a) -C(4a) -78 .8 0 4 ) H2(8) -c (8) -c (8a) -C(8a1) 47 .8 :u) C(1) -c (8a) -c (8a1 ) -H1(8a1) 57 (2 Table XX (continued) C O ) - C ( 8 a ) - C ( 8 a 1 >-H2(8a1) -59(2) C O ) - C ( 8 a ) - C ( 8 a 1 )-H3(8a1) 179.6(15) C ( 4 a ) - C ( 8 a ) - C ( 8 a 1 )-H1(8a1) -62(2) C ( 4 a ) - C ( 8 a ) - C ( 8 a 1 )-H2(8a1) -177(2) C ( 4 a ) - C ( 8 a ) - C ( 8 a 1 )-H3(8a1) 61 (2) C ( 8 ) - C ( 8 a ) - C ( 8 a 1 )-H1(8a1) 175(2) C ( 8 ) - C ( 8 a ) - C ( 8 a 1 )-H2(8a1) 59(2) C ( 8 ) - C ( 8 a ) - C ( 8 a 1 )-H3(8a1) -62(2) 94 CHAPTER IV 6,7-DIMETHYL-4a p,5,8,8ap-TETRAHYDRONAPHTHOQUIN-1o,4o-DIOL 95 I n t r o d u c t i o n The c r y s t a l l o g r a p h i c s t u d i e s presented thus f a r were, as p r e v i o u s l y d e s c r i b e d , embarked upon with the hope that the s t r u c t u r a l e l u c i d a t i o n would promote an understanding of the photochemical r e a c t i o n mechanism. While the present compound i s s i m i l a r to the naphthoquinols p r e v i o u s l y d i s c u s s e d , i t s c r y s t a l s t r u c t u r e was s t u d i e d f o r a d i f f e r e n t reason. O b t a i n i n g s i n g l e c r y s t a l s f o r X-ray d i f f r a c t i o n work has i n many cases been the determining f a c t o r i n whether or not the s o l i d s t a t e s t r u c t u r e i s s o l v e d . T h i s l i m i t a t i o n has l e d to a p r o j e c t of i n v e s t i g a t i n g s o l i d s t a t e s t r u c t u r e s by 13C-NMR spectroscopy. McDowell, N a i t o , S c h e f f e r and Wong (40), have i l l u s t r a t e d some advantages of t h i s technique over X-ray s t r u c t u r e a n a l y s i s i n t h e i r work on co n f o r m a t i o n a l a n a l y s i s of tetrahydronaphthoquinones. The technique of high r e s o l u t i o n s o l i d s t a t e 13C-NMR i s not d i s c u s s e d here, but some of the r e s u l t s achieved by i t s use are mentioned. In b r i e f , McDowell e_t a_l. have shown t h a t f o r the tetrahydronaphthoquinones, where c h e m i c a l l y e q u i v a l e n t carbons appear as s i n g l e t s i n s o l u t i o n , d o u b l e t s appear i n the s o l i d s t a t e . T h i s i s a t t r i b u t e d to the s l i g h t environmental d i f f e r e n c e s experienced by the carbons i n the s o l i d s t a t e . It was proposed that t h i s d i s c r i m i n a t i n g f e a t u r e of the s o l i d s t a t e c o u l d be e x p l o i t e d i n i d e n t i f y i n g s t r u c t u r a l l y independent molecules whose 13C-NMR s p e c t r a should be r e a d i l y d i s c e r n i b l e . Although the c h a r a c t e r i z a t i o n of the two s t r u c t u r a l l y independent molecules of u n s u b s t i t u t e d 4ap,5,8,8ap-tetrahydro- 96 1,4-naphthoquinone i n the s o l i d s t a t e was s u c c e s s f u l , such, was not the case f o r the present compound. The mu l t i t u d e of peaks i n the 13C-NMR spectrum suggested more than one independent molecule i n the s t r u c t u r e but the evidence d i d not unambiguously i n d i c a t e the exact number. S i n g l e c r y s t a l s of the t i t l e compound were o b t a i n a b l e and hence the d e s i r e to o b t a i n a complete s t r u c t u r a l d e termination by X-ray d i f f r a c t i o n techniques seemed c o m p e l l i n g . The c r y s t a l l o g r a p h i c a n a l y s i s was t h e r e f o r e undertaken i n an e f f o r t to e s t a b l i s h i ) the number of s t r u c t u r a l l y independent molecules, i i ) t h e i r i n d i v i d u a l conformations and i f they d i f f e r e d from each other and i i i ) to v e r i f y the isomer (with r e s p e c t to the OH p o s i t i o n s ) p r e s e n t . Of a d d i t i o n a l i n t e r e s t c r y s t a l l o g r a p h i c a l l y was how the present, f u l l y reduced s t r u c t u r e compared with d e r i v a t i v e s of 4ap,5,8,8ap-tetrahydro-1 - naphthoquin-4o-ol. Exper imental C o l o u r l e s s a c i c u l a r c r y s t a l s of the d i o l 1 (VIII) , were obtained from a hexanone/n-hexane s o l u t i o n by slow e v a p o r a t i o n . P r e l i m i n a r y p r e c e s s i o n photographs r e v e a l e d the systematic absences, 0k0, k = 2n + 1; hOl, 1= 2n + 1, i n d i c a t i v e of the space group P2,/c. C r y s t a l data: C 1 2 H 1 8 0 2 , MW = 194.28, monoclinic a = 13.870(2), 1 IUPAC name: 1o,4o-dihydroxy-6,7-dimethyl-1,4,4ap,5,8,8ap- hexahydronaphthalene. 97 b = 18.025(4), c = 9.236(1) A, * = 108.098(6)°, V = 2194.9(6) A 3, Z = 8, D = 1.176 g cm" 3, D = 1.T79 g cm" 3, ^(MoKa) — 5 = 0.436 cm - 1, X = 0.71073 A, space group P2,/c. ( V I I I ) Data were c o l l e c t e d with a c r y s t a l measuring 0.52 x 0.15 x 0.10 mm3 between t h e t a l i m i t s of 0.0 and 22.5° u s i n g ah u-2e scan and g r a p h i t e monochromatized MoKc r a d i a t i o n . The omega scan angle, (0.65 + 0.35tane)°, was extended by 25% on each s i d e of the peak f o r background measurement. The v e r t i c a l aperture remained constant at 4 mm whereas the h o r i z o n t a l a p e r t u r e was v a r i e d a c c o r d i n g to the e x p r e s s i o n (2.00 + tane) mm. Three r e f l e c t i o n s were des i g n a t e d as i n t e n s i t y c o n t r o l s and were measured every 3600 seconds of X-ray exposure time. O r i e n t a t i o n check r e f l e c t i o n s were p e r m i t t e d a d e v i a t i o n of up to 0.055° between observed and c a l c u l a t e d s c a t t e r i n g v e c t o r s before r e o r i e n t a t i o n was e f f e c t e d . Lorentz and p o l a r i z a t i o n c o r r e c t i o n s were a p p l i e d to the 2845 r e f l e c t i o n s c o l l e c t e d . F u r t h e r p r o c e s s i n g showed 51.4% (1461) of the data were c l a s s i f i e d as observed having I > 3<r(I), where * 2 ( I ) = S + 2B + (0.04(S - B ) ) 2 , S = scan count and B = 98 the time-averaged background. The decay i n the i n t e n s i t i e s of the three c o n t r o l r e f l e c t i o n s was n e g l i g i b l e over the p e r i o d of data c o l l e c t i o n . S o l u t i o n and Refinement The E - s t a t i s t i c s , c a l c u l a t e d f o r a l l the data, c l o s e l y p a r a l l e l e d the t h e o r e t i c a l c e n t r i c d i s t r i b u t i o n . The N(z) t e s t f i r m l y supported the c e n t r i c d i s t r i b u t i o n , and s o r there e x i s t e d l i t t l e doubt concerning the space group assignment of _P2,/c_. In the i n i t i a l stages of MULTAN, 4709 E 2 - r e l a t i o n s h i p s were generated from 312 r e f l e c t i o n s having |E| > 1.588. The r e s u l t s of the E,-formula i n d i c a t e d the phases of four r e f l e c t i o n s , with each i n d i c a t i o n having a p r o b a b i l i t y g r e a t e r than the acceptance value of 0.95 and having more than 15 c o n t r i b u t o r s . The phases a s s o c i a t e d with the three o r i g i n d e f i n i n g r e f l e c t i o n s , chosen i n accordance with space group symmetry, the four known phases, from the E, r e s u l t s and f i v e other phases a s s o c i a t e d with r e f l e c t i o n s common to many r e l a t i o n s h i p s i n the E 2 _ l i s t i n g made up the s t a r t i n g s e t . T h i s set of phases was the only one developed and gave e x c e l l e n t f i g u r e s of m e r i t . Using E's as the c o e f f i c i e n t s i n the th r e e - d i m e n s i o n a l F o u r i e r s y n t h e s i s , an i n t e r p r e t a b l e e l e c t r o n d e n s i t y map was c a l c u l a t e d from which the f r a c t i o n a l c o o r d i n a t e s f o r a l l non-hydrogen atoms were obtained. The peaks on the E-map, when j o i n e d i n a c h e m i c a l l y s e n s i b l e manner, corresponded to two c r y s t a l l o g r a p h i c a l l y independent molecules thereby s u b s t a n t i a t i n g the i m p l i c a t i o n from d e n s i t y measurements of there being e i g h t molecules i n the u n i t c e l l . 39 In the i n i t i a l stages of refinement, only non-hydrogens were i n c l u d e d and were assig n e d i s o t r o p i c thermal parameters. L a t e r , a n i s o t r o p i c temperature f a c t o r s were i n c o r p o r a t e d i n t o the refinement of the carbons and oxygens, a f t e r which a d i f f e r e n c e - F o u r i e r s y n t h e s i s r e v e a l e d the p o s i t i o n s of the 36 hydrogen atoms. Two a d d i t i o n a l peaks, e q u i v a l e n t i n magnitude to the peaks a s s i g n e d H(01) and H(OI'), appeared on the e l e c t r o n d e n s i t y map. One peak was p o s i t i o n e d approximately 1 A from 0(1) and subtended an angle of roughly 112° with C ( 1 ) , 0(1) being the v e r t e x ; the other peak was p o s i t i o n e d s i m i l a r l y with respect to 0 ( 1 ' ) . These p o s i t i o n s were given occupancy f a c t o r s of 0.5 and r e f i n e d as hydrogens. The i n i t i a l l y a s s i g n e d H(01) and H(01') p o s i t i o n s a l s o assumed 0.5 occupancies d u r i n g the refinement. Thermal v i b r a t i o n s of hydrogens were c o n s i d e r e d to be i s o t r o p i c and r e f i n e d a c c o r d i n g l y . The f i n a l c y c l e of refinement v a r i e d 405 parameters which showed mean and maximum s h i f t s of 0.114 and 1.107©-, r e s p e c t i v e l y . An e r r o r of 1.619 was c a l c u l a t e d f o r an o b s e r v a t i o n of u n i t weight. F i n a l R-values were R = 0.032 and Rw = 0.035 f o r the 1461 observed data, while R = 0.104 and Rw = 0.035 f o r the e n t i r e data set c o n s i s t i n g of 2845 r e f l e c t i o n s . A d i f f e r e n c e s y n t h e s i s f o l l o w i n g convergence i n d i c a t e d random f l u c t u a t i o n s i n the e l e c t r o n d e n s i t y with the l a r g e s t peak cor r e s p o n d i n g to 0.124 e/A 3. The a b s o l u t e weights, w = 1/©- z(F ) , where o- 2(F) i s obtained from the p r e v i o u s l y d e f i n e d © 2 ( I ) , were employed i n the refinement. A l i s t of atomic c o o r d i n a t e s and temperature f a c t o r s i s presented i n Table XXI; a n i s o t r o p i c thermal parameters f o r non-hydrogen atoms are c o n t a i n e d i n Table XXII. 100 Table XXI F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10",H x 1 0 3 ) and i s o t r o p i c thermal parameters (U x 1 0 3 A 2) with estimated standard d e v i a t i o n s i n parentheses Atom 2 X 1 z Ueq/Uiso C O ) 2331 ( 3) 1 126( 2) 3501 ( 3) 49 C(2) 1501 ( 3) 952( 2) 2067( 4) 55 C(3) 647( 3) 1 320( 2) 1581 ( 4) 49 C(4) 407( 2) 1 964( 2) 2409( 3) 41 C(4a) 972( 2) 1922( 2) 4 1 03 ( 3) 35 C(5) 585( 3) 1 330( 2) 4946( 3) 43 C(6) 1 287 ( 3) 1 1 65 ( 2) 6529( 3) 46 C(61) 789( 5) 7 1 5( 3) 7482( 5) 74 C(7) 2242( 3) 1 393 ( 2) 7001 ( 3) 48 C(71 ) 2973( 4) 1 236 ( 3) 8559( 5) 78 C(8) 2706( 3) 1837 ( 2) 6001 ( 4) 53 C(8a) 2099( 2) 1 8 1 6 ( 2) 431 5( 3) 41 0(1 ) 2539( 3) 489( 1) 4464( 3) 70 0(4) -676( 2) 1 997 ( 1) 2042( 2) 51 C O ' ) -4175( 2) 801 ( 2) -2861( 3) 42 C(2' ) -3370( 3) 668( 2) -1378( 4) 51 C(3' ) -2615( 3) 1 1 28 ( 2) -783( 4) 49 C(4' ) -2493( 2) 1851 ( 2) -1491( 3) 39 C(4a') -3013( 2) 1848 ( 2) -3194( 3) 35 C(5' ) -2470( 2) 1 398( 2) -4087( 3) 38 C(6' ) -3095( 2) 1254( 2) -5716( 3) 42 C(61') -24901 4) 954( 3) -6685( 5) 63 C(7' ) -40841 3) 1376( 2) -6224( 3) 45 C(71 ' ) -4730< 4) 1 264 < 3) -7862( 5) 78 C(8' ) -46731 3) 1 637 < 2) -5200< 4) 51 C(8a') -41071 2) 1 574( 2) -3508I 3) 40 0(1 ' ) -4148 k 3) 1 99 < 1 ) -3851< 3) 49 0(4' ) -1440 : 2) 20461 1 ) -1 1 62 3) 51 HO ) 299( 2) 1 22 ( 1 ) 326( 3) 49( 8) H(2) 1 60 ( 2) 53( 2) 1 54 ( 4) 67(10) H(3) 12( 2) 1 21 ( 2) 68( 3) 56( 9) H(4) 62( 2) 242( 1 ) 209( 3) 35( 8) H(4a) 91 ( 2) 239( 1) 454( 3) 32( 7) H1 (5) -9( 2) 1 45 ( 2) 503( 3) 63(10) H2(5) 44( 2) 85( 1) 438( 3) 36( 7) HI(61) 27( 4) 98( 3) 770( 6) 167(24) 2 Unprimed atoms correspond to molecule A; primed (') atoms correspond to molecule B. 101 Table XXI (continued) H1(61) 27( 4) 98( 3) 770( 6) 1 67 ( 24) H2(61) 1 33 ( 4) 61 ( 2) 834( 6) 1 35 ( 21 ) H3(61) 52( 4) 26( 3) 702( 6) 151 ( 23) H1 (71 ) 337( 3) 84( 2) 850( 4) 95( 15) H2(71) 271 ( 3) 1 15( 2) 937( 4) 87( 14) H3(71) 343( 3) 169( 3) 889( 5) 1 27 ( 19) H1 (8) 278( 2) 235( 2) 634( 3) 72( 1 1 ) H 2(8) 337( 2) 1 65 ( 2) 61 1 ( 3) 73( 1 1 ) H(8a) 230( 2) 220( 1) 381 ( 3) 38( 8) H(0 1 ) 3 306( 6) 1 7( 4) 443( 6) 70< 18) H ( 0 1 ) * • 247( 9) 49( 6) 501 ( 13) 1 63 < 61 ) H(04) -85( 2) 235( 2) 260( 4) 76! 12) H ( T ) -484( 2) 74( 1) -275( 3) 38( 8) H(2' ) -342( 2) 19( 2) -90( 3) 69< 1 1 ) H(3' ) -208( 3) 99( 2) 12( 4) 73< 1 1 ) H(4' ) -283( 2) 226( 1 ) -1 1 0 ( 3) 44 8) H(4a') -306( 2) 238( 1 ) -356( 3) 32 7) H 1(5' ) -1 89 ( 2) 1 65 ( 2) -4 1 2 ( 3) 49 i 9) H 2(5') -222( 2) 90( 1 ) -360( 3) 26 k 7) H1 (61 1 ) -286( 3) 68( 2 ) -750( 4) • 96 114) H 2(61') -200( 3) 60( 2) -609( 5) 1 1 2 (18) H 3 ( 6 1 ' y . -2 1 2 ( 3) 1 30 ( 2) -695( 5) 118 (17) H1 (71 ' ) -437( 3) 1 19( 2) -855( 5) 1 1 7 ( 1 8 ) H 2(71') -51 4( 4) 1 62 ( 3) -823( 6) 145 (27) H3(71') -520( 4) 85( 3) -794< 5) 1 46 (19) H1 (8' ) -493( 2) 2 1 7 ( 2) -546( 3) 59 ( 9) H 2(8') -532( 3) 1 33( 2) -547I 3) 73 (10) H(8a') -443( 2) 1 93 ( 2) -292I 3) 56 ( 8) H(01') -374( 8) 1 3( 6) -400I 12 ) 50 (53) H(01')* -464( 8) 7( 7) -464< 14) 140 (53) H(04') -1 15( 3) 203( 2) -101 5) 107 (15) 3 Hydrogens bonded to 0(1) and 0(1') are i n p o s i t i o n s of 50% occupancy. a A s t e r i s k s (*) denote a d d i t i o n a l hydrogen p o s i t i o n s a r i s i n g from the d i s o r d e r . 1 02 Table XXII F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10 3 A 2) and t h e i r estimated standard d e v i a t i o n s Atom y i 1 y 2 2 y 3 3 2 y, 3 y 2 3 C(1 ) 46( 2) 59( 2) 46( 2) 1 6( 2) 21 ( 2) 1 2( 2) C(2) 65( 3) 61 ( 2) 44( 2) 1 1 ( 2) 24( 2) -7 ( 2) C(3) 49( 2) 67( 2) 30( 2) 7( 2) 12( 2) -6( 2) C(4) 41 ( 2) 47( 2) 34( 2) 6( 2) 12( 1) 4( 2) C(4a) 37( 2) 35( 2) 31 ( 2) 3( 1) 9( 1) 0( 1 ) C(5) 44( 2) 52( 2) 37( 2) -2( 2) 17( 2) -2( 2) C(6) 64( 3) 48( 2) 29( 2) 10( 2) 19( 2) 1 ( 2) C(61 ) 101 ( 4) 83( 3) 50( 3) -5( 3) 39( 3) 15( 2) C(7) 54( 2) 51 ( 2) 35( 2) 1 4( 2) 6( 2) 2( 2) C(71 ) 91 ( ,4) 83( 4) 46( 3) 33( 3) 2( 3) 7( 2) C(8) 41 ( 2) 67( 3) 42( 2) 3( 2) 0( 2) -6( 2) C(8a) 40( 2) 45( 2) 41 ( 2) 0( 2) 1 4( 2) 5( 2) 0(1 ) 95( 2) 63( 2) 57( 2) 39( 2) 30( 2) 1 5( 1 ) 0(4) 41 ( 1) 74( 2) 34( 1) 1 3( 1) 5( 1 ) -6( 1 ) C(1 ' ) 36( 2) 46( 2) 48( 2) -6( 2) 20( 2) -7( 2) C(2' ) 62( 2) 52( 2) 38( 2) -10( 2) 17( 2) 8( 2) C(3' ) 53( 2) 61 ( 2) 31 ( 2) -6( 2) 12( 2) 2( 2) C(4' ) 38( 2) 48( 2) 30( 2) -7 ( 2) 9( 1 ) -7 ( 2) C(4a') 38( 2) 32( 2) 34( 2) -1 ( 1 ) 9( 1) -1 ( 1 ) C(5' ) 37( 2) 46( 2) 32( 2) -6( 2) 10( 2) -3( 2) C(6' ) 53( 2) 45( 2) 30( 2) -1 1 ( 2) 15( 2) -2( 1 ) C(61') 78( 3) 80( 3) 40( 2) -22( 3) 32( 2) -1 6( 2) C(7' ) 52( 2) 48( 2) 29( 2) -14( 2) 2( 2) 3( 1 ) C(71') 84( 3) 95( 4) 38( 3) -32( 3) -5( 3) 3( 2) C(8' ) 39( 2) 50( 2) 52( 2) 1 ( 2) -2( 2) 2( 2) C(8a') 34( 2) 45( 2) 39( 2) 5( 2) 8( 2) -5( 2) 0(1 ' ) 53( 2) 44( 2) 51 ( 2) -4( 1 ) 16( 2) -8( 1 ) 0(4' ) 45( 1) 70( 2) 31 ( 1 ) -14( 1 ) 5( 1 ) -1 ( 1 ) 103 F i g u r e 14 Stereo diagram of a type A molecule of the d i o l (VIII) Di s c u s s i o n The s t r u c t u r e c o n s i s t s of two c r y s t a l l o g r a p h i c a l l y independent molecules, A ( F i g . 14) and B, per asymmetric u n i t hydrogen bonded to each other through 0(4')-H...0(4) i n t e r a c t i o n s . The molecules are r e l a t e d by a pseudo two-fold r o t a t i o n a x i s approximately p a r a l l e l to b and p a s s i n g through the mid-point of 0(4) and 0 ( 4 ' ) . A d d i t i o n a l hydrogen bonds, l i n k i n g n e i g h b o r i n g asymmetric u n i t s , r e s u l t i n a t h r e e - dimensional bonding network ( F i g . 15) thus i n c r e a s i n g the packing energy and r i g i d i t y of the s t r u c t u r e . Each asymmetric 104 u n i t experiences s i x H-bonds. The refinement of four hydrogens (around 0(1) and 0 ( 1 ' ) ) , each with occupancies of 0.5, may be cons t r u e d as the refinement of the oxygen lone p a i r s which would e x p l a i n the short 0 ( 1 ) - H(01)* and OO')-H(OI') bonds of 0.54(11) and 0.63(11) A, r e s p e c t i v e l y (bond lengths and angles are given i n Tables XXIII-XXVI). However, i t i s c h e m i c a l l y and s t r u c t u r a l l y reasonable to assume that hydrogen atoms do l i e i n the v i c i n i t y F i g u r e 15 Stereo packing diagram of the d i o l (VIII) 105 of the r e f i n e d c e n t r o i d s of e l e c t r o n d e n s i t y and on the l i n e s through the oxygens and these adjacent c e n t r o i d s . A l t e r n a t i v e i n t e r p r e t a t i o n s of the g e o m e t r i c a l arrangements of hydrogens around oxygens 0(1) and 0(1') invoke what would appear to be p h y s i c a l l y u n r e a l i s t i c c o n d i t i o n s and can r e s u l t i n decreases i n the extent of hydrogen bonding. Consider the f o l l o w i n g s i t u a t i o n s : i ) hydrogens H(01) and H(01')* assume f u l l occupancy, i i ) hydrogens H(01) and H(01') assume f u l l occupancy, i i i ) hydrogens H(01)* and H(01') assume f u l l occupancy and i v ) H(01)* and H(01')* assume f u l l occupancy. In case ( i ) the space group symmetry r e s u l t s i n a H(01')*(x,y,z)...H(01')*(-x-1,-y,-z- 1) c o n t a c t d i s t a n c e of 1.1 A d e s p i t e otherwise f a v o r a b l e hydrogen bonding geometry between 0(1')(x,y,z) and 0 ( 1 ' ) ( - x - 1 , - y , - z - l ) . From the 0 (1 ) (x , y , z ) -H (01 ) . . .0 (1 ' ) (-x , -y ,-z ) angle- of 159(12)° and H(01)...0(1') d i s t a n c e of 1.87(9) A hydrogen bonding between 0 ( l ) ( x , y , z ) and 0 ( 1 ' ) ( - x , - y , - z ) may be i n f e r r e d ; however, i f indeed the H(01') p o s i t i o n was occupied by a lone p a i r of e l e c t r o n s then t h i s bonding may not. be i n f e r r e d , f o r the 0(1)(x,y,z)-H(01) and 0 ( 1 ' ) ( - x , - y , - z ) - ( l o n e p a i r ) v e c t o r s are p a r a l l e l and separated by approximately 1 A. If i n s t e a d of H(01), the H(01)* p o s i t i o n was f u l l y occupied, as i n case ( i v ) , the same H(01')*...H(01')* c o n t a c t of 1.1 A would occur and furthermore, no hydrogen bonding c o u l d take p l a c e between 0(1) and 0 ( 1 ' ) . Case ( i i ) invokes s i m i l a r l y d r a s t i c c o n d i t i o n s with H(01)(x,y,z) being only 1.1 A from H ( 0 1 ' ) ( - x , - y , - z ) , accompanied by a l o s s of a hydrogen bond between the symmetry r e l a t e d 0(1') atoms at (x,y,z) and (-x-1,-y-1,-z-1). A s s i g n i n g u n i t 106 Table XXIII Bond le n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(1 ) -C(2) 1 .493(4) C O ' ) -C(2') 1 .493(4) C O ) -C(8a) 1 .539(4) C O ' ) -C(8a') 1 .529(4) C O ) -0(1 ) 1 .426(4) C O ' ) -0(1') 1 .428(4) C(2) -C(3) 1 .309(4) C(2' ) -C(3') 1 .316(4) C(3) -C(4) 1 .485(4) C(3' ) -C(4') 1 .491(4) C(4) -C(4a) 1 .519(4) C(4' ) -C(4a') 1 .513(4) C(4) -0(4) 1 .435(3) C(4' ) -0(4'.) 1 .439(3) C(4a) -C(5) 1 .514(4) C(4a') -C(5') 1 .515(4) C(4a) -C(8a) 1 .525(4) C(4a') -C(8a') 1 .536(4) C(5) -C(6) 1 .513(4) C(5' ) -C(6') 1 .507(4) C(6) -C(61) 1 .513(5) C(6' ) -C(61') 1 .504(4) C(6) -C(7) 1 .324(4) C(6' ) -C(7') 1 .323(4) C(7) -C(71) 1 .508(5) C(7' ) -C(71') 1 .513(5) C(7) -C(8) 1 .508(4) C(7' ) -C(8') 1 .504(4) C(8) -C(8a) 1 .523(4) C(8' ) -C(8a') 1 .520(4) 107 Table XXIV Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -CO ) -C(8a) 112 .4(3) C(2' ) -CO ' ) -C(8a) 1 12 .7(3) C(2) -CO) -0(1) 109 .6(3) C(2' ) -CO ' ) -0(1') 1 07 .7(3) C(8a) -CO ) -0(1 ) 1 12 .3(3) C(8a') -CO ' ) -0(1') 1 15 .1(2) C O ) -C(2) -C(3) 124 .3(4) CO') -C(2') -C(3') 123 .6(3) C(2) -C(3) -C(4) 122 .9(3) C(2' ) -C(3') -C(4') 123 .5(3) C(3) -C(4) -C(4a) 1 1 1 .4(3) C(3' ) -C(4') -C(4a) 1 1 1 .8(3) C(3) -C(4) -0(4) 107 .3(3) C(3' ) -C(4') -0(4') 1 1 1 .5(3) C(4a) -C(4) -0(4) 1 1 4 .4(2) C(4a') -C(4') -0(4') 110 .2(2) C(4) -C(4a) -C(5) 1 14 .4(3) C(4' ) -C(4a') -C(5') 1 14 .2(3) C(4) -C(4a) -C(8a) 108 .6(2) C(4' ) -C(4a' ) -C(8a) 108 .8(2) C(5) -C(4a) -C(8a) 1 1 1 .0(2) C(5' ) -C(4a' ) -C(8a) 110 .7(2) C(4a) -C(5) -C(6) 1 14 .2(3) C(4a') -C(5') -C(6') 1 1 4 .0(3) C(5) -C(6) -C(61) 113 .2(4) C(5' ) -C(6') -C(61' ) 1 1 3 .7(3) C(5) -C(6) -C(7) 1 22 .4(3) C(5' ) -C(6') -C(7' ) 122 .5(3) C(61 ) -C(6) -C(7) 1 24 .5(4) C(61') -C(6' ) -C(7' ) 123 .8(3) C(6) -C(7) -C(71) 124 .3(4) C(6' ) -C(7') -C(71')124 .0(4) C(6) -C(7) -C(8) 1 22 .4(3) C(6' ) -C(7' ) -C(8') 122 .3(3) C(71) -C(7) -C(8) 1 13 .3(4) C(71' ) -C(7' ) -C(8') 113 .6(4) C(7) -C(8) -C(8a) 1 14 .0(3) C(7' ) -C(8') -C(8a')114 .5(3) C O ) -C(8a) -C(4a) 1 13 .6(3) CO') -C(8a' ) -C(4a')113 .4(2) C O ) -C(8a) -C(8) 1 12 .7(3) C O ' ) -C(8a' ) -C(8') 1 13 .3(3) C(4a) -C(8a) -C(8) 110 .3(3) C(4a') -C(8a') -C(8') 109 .5(3) 108 Table XXV © Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(1 ) -H(1) 1 . 02(3) C O ' ) -HO ' ) 0 .96(3) C(2) -H(2) 0. 93(3) C(2' ) -H(2') 0 .97(3) C(3) -H(3) 0. 94(3) C(3' ) -H(3') 0 .96(3) C(4) -H(4) 0. 96(2) C(4' ) -H(4') 1 .01(3) C(4a) -H(4a) 0. 96(2) C(4a') -H(4a") 1 .00(2) C(5) -H1(5) 0. 99(3) C(5' ) -H1(5') 0 .92(3) C(5) -H2(5) 1 . 00(3) C(5' ) -H2(5') 1 .02(2) C(61 ) -HI(61) 0. 93(6) C(61') -HI(61') 0 .91(4) C(61 ) -H2(61) 0. 92(5) C(61') -H2(61') 0 .96(4) C(61 ) -H3(61) 0. 95(5) C(61') -H3(61') 0 .90(4) C(71 ) -H1(71) 0. 91 (4) C(71' ) -H1(71 * ) 0 .93(4) C(71 ) -H2(71 ) 0. 94(4) C(71') -H2(71' ) 0 .85(5) C(71 ) -H3(71 ) 1 . 02(4) C(71') -H3(71 ' ) 0 .98(5) C(8) -H1(8) 0. 97(3) C(8' ) -H1 (8' ) 1 .03(3) C(8) -H2(8) 0. 96(3) C(8' ) -H2(8' ) 1 .02(3) C(8a) -H(8a) 0. 93(3) C(8a') -H(8a' ) 1 .03(3) 0( 1 ) -H(01) 0. 93(9) O ( T ) -H(01') 0 .63(11) 0(1") -H(01)* 0. 54(11) 0(1 ' ) -H(01')* 0 .8600) 0(4) -H(04) 0. 90(3) 0(4') -H(04') 0 .94(4) 109 Table XXVI Bond angles i n v o l v i n g hydrogen atoms (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -c( 1) -H(1 ) 109.6( 14) C(2' ) -C(1') -H(1') 110.3( 15) C(8a) -c( 1) -H(1) 107.9( 14) C(8a' )-cd' ) -H(1') 109.3( 14) 0(1) -c( 1) -H(1 ) 104.7( 14) 0(1') -C(1') -H(1') 101.2( 15) C(1 ) -c( 2) -H(2) 116(2) C( 1 ' ) -C(2') -H(2') 115(2) C(3) -c( 2) -H(2) 120(2) C(3' ) -C(2') -H(2') 122(2) C(2) -c( 3) -H(3) 124(2) C(2' ) -C(3') -H(3') 120(2) C(4) -c( 3) -H(3) 113(2) C(4' ) -C(3') -H(3') 116(2) C(3) -c( 4) -H(4) 112.5( 14) C(3' ) -C(4') -H(4') 110.9( 14) C(4a) -c( 4) -H(4) 104.5( 15) C(4a' )-C(4') -H(4') 104.6( 14) 0(4) -C( 4) -H(4) 106.8( 14) 0(4' ) -C(4') -H(4') 107.6( 14) C(4) -c( 4a) -H(4a) 107.6( 14) C(4' ) -C(4a' )-H(4a') 107.9( 13) C(5) -C( 4a) -H(4a) 108.3( 14) C(5' ) -C(4a' )-H(4a') 108.6( 13) C(8a) -C( 4a) -H(4a) 106.6( 14) C(8a' )-C(4a' )-H(4a') 106.3( 13) C(4a) -c( 5) -H1(5) 112(2) C(4a' )-C(5') -H1(5') 110(2) C(4a) -C( 5) -H2(5) 112.6( 14) C(4a' )-C(5') -H2(5') 112.8( 12) C(6) -c< 5) -H1(5) 108(2) C(6' ) -C(5') -H1(5') 107(2) C(6) -c< 5) -H2(5) 107.3( 15) C(6' ) -C(5') -H2(5') 107.6( 13) H1 (5) -CI 5) -H2(5) 102(2) HI (5' )-C(5') -H2(5') 106(2) C(6) -CI 61 ) -H1(6) 112(3) C(6* ) -C(61' )-H1(6') 114(2) C(6) -c< 61 ) -H2(6) 102(3) C(6' ) -C(61' )-H2(6') 109(2) C(6) -c< 61 ) -H3(6) 113(3) C(6' ) -C(61' )-H3(6') 113(3) H1(61 ) -c 61 ) -H2(6) 113(4) H1 (61 ')-C(61 ')-H2(6')103(3) H1(61 ) -c 61 ) -H3(6) 108(4) H1 (61 ')-C(61 ')-H3(6')112(3) H2(61) -c [61 ) -H3(6) 108(4) H2(61 ')"C(61 ')-H3(6')105(4) C(7) -c [71 ) -H1(7) 109(2) C(7' ) -C(71' )"H1(7') 115(3) C(7) -c [71 ) -H2(7) 119(2) C(7' ) -C(71' )-H2(7') 114(4) C(7) -c [71 ) -H3(7) 108(2) C(7' ) -C(71* )-H3(7*) 110(3) H1(71 ) -c [71 ) -H2(7) 108(3) HI (71 ')-C(71 ')-H2(7')106(4 H1 (71 ) -c (71 ) -H3(7) 109(4) H1 (71 ')-C(71 ')-H3(7')108(4 H2(71 ) -c (71 ) -H3(7) 105(3) H2(71 ')~C(71 ')-H3(7')101(4 C(7) -c (8) -H1(8) 109(2) C(7' ) -C(8') -H1(8') 111.6 15) C(7) -c (8) -H2(8) 110(2) C(7' ) -C(8') -H2(8') 1 07(2 C(8a) -c (8) -H1(8) 109(2) C(8a' )-C(8*) -H1(8') 109.9 15) C(8a) -c (8) -H2(8) 108(2) C(8a' )-C(8') -H2(8') 110(2 H1 (8) -c (8) -H2(8) 107(3) H1 (8' )-C(8') -H2(8') 1 03(2 C(1 ) -c (8a) -H(8a) 102.6( 15) C( 1 ' ) -C(8a' )-H(8a') 105.9 15) C(4a) -c (8a) -H(8a) 107.3{ 15) C(4a' )-C(8a' )-H(8a' ) 105.1 (15) C(8) -c (8a) -H(8a) 109.8( 15) C(8' ) -C(8a' )-H(8a') 109(2 C(1) -o (1 ) -H(01) 119(3) C( 1 ' ) -0(1') -H(01') 1 19(3 C(1 ) -0 (1) -H(01) * 120(12) C( 1 ' ) -0(1') -H(01') * 126(9 H(01 ) -o (1) -H(01) *113(13) H(01 ' )-0(1') -H(01') * 107(1 ) C(4) -o (4) -H(04] 110(2) C(4' ) -0(4') -H(04') 106(2 110 occupancies to H(01) and H(01') i s to construe H(01')* as a r e f i n e d lone p a i r and t h i s i m p l i c a t i o n leads to a c l o s e 01'(lone p a i r ) ( x , y , z ) . . . 0 1 ' ( l o n e p a i r ) ( - x - 1 , - y , - z - 1 ) c o n t a c t of 1.1 A - an unstable c o n f i g u r a t i o n . The t h i r d case does not e n t a i l c l o s e atomic c o n t a c t s , however, the number of hydrogen bonds i s reduced as i n ( i i ) . The most f a v o r a b l e i n t e r p r e t a t i o n , a l l u d e d t o e a r l i e r , takes i n t o c o n s i d e r a t i o n a d i s o r d e r e d arrangement of the hydrogens on 0(1) and 0 ( 1 ' ) , namely f r a c t i o n a l occupancy f o r each of the four hydrogens, e f f e c t i n g l i n k a g e of the asymmetric u n i t s v i a bonding between 0(1) and 0(1') by 0 ( 1 ) ( x , y , z ) - H(01)...0(1')(-x,-y,-z)-H(01')*...0(1')(1+x,y,1+z)- H(01')...0(1)(1-x,-y,1-z)-H(01)*. Three important aspects concerning t h i s arrangement are f i r s t l y , that the occupancy of each hydroxyl hydrogen i s r e s t r i c t e d to e x a c t l y 50% — the reader may convince h i m s e l f t h a t any other degree of occupancy would r e s u l t i n p h y s i c a l l y u n r e a l i s t i c H...H c o n t a c t s (vide supra) — secondly, that such an arrangement p r o v i d e s a l i n k between asymmetric u n i t s along the a - d i r e c t i o n 5 and l a s t l y , that the c h a i n l e n g t h i n v o l v i n g t h i s sequence of bonds (.i.e. 0(1)...0(1') type) i s four molecules beginning with and then t e r m i n a t i n g at an 0(1) atom. However, the c h a i n s formed by a combination of 0(1)...0(1') and 0(4)...0(4') l i n k s are i n f i n i t e i n l e n g t h ( F i g . 15 and Table XXVII). The conformation adopted by each molecule c o n s i s t s of a 5 T h i s l i n k a g e i s a l s o accomplished i n case ( i ) at the expense of c l o s e H...H c o n t a c t s ; cases ( i i ) and ( i i i ) do not a f f o r d any l i n k along a. 111 h a l f - c h a i r cyclohexene r i n g c i s - f u s e d to a h a l f - c h a i r c y c l o h e x e n - d i o l moiety. Although the gross molecular conformations are the same f o r both molecules i n the asymmetric u n i t , d e t a i l e d d i f f e r e n c e s are n o t i c e a b l e . D e v i a t i o n s of up to 4.2° are observed i n corresponding (heavy atom) angles i n v o l v i n g Table XXVII Hydrogen bonding geometries Distances are in Angstroms and angles in degrees. 0-H H...0 0-H...0 0(4')(x,y,z)-H...0(4)(x,y,z) 0.94(4) 1.88(4) 176(3) 0(4)(x,y,z)-H...0(4')(x,1/2-y,1/2+z) 0.90(3) 1.93(3) 169(3) 0(l)(x,y,z)-H...0(l')(-x,-y,-z) 0.93(9) 1.87(9) 158(5) 0(l')(x,y,z)-H...0(l)(-x,-y,-z) 0.63(11) 2.16(12) 159(12) 0(l')(x,y,z)-H*...0(l')(-x-l,-y,-z-l) 0.86(10) 1.89(10) 170(12) oxygens in A and B, and may be a t t r i b u t e d to the e f f e c t s of hydrogen bonding. Bond l e n g t h s and other bond angles do not d i f f e r s i g n i f i c a n t l y between molecules. Examination of the t o r s i o n angles (Table XXVIII) i n d i c a t e s f u r t h e r minor c o n f o r m a t i o n a l d i f f e r e n c e s . The OH c o n f i g u r a t i o n s i n each molecule are both a n t i with res p e c t to the bridgehead hydrogens. T h i s confirms the expected major isomer formed by the r e d u c t i o n of the 1,4-dione by NaBH,, the method by which the present compound was prepared. 112 D e s p i t e the f a v o r a b l e geometry f o r a hydrogen a b s t r a c t i o n r e a c t i o n i n v o l v i n g the upper hydrogen on C(5) ( F i g . 14), and the C(3) atom, such a r e a c t i o n does not proceed p h o t o c h e m i c a l l y (at >350 nm) due to the lack of a s u i t a b l e chromophore. Bonds j o i n i n g atoms C(1), C(2), C(3), C(4), C(4a) and C(5), and s i m i l a r l y C ( D , C(2'), C ( 3 ' ) , C ( 4 ' ) , C(4a') and C(5') are a l l sh o r t e r than accepted v a l u e s . T h i s may be due to s l i g h t h y b r i d i z a t i o n d e v i a t i o n s from the formal s p 3 and s p 2 s t a t e s . The l a r g e r than normal e n d o c y c l i c bond angles at these c e n t e r s are c o n s i s t e n t w i t h t h i s r a t i o n a l e . Comparison with Tetrahydronaphthoquin-4c-ols The present molecular conformations are s i m i l a r to the l e a s t energy conformations p r e d i c t e d by Bucourt and Hainaut (38) and found i n p r e v i o u s l y s t u d i e d naphthoquinols (Chapters I - I I I and r e f e r e n c e 32). Many of the s t r u c t u r a l trends noted i n these past s t u d i e s are a l s o observed i n the c u r r e n t d i o l compound. Not u n l i k e the other naphthoquinols, the c i s - f u s e d r i n g s i n the d i o l molecules, so j o i n e d , form three approximate planes — two planes d e f i n e d by each of the double bonds (C(1), C(2), C(3), C(4) and C(5), C ( 6 ) , C(7), C(8)) are almost p e r p e n d i c u l a r to each other (with a d i h e d r a l angle of 96°) and each of these planes subtends an angle of approximately 141° with respect to the t h i r d plane c o n t a i n i n g atoms C(4)-C(4a)-C(8a)-C(8) (and s i m i l a r l y C ( 4 ' ) - C(4a')-C(8a')-C(8') i n the other m o l e c u l e ) . Since the molecules i n the asymmetric u n i t are very s i m i l a r , s t r u c t u r a l f e a t u r e s and valu e s f o r B molecules w i l l be Table XXVIII T o r s i o n angles (deg) with estimated standard d e v i a t i o n s i n parentheses Atoms Value c( 8a) -c( 1) -c( 2) -c( 3) -3.1 ( 4) 0( 1) -c( 1) -c( 2) -c( 3) 122.5( 4) c( 2) -c( 1) -c( 8a) -c( 4a) 32. 1 ( 4) c( 2) -c( 1) -c( 8a) -c( 8) 158.5( 3) o( 1) -c( 1) -C( 8a) -c( 4a) -92.0( 3) o( 1) -c( 1) -c( 8a) -c( 8) 34.4( 4) c( 1) -c( 2) -c( 3) -c( 4) 0.4( 5) c( 2) -c( 3) -c( 4) -c( 4a) -26.5( 4) c( 2) -c( 3) -c( 4) -0( 4) -152.41 3) c( 3) -c( 4) -c( 4a) -C( 5) -71.81 4) c< 3) -c( 4) -CI 4a) -c( 8a) 52.81 4) 0( 4) -c( 4) -C( 4a) -c( 5) 50.01 4) 0( 4) -c( 4) -C( 4a) -CI 8a) 174.71 3) c( 4) -c( 4a) -CI 5) -CI 6) 166.41 3) c( 8a) -c( 4a) -c< 5) -CI 6) 43.01 4) C( 4) -c( 4a) -CI 8a) -CI 1 ) -57.21 3) C( 4) -c( 4a) -CI 8a) -CI 8) 175. 1 3) C( 5) -CI 4a) -CI 8a) -CI 1) 69.4 ,3) c< 5) -C( 4a) -CI 8a) -CI 8) -58.2 (4) c< 4a) -CI 5) -c 6) -c 61 ) 166.4 (3) C( 4a) -CI 5) -c 6) -c ,7) -14.2 (4) CI 5) -c< 6) -c '7) -c (71 ) -179.3 (3) CI 5) -c< 6) -c [7) -c (8) 0.2 (5) c 61 ) -CI 6) -c (7) -c (71 ) 0.0 (5) c 61) -c ,6) -c (7) -c (8) 179.5 (4) c t6) -c [7) -c (8) -c (8a) -16.0 (5) c [71 ) -c [7) -c (8) -c (8a) 1 63.5 (3) c (7) -c [8) -c (8a) -c (1) -83.7 (4) c [7) -c (8) -c (8a) -c (4a) 44.5 (4) c [8a' ) -c ( T ) -c (2' ) -c (3' ) -7.6 (4) 0 (1 ' ) -c [ 1 ' ) -c (2' ) -c (3' ) 120.5 (4) c (2' ) -c ( 1 ' ) -c (8a' ) -c (4a' ) 35.7 (3) c (2* ) -c ( 1 ' ) -c (8a' ) -c (8' ) 161.3 (3) 0 (1 ' ) -c ( 1 ' ) -c (8a' ) -c (4a' ) -88.3 (4) 0 (1 ' ) -c ( 1 ' ) -c (8a' ) -c (8' ) 37.3 (4) c (1 ' ) -c (2' ) -c (3' ) -c (4' ) 2.3 (5) c (2' ) -c (3' ) -c (4' ) -c (4a' ) -25.0 (4) c (2' ) -c (3' ) -c (4' ) -o (4' ) -148.8 (3) c (3' ) -c (4' ) -c (4a' ) -c (5' ) -73.7 (3) c (3' ) -c (4' ) -c (4a' ) -c (8a' ) 50.6 (3) 0 (4' ) -c (4' ) -c (4a' ) -c (5' ) 50.9 (3) 0 (4' ) -c (4' ) -c (4a' ) -c (8a' ) 175. 1 (2) c (4' ) -c (4a' ) -c (5' ) -c (6' ) 167. 1 (3) c (8a' ) -c (4a* ) -c (5' ) -c (6' ) 43.9 (3) c (4* ) -c (4a' ) -c (8a* ) -c (1 ' ) -57.8 (3) c (4' ) -c (4a' ) -c (8a' ) -c (8' ) 174.6 (3) 1 1 4 Table XXVIII (continued) C(5' ) -C(4a') -C(8a') - c ( D 68. 5(3) C(5' ) -C(4a') -C(8a') -C(8') -59. 1(3) C(4a') -C(5') -C(6') -C(61') 167. 6(3) C(4a') -C(5') -C(6') -C(7') -13. 2(4) C(5' ) -C(6') -C(7') -C(71') 177. 7(4) C(5' ) -C(6') -C(7') -C(8*) -2. 6(5) C(61' ) -C(6') -C(7') - C ( 7 T ) -3. 1(5) C(61') -C(6') -C(7') -C(8*) 176. 5(3) C(6' ) -C(7') -C(8') -C(8a') -13. 9(5) C(71') -C(7') -C(8') -C(8a') 165. 8(3) C(7' ) -C(8') -C(8a') - C ( T ) -83. 7(4) C(7' ) -C(8') -C(8a') -C(4a') 44. 0(4) C(8a) -C(1 ) -C(2) -H(2) -179(2) 0(1) -C(1 ) -C(2) -H(2) -53(2) H(1 ) -C(1) -C(2) -C(3) -123.0(15) H(1 ) -C(1 ) -C(2) -H(2) 61(3) C(2) -CO) -C(8a) -H(8a) -83(2) 0(1 ) -CO ) -C(8a) -H(8a) 152.5(15) H(1) -CO) -C(8a) -C(4a) 153.2(15) H(1 ) -CO ) -C(8a) -C(8) -80(2) H(1 ) -CO ) -C(8a) -H(8a) 38(2) C(2) -CO ) -0(1) -H(01) 94(4) C(2) -CO ) -0(1 ) -H(01)* -115(15) C(8a) -CO) -0(1) -H(01) -140(4) C(8aY - -CO) -0(1 ) -H(01)* 10(15) H(1 ) - c o ) -0(1 ) -H(01) -23(4) H(1 ) -CO) -0(1 ) -H(01)* 127(15) C(1 ) -C(2) -C(3) -H(3) -179(2) H(2) -C(2) -C(3) -C(4) 176(2) H(2) -C(2) -C(3) -H(3) -3(3) C(2) -C(3) -C(4) -H(4) 91(2) H(3) -C(3) -C(4) -C(4a) 153(2) H(3) -C(3) -C(4) -0(4) 27(2) H(3) -C(3) -C(4) -H(4) -90(2) C(3) -C(4) -C(4a) -H(4a) 167.9(15) 0(4) -C(4) -C(4a) -H(4a) -70.3(15) H(4) -C(4) -C(4a) -C(5) 166.4(14) H(4) -C(4) -C(4a) -C(8a) -68.9(15) H(4) -C(4) -C(4a) -H(4a) 46(2) C(3) -C(4) -0(4) -H(04) 173(2) C(4a) -C(4) -0(4) -H(04) 49(2) H(4) -C(4) -0(4) -H(04) -66(3) C(4) -C(4a) -C(5) -H1(5) -70(2) C(4) -C(4a) -C(5) -H2(5) 44(2) C(8a) -C(4a) -C(5) -H1(5) 166(2) C(8a) -C(4a) -C(5) -H2(5) -80(2) H(4a) -C(4a) -C(5) -C(6) -73.7(15) H(4a) -C(4a) -C(5) -H1(5) 50(2) H(4a) -C(4a) -C(5) -H2(5) 164(2) C(4) -C(4a) -C(8a) -H(8a) 56(2) C(5) -C(4a) -C(8a) -H(8a) -178(2) 1 15 Table XXVIII (continued) H ( 4 a ) -c( 4a) -c( 8a) - c ( D -172.9(15) H(4a) -c( 4a) -c( 8a) -C(8) 59.5(15) H ( 4 a ) -c( 4a) -c( 8a) -H(8a) -60(2) H1 (5) -c( 5) -c( 6) -C(61) 41 (2) H1 (5) -c( 5) -c( 6) -C(7) -140(2) H2(5) -c( 5) -c( 6) -C(61) -68.1(14) H2(5) -c( 5) -c( 6) -C(7) 111.4(14) C(5) -c< 6) -c( 61 ) -H1(61 ) -66(4) C(5) -C( 6) -c( 61 ) -H2(61 ) 173(3) C(5) -C( 6) -c( 61 ) -H3(61) 57(3) C(7) -C( 6) -CI 61 ) -H1(61) 1 14(4) C(7) -CI 6) -c( 61 ) -H2(61 ) -7(3) C(7) -CI 6) -c( 61 ) -H3(61 ) -123(3) C(6) -CI 7) -C( 71 ) -H1(71 ) 98(3) C(6) -C! 7) -CI 71 ) -H2(71 ) -25(3) C(6) -CI 7) -CI 71 ) -H3(71 ) -144(3) C(8) -CI 7) -CI 71 ) -H1(71 ) -81(3) C(8) -CI 7) -c< 71 ) -H2(71) 155(3) C(8) -CI 7) -c< 71 ) -H3(71 ) 36(3) C(6) -CI 7) -CI 8) -H1(8) 106(2) C(6) -CI 7) -CI 8) -H2(8) -137(2) C(71 ) -c< ,7) -c< 8) -H1(8) -74(2) C(71 ) -c ,7) -CI 8) -H2 (8) 42(2) C(7) -c 8) -CI 8a) -H(8a) 163(2) H1 (8) -c [8 ) -CI 8a) -CO) 154(2) H1 (8) -c (8) -CI 8a) -C(4a) -78(2) H1 (8) -c [8) -CI 8a) -H(8a) 40(3) H2(8) -c [8) -CI 8a) -CO) 38(2) H2(8) -c (8) -CI ,8a) - C ( 4 a ) 167(2) H2(8) -c (8) -CI ,8a) -H(8a) -75(2) C(8a') -c (1 ' ) -c [2' ) -H(2*) 176(2) 0(1 ' ) -c ( 1 ' ) -c [2' ) -H(2') -56(2) H(1 ' ) -c i 1') -c (2' ) -C(3') -130.005) H(1 ' ) -c 11') -c [2* ) -H(2') 54(2) C(2' ) -c ( r ) -c (8a' ) -H(8a') -79(2) 0(1 ' ) -c ( 1 1 ) -c (8a' ) -H(8a') 157(2) H(1 ' ) -c ( 1 ' ) -c (8a' ) -C(4a') 159(2) H(1 ' ) -c ( 1 ' ) -c (8a' ) -C(8') -76(2) H(1 ' ) -c ( 1 ' ) -c (8a' ) -H(8a') 44(2) C(2' ) -c ( 1 ' ) -o (1 ' ) -H(01') -57(1 1 ) C(2' ) -c ( 1 ' ) -o (1 ' ) -H(01') * 158(11 ) C(8a') -c ( 1 ' ) -o (1 ' ) -H(01') 68(1 1 ) C ( 8 a * ) -c 0') -o (1 ' ) -H(01') * - 7 4 d 1 ) H( r ) -c ( i ' ) -o 1 ' ) -H(01') -173(11) H( 1 ' ) -c ( i ' ) -o (1 ' ) -H(01') * 43(11) c( r ) -c (2' ) -c (3' ) -H(3') -173(2) H(2' ) -c (2' ) -c (3' ) -C(4*) 178(2) H(2' ) -c (2' ) -c (3' ) -H(3') 3(3) C(2' ) -c (3' ) -c (4' ) -H(4') 91.3(15) H(3' ) -c (3' ) -c (4' ) -C(4a') 150(2) H(3' ) -c (3' ) -c (4' ) -0(4') 26(2) H(3' ) -c (3' ) -c (4' ) -H(4') -93(3) 1 16 Table XXVIII (continued) C(3' ) -c( 4' ) -C(4a') -H(4a') 165.4( 13) 0(4' ) -c( 4' ) -C(4a') -H(4a') -70.0( 13) H(4' ) -c( 4' ) -C(4a') -C(5') 166.3( 14) H(4' ) -c( 4' ) -C(4a') -C(8a') -69.5( 14) H(4' ) -c( 4' ) -C(4a') -H(4a') 45(2) C(3' ) -c( 4' ) -0(4') -H(04') -54(2) C(4a' ) -c( 4' ) -0(4') -H(04') -179(2) H(4' ) -c( 4' ) -0(4') -H(04') 68(3) C(4' ) -c( 4a' ) -C(5' ) -H1(5') -73(2) C(4' ) -c( 4a' ] -C(5') -H2(5') 44.0( 14) C(8a' ) -c( 4a' ) -C(5') -H1(5') 164(2) C(8a' ) -c< 4a' ] -C(5' ) -H2(5') -79. 1( 14) H(4a' ) -c( 4a' -C(5') -C(6') -72.4( 14) H(4a' ) -c< 4a' ' -C(5') -H1(5') 47(2) H(4a' ) -c< 4a' > ~C(5') -H2(5') 165(2) C(4' ) -C( 4a' 1 -C(8a') -H(8a') 57(2) C(5' ) -c< 4a' ) -C(8a' ) -H(8a') -176(2) H(4a' ) -CI 4a' ) -C(8a' ) -CO ' ) - 173.7( 13) H(4a' ) -c< 4a' } -C(8a') -C(8') 58.7( 14) H(4a' ) -c< 4a' ) -C(8a' ) -H(8a') -58(2) H1 (5' ) -c< 5' ) -C(6') -C(61') 46(2) H1 (5' ) -c 5' ) -C(6') -C(7') -134(2) H2(5' ) -c ,5' ) -C(6') -C(61') -66.51 13) H2(5' ) -c [5' ) -C(6' ) -C(7') 112.71 13) C(5' ) -c (6* ) -C(61') -H1(61'] 154(2) C(5' ) -c (6' ) -C(61' ) -H2(61'] 40(3) C(5* ) -c (6' ) -C(61' ) -H3(61'] -76(3] C(7' ) -c (6' ) -C(61' ) -HI(61•; -25(3] C(7' ) -c (6' ) -C(61') -H2(61' 1 1-140(3] c(7'; -c (6' ) -C(61') -H3(61' ) 105(3' C(6' ] -c (7' ) -C(71' ) -H1(71' I -11(3 C(6' ] -c (7' ) -C(71' ) -H2(71' 1-134(4 C(6' 1 -c (7' ) -C(71') -H3(71' > 112(3 C(8' -c (7' ) -C(71' ) -H1(71' ) 170(3 C(8' -c (7' ) -C(71' ) -H2(71' ) 46(4 C(8' -c (7' ) -C(71' ) -H3(71' ) -68(3 C(6' -c (7' ) -C(8') -H1(8' ) 112(2 C(6' -c (7' ) -C(8' ) -H2(8') -136(2 C(71 ) -c (7' ) -C(8' ) -H1(8' ) -68(2 C(71 ) -c (7' ) -C(8' ) -H2(8' ) 43(2 C(7' -c (8' ) -C(8a' ) -H(8a' ) 158.5 : 15) HI (8 ) -c (8' ) -C(8a') -CO ' ) 150(2 H1 (8 ) -c (8' ) -C(8a') -C(4a') -83(2 H1 (8 ) -c (8' ) -C(8a') -H(8a') 32(2 H2(8 ) -c (8' ) -C(8a') -CO ' ) 37(2 H2(8 ) -c (8' ) -C(8a') -C(4a') 164(2 H2(8 ) -c (8' ) -C(8a') -H(8a') -81(2 1 17 recorded i n b r a c k e t s f o l l o w i n g the c o r r e s p o n d i n g q u a n t i t i e s f o r the A molecules. Ring t w i s t , which i s s t r i c t l y d e f i n e d as the H(4a)-C(4a)- C(8a)-H(8a) t o r s i o n angle (-60(3)°) [-58(2)°] i s a l s o d e s c r i b e d to a good approximation by the more a c c u r a t e l y determined C ( 1 ) - C(8a)-C(4a)-C(5) t o r s i o n angle of 69.4(3)° [68.5(3)°]. The l a t t e r t o r s i o n angles are s l i g h t l y l a r g e r i n the present s t r u c t u r e s than i n any other 4c-naphthoquinol s t u d i e d i n the s e r i e s and appear to be due to s t e r i c i n t e r a c t i o n s between 0(1) and carbons C(2), C(8), C(8a) and C ( 7 ) . Short c o n t a c t s ( l e s s than the van der Waals r a d i i sum f o r 0 and C of 3.22 A) between these atoms r e s u l t i n these four carbons tending to f o r c e the e x o c y c l i c oxygen i n t o a more s t e r i c a l l y f a v o r e d p o s i t i o n , i_.e. one which minimizes crowding. The p r e s s u r e exerted by C(8a), C(8) and C(7) i s g r e a t e r than, and opposed by, that e x e r t e d by C(2) r e s u l t i n g i n a s l i g h t i n c r e a s e i n the t w i s t angle C(1)-C(8a)-C(4a)-C(5). The C(6)=C(7) bond l e n g t h of 1.324(4) A [1.323(4) A] i s not s i g n i f i c a n t l y longer than that i n s i m i l a r l y s u b s t i t u t e d tetrahydro-1-naphthoquin-4c-ol d e r i v a t i v e s (Chapter III and r e f e r e n c e 32). The i n c r e a s e d e n d o c y c l i c angles around C(6) and C(7) i n the present s t r u c t u r e f o l l o w the p r e v i o u s l y noted trend of i n t e r n a l angle enlargement accompanying i n c r e a s e d s u b s t i t u t i o n at these c e n t e r s . The C(5)-C(6) and C(?)-C(8) bonds are longer i n the d i o l than i n the u n s u b s t i t u t e d t e t r a h y d r o n a p h t h o q u i n o l , as expected on the b a s i s of previous trends observed i n the naphthoquinols with methyl s u b s t i t u e n t s at C(6) and C ( 7 ) . 118 Asymmetric U n i t S i z e - S t r u c t u r e Comparison The obvious d i f f e r e n c e between the d i o l (VIII) and other tetrahydronaphthoquin-4a-ols s t u d i e d i s the presence of a hydroxyl group i n p l a c e of a c a r b o n y l oxygen bonded to C ( 1 ) . The a d d i t i o n a l mode for hydrogen bonding i s probably a f a c t o r i n determining the s i z e of the asymmetric u n i t by p e r m i t t i n g molecules to a s s o c i a t e i n p a i r s while a l l o w i n g H-bonding to adjacent u n i t s v i a the other hydroxyl group, thus e n a b l i n g e f f i c i e n t packing i n the c r y s t a l — the packing c o e f f i c i e n t i s about 0.67 f o r t h i s s t r u c t u r e . S i m i l a r s i t u a t i o n s are found, f o r example, i n hydroxyimino(N,N'-dimethyl)malonamide (41) and (±)- cis-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz(a)anthracene (42) where molecular a s s o c i a t i o n through hydrogen bonding seems to account f o r the presence of two molecules i n the asymmetric u n i t . Conversely, the l i t e r a t u r e shows many examples where m u l t i p l e modes of hydrogen bonding e x i s t but only one molecule i s accomodated i n the asymmetric u n i t . The many i n t e r r e l a t e d f a c t o r s (such as the geometric shape of the molecule, the type of atoms i n v o l v e d , e l e c t r o n i c and s t e r i c e f f e c t s , e t c.) i n v o l v e d i n the growth of the c r y s t a l make i t d i f f i c u l t to p r e d i c t the s i z e of the asymmetric u n i t . Although hydrogen bonding undoubtedly c o n t r i b u t e s to the a s s o c i a t i v e i n t e r a c t i o n i n the present case, i t i s not n e c e s s a r i l y the only reason f o r the i n c r e a s e d number of molecules i n the asymmetric u n i t . As an i l l u s t r a t i o n of t h i s p o i n t , i t i s i n t e r e s t i n g to compare two compounds whose parent r i n g s t r u c t u r e s and conformations are e s s e n t i a l l y the same as 119 the d i o l , namely cis-4a,5,8,8a-tetrahydro-1,4-naphthoquinone (43) and 5a,8o-dimethyl-4ap,5,8,8ap-tetrahydro-1-naphthoquin-4a- o l (44). Both s t r u c t u r e s c r y s t a l l i z e i n m o n o c l i n i c space groups - the former i n P2,/c with Z = 8 and the l a t t e r i n P2,/n with Z = 8. In sharp c o n t r a s t with the present s t r u c t u r e , the naphthoquinone molecule l a c k s any f a c i l i t y f o r hydrogen bonding and t h e r e f o r e an a l t e r n a t i v e e x p l a n a t i o n f o r the g r e a t e r than expected number of molecules i n the asymmetric u n i t must be sought, but i s beyond the scope of t h i s d i s c u s s i o n . The 5a,8a- dimethylnaphthoquinol, on the other hand, d e s p i t e i t s a b i l i t y to hydrogen bond, does so only between symmetry r e l a t e d molecules and not between A and B molecules i n the asymmetric u n i t . 120 PART II CHAPTER V TWISTANE DERIVATIVE (TWISTENONE) 1 22 I n t r o d u c t i o n The s o l u t i o n photochemistry of (I) ( F i g u r e 16) has been r e c e n t l y r e i n v e s t i g a t e d by S c h e f f e r and Walsh (35). I t was found that a s l i g h t m o d i f i c a t i o n i n the method of p h o t o l y s i s had a marked e f f e c t on the r a t i o s of the photoproducts formed. The m o d i f i c a t i o n , which i n v o l v e d i r r a d i a t i n g i n t e r n a l l y r a t h e r than e x t e r n a l l y 1 as p r e v i o u s l y done (25) gave r i s e to ( I I ) and ( I I I ) and an a d d i t i o n a l photoproduct at the expense of ( I I ) . In the o r i g i n a l i n v e s t i g a t i o n , S c h e f f e r et a l . (24,25) had not observed t h i s a d d i t i o n a l product, though i t may have been present i n t r a c e amounts. A c r y s t a l l o g r a p h i c study was c a r r i e d out on t h i s unknown photoproduct i n an attempt to e l u c i d a t e i t s molecular s t r u c t u r e . I t was hoped that the s t r u c t u r a l s o l u t i o n would a i d i n the d e r i v a t i o n of a mechanism f o r the r e a c t i o n . Although i n f r a r e d and NMR techniques were a v a i l a b l e , n e i t h e r a f f o r d e d a r e a d i l y i n t e r p r e t a b l e spectrum and f o r t h i s reason the methods of X-ray c r y s t a l s t r u c t u r e a n a l y s i s were e x p l o i t e d . The s t r u c t u r e "is now shown to be ( I V ) 2 . 1 I n t e r n a l i r r a d i a t i o n i s performed by i n s e r t i n g the lamp i n t o the hollow of the immersion w e l l r e a c t o r v e s s e l ; e x t e r n a l i r r a d i a t i o n i s c a r r i e d out by p l a c i n g the lamp by the e x t e r i o r w a l l of the r e a c t o r v e s s e l . 2 IUPAC name: t r i c y c l o [ 4 . 4 . 0 . 0 3 - 8 ]dec-9-ene-2,5-dione. 1 23 S c h e f f e r and Walsh (1981) (35). S c h e f f e r , Bhandari, Gayler and Wostradowski (1974) (24). F i g u r e 16 Reaction schemes i l l u s t r a t i n g the d i f f e r e n t r e s u l t s from i n t e r n a l (top) and e x t e r n a l (bottom) i r r a d i a t i o n . 124 Experimental Thin c r y s t a l s were ob t a i n e d by slow e v a p o r a t i o n of a hexane/acetone s o l u t i o n . X-ray data were measured with a c r y s t a l of dimensions 0.2 x 0.3 x 0.3 mm3 under the f o l l o w i n g c o n d i t i o n s : g r a p h i t e monochromatized MoKo r a d i a t i o n ; a t h e t a range from 0.0 to 27.5 degrees; an omega scan angle given by (0.80 + 0.35tan©) degrees; a v a r i a b l e h o r i z o n t a l a perture width ( v a r i a t i o n a c c o r d i n g to the e x p r e s s i o n (2.00 + tane) mm); an o- 2(4/6)© scan type; and scan speeds i n the the range 1.34-10.06 deg min" 1. I n t e n s i t y and o r i e n t a t i o n c o n t r o l s were monitored r e g u l a r l y throughout data c o l l e c t i o n . Accurate c e l l parameters were obtained by l e a s t squares f i t to the observed sin© val u e s f o r 21 centered r e f l e c t i o n s . C r y s t a l d ata: C 1 0 H 1 0 0 2 , MW = 162.19, m o n o c l i n i c a = 6.381(2), b = 19.454(2), c = 6.708(2) A, p = 106.24(1)°, V = 799.5(3) A 3, Z = 4, D c = 1.347 g cm" 3, p(MoKo) = 0.870 cm" 1, X = 0.71073 A, space group P2,/n , from absences and s t r u c t u r e a n a l y s i s . I n t e n s i t i e s were c o r r e c t e d f o r Lorentz and p o l a r i z a t i o n e f f e c t s but not f o r a b s o r p t i o n . The decay of the three standards' i n t e n s i t i e s - (253) 1.93%; (T3T), 5.85%; (?62), 4.15% — n e c e s s i t a t e d the a p p l i c a t i o n of a decay c o r r e c t i o n . Of the 1828 unique r e f l e c t i o n s , 930 (50.8%) had I > 3«(I) where * 2 ( l ) = S + 2B + (0.04(S - B ) ) 2 , S being the scan count and B the time- averaged background. 125 S o l u t i o n and Refinement A c u r s o r y a n a l y s i s of the data showed r e f l e c t i o n s of the types hOl, h + 1 = odd and OkO, k = odd were the only r e f l e c t i o n s c l a s s i f i e d as unobserved s y s t e m a t i c a l l y ; t h i s suggested P2,/n symmetry. The i n t e n s i t y s t a t i s t i c s tended more toward a c e n t r i c d i s t r i b u t i o n than an a c e n t r i c one — c o n s i s t e n t with the suggested space group. The s t r u c t u r e was s o l v e d by MULTAN employing 3296 I 2 - r e l a t i o n s h i p s which i n v o l v e d 248 normalized s t r u c t u r e f a c t o r s . The s t a r t i n g set of phases was made up of e i g h t r e f l e c t i o n s : three o r i g i n d e f i n i n g r e f l e c t i o n s , chosen i n accordance with space group r e s t r i c t i o n s and given phases of 0; one r e f l e c t i o n whose phase was determined by the 1,-formula; and four other g e n e r a l r e f l e c t i o n s , prominent i n the I 2 - l i s t i n g and i n i t i a l l y a s s i g n e d phases of 0. Fourteen permutations of the two phases, 0 and ir, among the four general r e f l e c t i o n s r e s u l t e d i n one o u t s t a n d i n g phase s e t . A F o u r i e r s y n t h e s i s , c a l c u l a t e d with t h i s set of phases, produced a map on which the top twelve peaks corresponded to the non-hydrogen atom p o s i t i o n s . Refinement was i n i t i a t e d i n the space group P2,/n (which was confirmed by subsequent refinement as the c o r r e c t space group). In the e a r l y stages of refinement carbon and oxygen atoms were assigned i s o t r o p i c temperature f a c t o r s but l a t e r were converted to a n i s o t r o p i c f o r f u r t h e r c y c l i n g . Hydrogen atoms were e a s i l y i d e n t i f i e d on a d i f f e r e n c e - F o u r i e r map and were subsequently i n c l u d e d i n the f u l l matrix l e a s t squares refinement. Those r e f l e c t i o n s f o r which I < 3c(I) were excluded 126 from the refinement. Convergence was reached at R = 0.037, Rw = 0.043 f o r 149 v a r i a b l e s and 930 r e f l e c t i o n s . Mean and maximum parameter s h i f t s were 0.019 and 0.170*, r e s p e c t i v e l y . The standard d e v i a t i o n i n an o b s e r v a t i o n of u n i t weight was 1.844. A weighting a n a l y s i s confirmed the s u i t a b i l i t y of the chosen weights, w = l/<r 2(F), where * 2 ( F ) i s d e r i v e d from the p r e v i o u s l y d e f i n e d « 2 ( I ) . F l u c t u a t i o n s of ±0.17 e/A 3 on the f i n a l d i f f e r e n c e map appeared to be random. Atomic c o o r d i n a t e s and temperature f a c t o r s are given i n Table XXIX. A n i s o t r o p i c thermal parameters f o r non-hydrogen atoms are l i s t e d i n Table XXX. Di s c u s s i o n The s t r u c t u r e was found to be a twistane (31) d e r i v a t i v e , unsaturated at C(9) and C(10), and having c a r b o n y l s u b s t i t u e n t s at p o s i t i o n s 2 and 5. T h i s appears to be the f i r s t example of an X-ray c r y s t a l s t r u c t u r e d e t e r m i n a t i o n of an unsaturated twistane d e r i v a t i v e and t h e r e f o r e , s t r u c t u r a l comparisons are l i m i t e d to the r e l a t i v e l y few twistanes whose c r y s t a l s t r u c t u r e s are known. G e n e r a l l y , bond lengths are comparable to accepted values (33) with the exception of C(9)=C(10) (1.310(4) A) and the b r i d g i n g bonds, C(3)-C(8) (1.559(3) A) and C(1)-C(6) (1.574(3) A) (Table XXXI). However, the lengthening of the l a t t e r two bonds i s not unusual f o r t h i s type of system; s i m i l a r l engthening of C ( s p 3 ) - C ( s p 3 ) bonds has been r e p o r t e d f o r bridged r i n g hydrocarbons (see f o r example, r e f e r e n c e s 45 and 46). Atom C(2) d e v i a t e s by 0.0083(19) A from the mean plane through C(1), C ( 2 ) , C(3) and 0(2) (Table XXXII); the other 127 Table XXIX F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10 5, H x 10') and i s o t r o p i c thermal parameters (U x 10 3 A 2) with estimated standard d e v i a t i o n s i n parentheses Atom x y_ z Ueq/Uiso C(1) 43183(30) 9198(11) 73230(32) 42 C(2) 46946(32) 16445(10) 81296(30) 43 C(3) 68270(35) 18800(11 ) 78540(33) 50 C(4) 84231(40) 15878(13) 98328(40) 55 C(5) 79127(29) 8327(11 ) 99726(31 ) 43 C(6) 66087(30) 5539(10) 79168(29) 40 C(7) 78841(39) 1 . 7886(12) 64120(37) 51 C(8) 71086(37) 15293(13) 58557(36) 55 C(9) 49048(43) 14393(14) 43397(36) 62 C(10) 35198(41) 10864(12) 50506(36) 56 0(2) 34914(28) 19664( 9) 89031(27) 70 0(5) 85239(26) 5020( 9) 115598(24) 67 H(1 ) 3304(37) 696(11) 7830(32) 53( 6) H(3) 6943(38) 2367(14) 7803(36) 68( 7) H1 (4) 8257(47) 1812(14) 1 1038(47) 84( 9) H2(4) 9855(43) 1611(11) 9740(34) 59( 6) H(6) 6439(32) 82(13) 7943(31) 52( 6) H1 (7) 7583(39) 488(13) 5098(41) 75( 7) H2(7) 9442(38) 766(10) 7115(34) 58( 6) H(8) 8141(38) 1794(13) 5341(35) 67( 7) H(9) 4646(47) 1596(15) 3003(48) 91 ( 9) H( 10) 2038(40) 995(12) 4290(37) 68( 7) 128 Table XXX c F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10* A 2) and t h e i r estimated standard d e v i a t i o n s Atom y,, U22 y 3 3 Hi 2 y, 3 u2 3 C O ) 324(10) 437( 12) 483( 12) -57( 9) 1 04 ( 9) -24( 10) C(2) 434(11) 437( 12) 405( 11) 77( 9) 105( 8) -6( 9) C(3) 552(13) 298( 12) 628( 15) -70( 10) 1 38 ( 1 1 ) 18( 10) C(4) 437(13) 567( 15) 589( 14) - 1 1 8 ( 10) 66( 10) -79( 12) C(5) 364(10) 496( 13) 429( 12) 39( 9) 1 1 4( 8) 48( 10) C(6) 433(11) 296( 1 1 ) 449( 1 1 ) 15( 8) 98( 9) 27( 9) C(7) 481(13) 637( 15) 456( 12) 1 68 ( 1 1 ) 1 87 ( 10) 65( 12) C(8) 56804) 553( 14) 599( 14) 35( 1 1 ) 292( 11) 1 97 ( 12) C(9) 758(16) 684( 16) 385( 12) 301 ( 13) 1 1 4( 12) 1 19( 12) COO) 483(13) 604( 15) 489( 13) 1 38 ( 1 1 ) -17( 11) -1 02 ( 11) 0(2) 691(10) 7 1 7 ( 12) 766( 1 1 ) 205( 9) 306( 9) -146( 9) 0(5) 7150 1) 786( 1 1 ) 456( 9) 81 ( 8) 67( 8) 1 79 ( 9) 129 Table XXXI Bond lengths (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(1 ) -C(2) 1 .505(3) C(5) -C(6) 1.499(3) C O ) -COO) 1.501(3) C(5) -0(5) 1.211(2) C(2) -C(3) 1.495(3) C(6) -C(7) 1 .533(3) C(2) -0(2) 1.214(2) C(6) -CO ) 1.573(3) C(3) -C(4) 1.538(3) C(7) -C(8) 1.535(3) C(3) -C(8) 1.559(3) C(8) -C(9) 1.497(4) C(4) -C(5) 1.513(3) C(9) -COO) 1.310(4) Bond lengths (A) i n v o l v i n g hydrogen atoms with estimated standard d e v i a t ions i n parentheses Bond Length Bond Length CO ) -HO ) 0.92(2) C(7) -H1(7) 1.03(3) C(3) -H(3) 0.95(3) C(7) -H2(7) 0.98(2) C(4) -H1(4) 0.95(3) C(8) -H(8) 0.97(2) C(4) -H2(4) 0.93(3) C(9) -H(9) 0.92(3) C(6) -H(6) 0.92(2) COO) -H(IO) 0.96(2) c a r b o n y l group i s e s s e n t i a l l y from the l e a s t squares plane of d i s t o r t e d n o t i c e a b l y from an showing a C(8)-C(9)-C(10)-C(1) t o r s i o n angles i n the f i v e twistenone (IV) are recorded i n 1 30 plan a r with an average d e v i a t i o n 0.0027 A. The alkene moiety i s u n s t r a i n e d p l a n a r c o n f i g u r a t i o n t o r s i o n angle of 7.4°. Other unique six-membered r i n g s of the F i g u r e 17. As to be expected, Table XXXII Least squares planes (x, y, z are f r a c t i o n a l c o o r d i n a t e s r e f e r r e d to the m o n o c l i n i c c e l l ) Plane 1 d e f i n e d by atoms C(1), C ( 2 ) , C(3) and 0(2) Equ a t i o n : 1.5130x - 6.9114y + 5.3785z - 3.9547 = 0 D e v i a t i o n s from the plane: atom d e v i a t i o n (A) C(1) 0.0018(20) C(2) -0.0083(19) C(3) 0.0035(22) 0(2) 0.0030(18) Plane 2 d e f i n e d by atoms C(4), C(5), C(6) and 0(5) Equ a t i o n : 6.0315X - 4.5660y - 3.2341z - 1.1718 = 0 D e v i a t i o n s from the plane: atom d e v i a t i o n (A) C(4) 0.0036(28) C(5) -0.0047(18) C(6) 0.0010(19) 0(5) 0.0017(16) F i g u r e 17 T o r s i o n angles f o r twistenone (IV) 1 32 the presence of the double bond w i t h i n the t r i c y c l i c s k e l e t o n i n t r o d u c e s marked d e v i a t i o n s from the twistane geometry where the f i v e r i n g s approach t w i s t - b o a t conformations. I d e a l t o r s i o n angles f o r t w i s t - b o a t conformers (38) are presented i n F i g u r e 18 along with t o r s i o n angles f o r twistane obtained by e m p i r i c a l f o r c e - f i e l d c a l c u l a t i o n s (47). D e s p i t e s i g n i f i c a n t d i f f e r e n c e s between twistane t o r s i o n angles (and s i m i l a r l y those of the present molecule) and the i d e a l i z e d t w i s t - b o a t t o r s i o n angles, these angles seem more c o n s i s t e n t with t h i s conformation than with any o t h e r . The D 2-symmetry of the twistane i s d r a s t i c a l l y reduced to C, with the a d d i t i o n of 0(2) and 0 ( 5 ) . Notwithstanding the change i n h y b r i d i z a t i o n at carbons 2 and 5, e x c l u s i o n of the oxygens leaves the t r i c y c l i c s k e l e t o n with symmetry c l o s e l y approximating C 2 (see F i g . 19). The r o t a t i o n a x i s passes through the c e n t e r of, and i s p e r p e n d i c u l a r to bonds C(9)=C(10) and C ( 4 ) - C ( 5 ) , s i m i l a r to the pseudo C 2 - a x i s i n aza-twistanone (48). In a d d i t i o n to t o r s i o n a l s t r a i n , twistenone (IV) s u f f e r s from c o n s i d e r a b l e angular s t r a i n . Compared with normal v a l u e s , e n d o c y c l i c angles are observed to d e v i a t e up to 12.4° with the most n o t i c e a b l e divergence from accepted values o c c u r r i n g f o r angles i n v o l v i n g the oxygen b e a r i n g carbon atoms as v e r t i c e s ; C ( 1 ) - C ( 2 ) - C ( 3 ) , 107.6(2)° and C ( 4 ) - C ( 5 ) - C ( 6 ) , 111.6(2)° (Table XXXIII). Of s i m i l a r magnitude i s the d i f f e r e n c e between the C(2)-C(1)-C(10) angle of 97.9(2)° and the normal t e t r a h e d r a l value of 109.5° suggesting marked d e v i a t i o n from s p 3 h y b r i d i z a t i o n at C ( 1 ) . Other angles which i n c l u d e one b r i d g i n g carbon, f l a n k e d on e i t h e r s i d e by carbons not i n v o l v e d i n a 1 33 C(1) C(2) C(3) C(4) -70.6 C(2) C(3) C(4) C(5) 33.1 C(3) C(4) C(5) C(6) 33.1 C(4) C(5) C(6) C(1) -70.6 C(5) C(6) C(1) C(2) 33.1 C(6) C(1) C(2) C(3) 33.1 5 4 (a) (b) F i g u r e 18 T o r s i o n angles i n twistane (a) and i n the i d e a l i z e d t w i s t - b o a t conformation ( b ) . Values i n (a) are from e m p i r i c a l f o r c e - f i e l d c a l c u l a t i o n s (47); those i n (b) are from r e f e r e n c e 38. bridge (e.£. C ( 2 ) - C ( 3 ) - C ( 4 ) ) , show a mean compression of 6.8° from the i d e a l t e t r a h e d r a l v a l u e . Despite the accuracy with which the bond lengths were obtained, i t i s s t i l l i n s u f f i c i e n t to allow one to q u a n t i f y d e t a i l e d h y b r i d i z a t i o n d i f f e r e n c e s s t r i c t l y on the b a s i s of small changes (<0.01 A) i n v a r i o u s bond d i s t a n c e s . However, from the o v e r a l l bonding geometry the f r a c t i o n of s - c h a r a c t e r i n the h y b r i d o r b i t a l s a s s o c i a t e d with each atom may be c a l c u l a t e d approximately, thereby g i v i n g a c l e a r e r i n d i c a t i o n as to the h y b r i d i z a t i o n w i t h i n p a r t i c u l a r bonds. For example, the 134 F i g u r e 19 Stereo diagram of the twistenone (IV) f r a c t i o n a l s - c h a r a c t e r at the carbon atom C(1), i n the bond C( 1 ) - C ( 2 ) , i s about 0.145, suggesting the involvement of a h y b r i d o r b i t a l q u i t e d i f f e r e n t from s p 3 . An almost equal value of 0.186 f o r the f r a c t i o n a l s - c h a r a c t e r at C(3), i n the C(2)- C(3) bond, i m p l i e s s i m i l a r h y b r i d i z a t i o n . These values, not uncommon in s t r a i n e d systems, r e f l e c t the d i s t r i b u t i o n of the e l e c t r o n s accomodating that p a r t of the s t r u c t u r e . As mentioned above, the C(9)-C(10) bond, 1.310(4) A, i s s i g n i f i c a n t l y d i f f e r e n t from the accepted C ( s p 2 ) - C ( s p 2 ) l e n g t h of 1.335(5) A, but t h i s does not appear to be accompanied by h y b r i d i z a t i o n d i f f e r e n c e s . The amount of s - c h a r a c t e r was c a l c u l a t e d to be 32% at both C(9) and C(10), as expected f o r s p 2 h y b r i d s ; however, the t w i s t of 7.4(3)° about the C(9)-C(10) bond, expected to r e s u l t i n a decrease i n the p - o r b i t a l o v e r l a p between these 1 35 Table XXXIII Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C O ) -CO ) -C(6) 106 .8(2) C ( 4 ) -C(5) -0(5) 123 .2(2) C O ) -CO) -COO) 97 .9(2) C(6) -C(5) -0(5) 125 .2(2) C(6) -CO) -COO) 1 1 2 .5(2) C(5) -C(6) -C(7) 1 03 .8(2) C(3) -CO) -CO) 1 07 .6(2) C(5) -C(6) -CO ) 107 .8(2) C(3) -CO ) -0(1 ) 126 .9(2) C(7) -C(6) -CO ) 109 .0(2) C O ) - c o ) -0(1 ) 125 .5(2) C(6) -C(7) -C(8) 104 .2(2) C O ) -C(3) -C(4) 100 .7(2) C(3) -C(8) -C(7) 108 .0(2) C O ) -C(3) -C(8) 1 07 .5(2) C(3) -C(8) -C(9) 108 .8(2) C ( 4 ) -C(3) -C(8) 1 1 1 .9(2) C(7) -C(8) -C(9) 103 .5(2) C(3) -C ( 4 ) -C(5) 108 . 1(2) C(8) -C(9) -COO) 1 14 .5(2) C(4) -C(5) -C(6) 1 1 1 .6(2) C(9) -COO) -CO ) 1 14 .3(2) Bond angles (deg) i n v o l v i n g hydrogen atoms with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C O ) -CO ) -HO) 111. 6( 13) C O ) -C(6) -H(6) 110. 4(12) C(6) -CO) -H(1 ) 113. 0( 14) C(6) -C(7) -H1(7) 1 12. 8(13) COO) -CO ) -H( 1 ) 113. 8< 13) C(6) -C(7) -H2(7) 109. 0(13) C O ) -C(3) -H(2) 113. 1 < 14) C(8) -C(7) -H1(7) 110. 8(14) C(4) -C(3) -H(2) 111. 1 < 15) C(8) -C(7) -H2(7) 112. 1(12) C(8) -C(3) -H(2) 112. 1 ( 14) H1 (7) -C(7) -H2(7) 1 08. 0(18) C(3) -C(4) -H1(4) 111. 1 I 18) C(3) -C(8) -H(8) 109. 0(13) C(3) -C(4) -H2(4) 110. 4< 14) C(7) -C(8) -H(8) 112. 3 0 4 ) C(5) -C(4) -H1(4) 108. 41 16) C(9) -C(8) -H(8) 115. 0(14) C(5) -C(4) -H2(4) 106. 4< 13) C(8) -C(9) -H(9) 120. 2 0 8 ) H1 (4) -C(4) -H2(4) 112. 21 22) COO) -C(9) -H(9) 125. 1 0 8 ) C(5) -C(6) -H(6) 112. 3< 13) C(9) -COO) -HO0) 124. 7(14) C(7) -C(6) -H(6) 113. 31 12) C O ) -COO) -H(10) 120. 3(14) 136 atoms, should lengthen the bond. C r y s t a l packing i s u n l i k e l y to cause the decrease i n the bond l e n g t h ; a l l i n t e r m o l e c u l a r c o n t a c t s correspond to normal van der Waals d i s t a n c e s . A packing diagram i s presented i n F i g u r e 20. Stereo packing F i g u r e diagram 20 of twistenone (IV) CHAPTER VI 5-(2,3-DIMETHYLPHENYL)-y-BUTYROLACTONE 138 I n t r o d u c t i o n Photochemical s t u d i e s combined with c r y s t a l s t r u c t u r e a n a l y ses on s u b s t i t u t e d 4ap,5,8,8ap-tetrahydro-1,4- naphthoquinones and 4ap,5,8,8ap-tetrahydro-1-naphthoquin-4-ols have p r o v i d e d v a l u a b l e i n s i g h t s i n t o such photochemical r e a c t i o n s as H - a b s t r a c t i o n s (Part I and r e f e r e n c e s 26,30,32,34), d i m e r i z a t i o n s (34) and [2+2] i n t r a m o l e c u l a r c y c l o a d d i t i o n s (26,49). However, some r e a c t i o n s , though designed to c l a r i f y or c o n f i r m a p a r t i c u l a r aspect of a p r e v i o u s l y i n t e r p r e t e d mechanism, have l e d to i n t e r e s t i n g r e s u l t s which s t r a y e d s l i g h t l y from the o r i g i n a l theme of the study. I t has been observed, f o r example, that minor m o d i f i c a t i o n s i n technique along the photochemical experimentation route, as i n the case of the p h o t o l y s i s of the u n s u b s t i t u t e d tetrahydronaphthoquinone (see Chapter V), has an i n t e r e s t i n g and s i g n i f i c a n t e f f e c t on the r e s u l t i n g product r a t i o s . The present compound, shown by X- ray a n a l y s i s to be a 2,3-dimethylphenyl s u b s t i t u t e d y- b u t y r o l a c t o n e 1 , and i t s formation sequence are regarded with equal i n t e r e s t . I t s immediate p r e c u r s o r , r e s u l t i n g from the p h o t o l y s i s of 6,7-dimethyl-4ap,5,8,8ap-tetrahydro-1,4- naphthoquinone has not yet been c h a r a c t e r i z e d . I t was hoped that the s t r u c t u r a l e l u c i d a t i o n of the present compound would a i d i n the d e t e r m i n a t i o n of the i n t e r m e d i a t e compound in the r e a c t i o n scheme. 1 A l t e r n a t i v e IUPAC name: 5-(2,3-dimethylphenyl)-tetrahydro-2- furanone. 1 3 9 Experimental P h o t o l y s i s of 6 , 7 - d i m e t h y l - 4 a p , 5 , 8 , 8 a p - t e t r a h y d r o - 1 , 4 - naphthoquinone (V) ( F i g . 2 1 ) gave the p r e v i o u s l y observed y- hydrogen a b s t r a c t i o n product (VI) and a new product X. (VII) F i g u r e 21 Reaction scheme l e a d i n g to the l a c t o n e ( V I I ) . T hermolysis of the minor product X y i e l d e d the t i t l e compound (VII) which was r e c r y s t a l l i z e d from a petroleum e t h e r / e t h a n o l s o l u t i o n . The c r y s t a l chosen f o r s t r u c t u r e a n a l y s i s was bounded by s i x w e l l - d e f i n e d faces ±(102), ±(10T) and ±(01~), and measured 0 . 1 4 x 0 . 0 4 x 0 . 0 6 mm3. C r y s t a l d a ta: C 1 2 H U 0 2 , MW = 1 9 0 . 2 4 , m o n o c l i n i c a = 1 0 . 8 4 7 ( 3 ) , b = 6 . 9 2 4 ( 1 ) , c = 1 3 . 6 5 4 ( 4 ) A , p = 9 5 . 2 2 ( 1 ) ° , V = 1 0 2 1 . 3 ( 5 ) A 3 , Z = 4 , D C = 1 . 2 3 7 g cm" 3, D Q = 1 . 2 4 4 g cm" 3, M ( M O K O ) = 0 . 4 6 8 cm" 1, X. = 0 . 7 1 0 7 3 A , space group P 2 , / n , from s t r u c t u r e a n a l y s i s . 1 40 Data were c o l l e c t e d between 0.0 and 22.5° ( g r a p h i t e monochromatized MoKc r a d i a t i o n ) with u-2e scans and speeds ranging from 1.44 to 10.06 deg min* 1. The omega scan angle was given by (0.90 + 0.35tane)°. The h o r i z o n t a l a p e r t u r e width was c a l c u l a t e d from the e x p r e s s i o n (2.00 + tan©) mm and the v e r t i c a l a p e r t u r e remained constant at 4 mm. I n t e n s i t y c o n t r o l r e f l e c t i o n s were monitored every 3600 seconds of X-ray exposure time and c r y s t a l o r i e n t a t i o n was checked a f t e r every 100 r e f l e c t i o n s c o l l e c t e d . F i n a l c e l l parameters were obtained by l e a s t squares f i t of the parameters t o the si n e v a l u e s f o r 18 cen t e r e d r e f l e c t i o n s . Data p r o c e s s i n g i n c l u d e d c o r r e c t i o n s f o r Lorentz and p o l a r i z a t i o n e f f e c t s but not f o r a b s o r p t i o n . The maximum decay i n the i n t e n s i t y c o n t r o l s was 2.98% over the e n t i r e data c o l l e c t i o n . 569 of the 1341 r e f l e c t i o n s c o l l e c t e d had I > 3 * ( I ) , where « 2 ( I ) = S + 2B + (0.04(S - B ) ) 2 , S = scan count, B = time- averaged background. S o l u t i o n and Refinement The c r y s t a l d e n s i t y of 1.24 g cm"3 suggested 14 non- hydrogen atoms per asymmetric u n i t and the E - s t a t i s t i c s i n d i c a t e d a c e n t r i c d i s t r i b u t i o n of these atoms throughout the c e l l . From the 256 l a r g e s t E's, 5301 I 2 - r e l a t i o n s h i p s were generated f o r use i n the phase determining p r o c e s s . No phases were determined by the E,-formula and so MULTAN was per m i t t e d to choose a d d i t i o n a l s t a r t i n g r e f l e c t i o n s with r e l a t i v e l y l a r g e E value s and which o c c u r r e d f r e q u e n t l y i n the ^ " l i s t i n g . The 141 phases of the g e n e r a l r e f l e c t i o n s were to be permuted, thereby g e n e r a t i n g d i f f e r e n t phase s e t s d u r i n g the phase d e t e r m i n a t i o n . Three o r i g i n d e f i n i n g r e f l e c t i o n s were chosen a c c o r d i n g to the centrosymmetric m o n o c l i n i c space group c r i t e r i a . The set of phases accepted as the true s o l u t i o n had the best f i g u r e s of m e r i t . A subsequent F o u r i e r s y n t h e s i s using the normalized s t r u c t u r e s f a c t o r s (with t h e i r newly found phases) as c o e f f i c i e n t s r e v e a l e d the p o s i t i o n s of a l l non-hydrogen atoms. F u l l matrix l e a s t squares refinement was i n i t i a t e d i n the space group P2y/n, with the i n c l u s i o n of non-hydrogen atoms with i s o t r o p i c temperature f a c t o r s . U n i t weights were employed in the i n i t i a l stages of the refinement. Conversion to a n i s o t r o p i c temperature f a c t o r s was f o l l o w e d by f u r t h e r c y c l i n g and a d i f f e r e n c e s y n t h e s i s which r e v e a l e d c o o r d i n a t e s f o r a l l hydrogen atoms. The hydrogens assumed i s o t r o p i c thermal parameters d u r i n g subsequent refinement. The weighting scheme was changed to w = 1/tf 2(F) (where <r 2(F) i s obtained from the e 2{l) d e f i n e d above) in order to r e f l e c t the accuracy of the data. As the refinement proceeded i t was noted that what i n i t i a l l y appeared as reasonable bonding geometries f o r hydrogens on C(8) and C(9) had become c h e m i c a l l y unreasonable, fo r each p a i r of hydrogens at these carbons had c o a l e s c e d i n t o s i n g l e peaks. At t h i s p o i n t , bond lengths and angles were c a l c u l a t e d i n an e f f o r t to determine the bond order between C(8) and C ( 9 ) . A l l bore reasonable semblance to accepted values (33) with the e x c e p t i o n of those i n c l u d i n g C(8) and C ( 9 ) . For example, the C(8)-C(9) bond l e n g t h of 1.42 A seemed very short fo r a s i n g l e bond in that environment, and y e t , was extremely 1 42 long f o r a double bond. E x c l u d i n g the a f f e c t e d hydrogens, the remainder of the molecule accounted f o r 186 mass u n i t s (m.u.) which was 4 m.u. l e s s than the parent ion peak observed i n the mass spectrum. T h i s l e f t l i t t l e doubt as to the number of m i s s i n g hydrogens, and so i t was concluded that C(8) and C(9) were methylene carbons. I n s p e c t i o n of the thermal parameters f o r these 2 carbons r e v e a l e d anomalously l a r g e r.m.s. v i b r a t i o n s , up to 0.5 A f o r C(8), roughly p e r p e n d i c u l a r to the mean plane of the five-membered r i n g . T h i s s i t u a t i o n of apparent h i g h thermal motion out of the plane, combined with unusual bonding geometry around C(8) and C(9) c l o s e l y p a r a l l e l s t h a t found i n the f i v e - membered r i n g metal complexes, MejXCR'R 2.CF 2XMe 2.M(CO)« (50) where the presence of d i s o r d e r accounted f o r the seemingly unreasonable geometry. S i m i l a r d i s o r d e r was thought to occur i n the present s t r u c t u r e . The l i m i t e d number of data r e s t r i c t e d the h a n d l i n g of the d i s o r d e r to C(8) and i t s corresponding hydrogens. Two carbon atoms with i s o t r o p i c temperature f a c t o r s r e p l a c e d the o r i g i n a l C(8) i n the refinement and were i n i t i a l l y g iven equal occupancies 1 A apart on the v e c t o r normal to the mean plane of the furanose r i n g and p a s s i n g through the o r i g i n a l C(8) c o o r d i n a t e s . From the magnitude of the temperature f a c t o r s a f t e r s e v e r a l c y c l e s of refinement, i t was concluded that the p o s i t i o n s of C(8)' and C(8)" were occupied i n the r a t i o of 60:40. Four hydrogen atoms were found v i a a d i f f e r e n c e map and r e f i n e d along with t h e i r i s o t r o p i c thermal parameters. The standard d e v i a t i o n i n an o b s e r v a t i o n of u n i t weight was 3.3 when w = l/o- 2(F) (which was probably due to the incomplete 143 handli n g of the d i s o r d e r ) . In the f i n a l c y c l e the polynomial weighting scheme w = (A + BFo + CFo 2 + D F o 3 ) " 1 , where A 0.3957, B = 0.00000, C = -0.004568 and D = 0.000384, was employed. T h i s gave constant averages of wA2 over ranges of Fo. Mean and maximum parameter s h i f t s on the l a s t c y c l e of refinement were 0.233 and 1.201©*, r e s p e c t i v e l y ; the maximum s h i f t o c c u r r e d i n the temperature f a c t o r of C ( 8 ) " . The f i n a l R- value f o r 569 r e f l e c t i o n s with I > 3©*(I) was 0.057 while that f o r Rw was 0.065. For the e n t i r e data set (1341 r e f l e c t i o n s ) R = 0.141 and Rw = 0.066. A d i f f e r e n c e - F o u r i e r s y n t h e s i s f o l l o w i n g refinement showed random f l u c t u a t i o n s between 0.156 and -0.220 © e/A 3. A l i s t of c o o r d i n a t e s and temperature f a c t o r s i s given i n Table XXXIV. A n i s o t r o p i c thermal parameters are presented i n Table XXXV. Di s c u s s i o n The s t r u c t u r e c o n s i s t s of a 2,3-dimethylphenyl s u b s t i t u e n t bonded to the r-carbon of a b u t y r o l a c t o n e moiety. C o n s i d e r i n g only the gross conformation, the molecule may be d e s c r i b e d as two r i n g - c o n t a i n i n g m o i e t i e s ( F i g . 22) whose mean planes through the r i n g s subtend a d i h e d r a l angle of 70°. The molecules pack with the l a c t o n e r i n g s back-to-back and l i e almost p a r a l l e l to the (301) p l a n e . T h i s i s c o n s i s t e n t with the r e l a t i v e l y l a r g e E- magnitude of 3.23 found f o r the 30? r e f l e c t i o n . S i m i l a r l y , the pr o x i m i t y of the phenyl r i n g atoms to the (113) plane seems to account f o r i t s E-magnitude of 4.66, the l a r g e s t i n the data s e t . i 1 44 Table XXXIV F i n a l p o s i t i o n a l ( f r a c t i o n a l x lOVH X 10 3) and i s o t r o p i c thermal parameters (U x 10 3 A 2) with estimated standard d e v i a t i o n s i n parentheses Atom 2 X 1 z Ueq/Uiso C(1 ) 5386( 6) -879( 7) 1 867 ( 4) 71 C(2) 5493( 6) 8 1 3 ( 7) 1 3 1 3 ( 4) 66 C(21 ) 4454(1 1 ) 22S2( 11) 1 2 1 6 ( 8) 90 C(3) 6569( 7) 1 1 741 • 9) 854( 4) 74 C(31 ) 6724(13) 2952< 12) 256( 7) 1 10 C(4) 7510( 8) -1671 12) 944( 6) 89 C(5) 7437( 9) -18041 11) 1 500 ( 6) 92 C(6) 6373( 9) -21761 10) 1 939 ( 5) 87 C(7) 4233( 1 1 ) -12631 9) 2366( 7) 100 C(8) ' 3958(17) -326< r17) 3301 ( 1 1 ) 76( 4) C (8 ) " 4691(20) -464 ,22) 3555(12) 62( 4) C(9) 4208( 7) -1940 ,10) 4050( 5) 102 C( 10) 4101( 6) -3764 [ 9) 3463( 6) 82 0(1 ) 3999( 5) -5396 ; 7) • 3737( 4) 121 0(2) 4078( 5) -3332 [ 5) 2526( 4) 1 05 H1(21 ) 372( 7) 2 1 4 ( 0) 1 58 ( 5) 121(31) H2(21) 478( 7)' 330( 2) 1 47 ( 6) 114(31) H3(21 ) 395(11) 221 ( 4) 60( 9) 188(49) H1(31 ) 604( 7) 3 1 3 ( 1) -26( 6) 120(31) H2(31 ) 742( 8) 327( 3) -5( 7) 129(38) H3(31 ) 687( 7) 421 ( 12) 72( 6) 147(27) H(4) 820( 5) 3( 7) 68( 4) 61(20) H(5) 807( 7) -280( 11) 1 57 ( 5) 106(24) H(6) 623( 6) -3 1 7 ( 1 1 ) 236( 5) 104(23) H(7) 361( 6) -86( 10) 1 89 ( 6) 98(28) H1(8) ' 306( 9) -32( 12) 348( 6) 77(28) H2(8)' 459( 7) 1 07 ( 12) 340( 5) 50(22) H1 (8 ) " 547(1 1 ) -86( 15) 383( 7) 39(30) H2(8) " 424(10) -1 3( 16) 302(1 0) 20(32) H1(9)* 496 -1 94 447 1 36 H2(9)* 353 -181 443 1 36 2 Primed (') atoms are at 60% occupancy; double primed (") atoms are at 40% occupancy; a s t e r i s k s (*) denote atoms i n c a l c u l a t e d p o s i t i o n s . 145 Table XXXV F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10 3 A 2) and t h e i r estimated standard d e v i a t i o n s Atom u 2 2 U 3 3 U, 2 U , 3 y 2 3 c(D 1 07 ( 5) 48( 4) 58( 4) 17( 4) 1 ( 4) -5( 3) C(2) 87( 5) 47( 3) 61( 4) 10( 3) -13( 3) -11 ( 3) C(21 ) 1 06 ( 7) 55( 4) 1 06 ( 6) 23( 5) -8( 6) -6( 4) C(3) 96( 5) 58( 4) 63( 4) 4( 4) -11 ( 4) -19( 3) C(31 ) 167(10) 73( 5) 90( 6) -25( 6) 14( 8) 3( 4) C(4) 91 ( 6) 83( 5) 93( 5) -6( 5) 17( 5) -32( 4) C(5) 1 05 ( 7) 78( 5) 89( 5) 32( 5) -12( 5) -19( 4) C(6) 1 24 { 7) 60( 4) 75( 4) 28( 5) 5( 5) 6( 3) C(7) 171 ( 9) 48( 4) 85( 5) 10( 5) 34( 6) 2( 4) C(9) 1 36 ( 7) 67( 4) 1 03 ( 5) -9( 5) 12( 5) -17( 4) COO) 87( 5) 53( 4) 1 10( 5) -11 ( 4) 42( 4) -11 ( 4) 0(1 ) 1 65 ( 5) 56( 3) 1 53 ( 5) -18( 3) 73( 4) 0( 3) 0(2) 1 75 ( 5) 49( 3) 95( 3) -6( 3) 29( 3) -13( 3) 1 46 F i g u r e 22 Stereo view of the l a c t o n e ( V I I ) . A d e t a i l e d d e s c r i p t i o n of the s t r u c t u r e i s l i m i t e d by the accuracy of the d e r i v e d q u a n t i t i e s , which in turn i s a d v e r s e l y a f f e c t e d by the d i s o r d e r i n the s t r u c t u r e . Some general a s p e c t s , however, are noteworthy and are d e s c r i b e d below. B u t y r o l a c t o n e r i n g s u s u a l l y assume an envelope conformation (51,52) where the only atom d e v i a t i n g s i g n i f i c a n t l y from the plane of the remaining four i s the p-carbon. The p l a n a r i t y of the remaining atoms i n the r i n g stems from the c a r b o n y l group and the p a r t i a l s p 2 - c h a r a c t e r of the hetero-oxygen atom. Incomplete h a n d l i n g of the d i s o r d e r prevented o b s e r v a t i o n of 147 t h i s conformation in the present s t r u c t u r e , however, the conformation may be i n f e r r e d from the nature of the d i s o r d e r . G e n e r a l l y , the bond lengths and angles (Tables XXXVI and XXXVII) agree with those given by Harlow and Simonsen (52), for a s i m i l a r r - l a c t o n e . D e v i a t i o n s i n these d e r i v e d q u a n t i t i e s i n v o l v i n g C(8)' and C ( 8 ) " i n d i c a t e that the d i s o r d e r i s not c o n f i n e d to only one atom in the r i n g . Examination of the r.m.s. thermal displacements of each of the l a c t o n e atoms r e v e a l s the extent of the d i s o r d e r . The s t e r e o diagrams included in F i g u r e s 22 and 23 show the r e l a t i v e s i z e s of the thermal e l l i p s o i d s before the d i s o r d e r at C(8) was r e f i n e d . The phenyl r i n g i s s i g n i f i c a n t l y non-planar as i n d i c a t e d by the c h i - s q u a r e d value of 8.9 f o r 3 degrees of freedom. C(4) and F i g u r e 23 Stereo view of the contents of the u n i t c e l l . 148 Table XXXVI Bond le n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length c ( i ) -C(2) 1 .405(7) C(7) -C(8)' 1 .49(2) C O ) -C(6) 1 .394(9) c m -C(8)" 1 .74(2) C O ) -C(7) 1 .502(10) c m -0(2) 1 .461(8) C(2) -C(21) 1 .505(10) C(8) -C(9) 1 .52305) C(2) -C(3) 1 .397(8) C ( 8 ) " -C(9) 1 .357(15) C(3) -C(31) 1 .496(10) C(9) -COO) 1 .495(8) C(3) -C(4) 1 .377(9) COO) -0(1 ) 1 .199(7) C(4) -C(5) 1 .371(11 ) COO) -0(2) 1 .312(8) C(5) -C(6) 1 .372(10) Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -CO ) -C(6) 118 .3(7) C O ) - c m -0(2) 1 10 .7(6) c m -CO ) -C(7) 120 .3(6) C(8) ' - c m - C ( 8 ) " 28 .9(7) C(6) -CO ) -C(7) 121 .3(6) C(8) ' - c m -0(2) 105 .4(7) C O ) -C(2) -C(21) 120 .3(7) C ( 8 ) " - c m -0(2) 101 .5(8) C O ) -C(2) -C(3) 1 20 .2(5) c m -C(8)' -C(9) 102 .7(8) C(21 ) -C(2) -C(3) 119 .4(7) c m -C(8 ) " -C(9) 97 .7(10) C(2) -C(3) -C(31) 122 .2(7) C(8) ' -C(9) - C ( 8 ) " 33 .5(9) C(2) -C(3) -C(4) 118 .9(6) C(8) * -C(9) -COO) 1 05 .0(7) C(31 ) -C(3) -C(4) 119 .0(8) C ( 8 ) " -C(9) -COO) 1 12 .6(8) C(3) -C(4) -C(5) 121 .8(8) C(9) -COO) -0( 1 ) 1 29 .3(7) C(4) -C(5) -C(6) 119 .3(8) C(9) -COO) -0(2) 108 .9(5) C O ) -C(6) -C(5) 121 .3(7) 0( 1 ) -COO) -0(2) 121 .7(6) C O ) -C(7) -C(8)' 123 .6(11) C(7) -0(2) -COO) 1 12 .1(6) C O ) -C(7) -C( 8 ) " 100 .8(9) 1 49 Table XXXVII Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length Bond Length C(21) -H1(21) 0.99(7) C(6) -H(6) 0 .92(7) C(21) -H2(21) 0.86(8) C(7) -H(7) 0 .94(7) C(21) -H3(21) 0.96(12) C(8) -H1(8)' 1 .02(8) C(31) -H1(31) 0.99(8) C(8)' -H2(8)' 1 .19(8) C(31) -H2(31) 0.92(8) C ( 8 ) " -H1(8)" 0 .94(11) C(31) -H3(31) 1.08(8) C ( 8 ) " -H2(8)" 0 .87(11) C(4) -H(4) 0.87(5) C(9) -H1(9) 0 .95(8) C(5) -H(5) 0.97(8) C(9) -H2(9) 0 .95(8) Bond angles i n v o l v i n g hydrogen atoms (deg) with estimated standard d e v i a t i o n s in parentheses Bonds Angle Bonds Angle C(2) -C(21)-H1(21) 122(4) C ( 8 ) " -C(7) -H(7) 133(4) C(2) -C(21)-H2(21) 104(5) 0(2) -C(7) -H(7) 108(4) C(2) -C(21)-H3(2l) 114(6) C(7) -C(8)'- H1 (8) ' 118(5) H1(21)-C(21)-H2(2l) 101(7) C(7) -C(8)'- H2(8) ' 107(4) H1(21)-C(2l)-H3(21) 91(7) C(9) -C(8) H1 (8) 88(5) H2(21)-C(21)-H3(21) 124(8) C(9) -C(8) '-H2(8) ' 117(4) C(3) -C(31)-H1(31) 112(4) H1(8)' -C(8)'- H2(8) ' 122(6) C(3) -C(31)"H2(31) 126(6) C(7) - C ( 8 ) n - HI (8) " 117(6) C(3) -C(31)-H3(31) 111(4) C(7) -C(8P- H2(8) 38(8) H1(31)-C(31)-H2(31) 104(7) C(9) -C(8)"- H1 (8) 88(6) H1(31)-C(31)-H3(31) 112(7) C(9) -C(8)"- H2(8) " 114(7) H2(31)-C(31)"H3(31) 89(7) H1 ( 8 ) " -C(8P- H2(8) " 146.7(1) C(3) -C(4) -H(4) 121(4) C(8) ' -C(9) - H1 (9) 119.6(9) C(5) -C(4) -H(4) 117(4) C(8) ' -C(9) - H2(9) 101.2(9) C(4) -C(5) -H(5) 124(4) C ( 8 ) " -C(9) - H1 (9) 87.2(1 ) C(6) -C(5) -H(5) 116(4) C(8P -C(9) - H2(9) 123.7(1) C(1) -C(6) -H(6) 111(4) COO) -C(9) - H1 (9) 110.0(6) C(5) -C(6) -H(6) 128(4) COO) -C(9) - H2(9) 110.4(6) C(1) -C(7) -H(7) 102(4) HI (9) -C(9) - H2(9) 110.1(7) C(8)' -C(7) -H(7) 106(5) I Table XXXVIII T o r s i o n angles (deg) with estimated standard d e v i a t i o n s i n parentheses Atoms Value C(6) -CO) -C(2) -C(21) - 179.8( 7) C(6) -CO) -C(2) -C(3) 0.4( 8) C(7) -CO) -C(2) -C(21) 0.2( 9) C(7) -CO) -C(2) -C(3) 179.6( 7) C(2) -CO) -C(6) -C(5) 1 .4( 8) C(7) -CO) -C(6) -C(5) -178.5( 7) C(2) -CO) -C(7) -C(8)' -78. 1 ( 12) C(2) -CO) -C(7) -C(8)" -97.6( 9) C(2) -CO) -C(7) -0(2) ' 155.7( 6) C(6) -CO) -C(7) -C(8)' 101.8( 10) C(6) -CO) -C(7) -C(8)" 82.4( 8) C(6) -CO) -C(7) -0(2) -24.4( 1 1 ) C(1 ) -c(2) -C(3) -C(31) 179.9( 6) C O ) -C(2) -C(3) -C(4) 0.9( 7) C(21 ) -C(2) -C(3) -C(31) 0.7( 9) C(21 ) -C(2) -C(3) -C(4) -179.7( 7) C(2) -C(3) -C(4) -C(5) -2.6I 9) C(31 ) -C(3) -C(4) -C(5) 178.41 7) C(3) -C(4) -C(5) -C(6) 3.6 10) C(4) -C(5) -C(6) -CO ) -3.0 [9) C O ) -C(7) -C(8)' -C(9) -104.9 [10) C(8) n -C(7) -C(8)' -C(9) -62.3 (14) 0(2) -C(7) -C(8)' -C(9) 23.6 [15) C O ) -C(7) -C( 8 ) " -C(9) -136.8 10) C(8) » -C(7) -C(8)" -C(9) 78(2 0(2) -C(7) -C( 8 ) " -C(9) -22.9 J 3 ) C O ) -C(7) -0(2) -COO) 118.0 (7) C(8) t -C(7) -0(2) -COO) -17.8 0 3 ) C(8) n -C(7) -0(2) -C(10) 11.7 ( 1 1 ) C(7) -C(8)' -C(9) -C(8)" 86(2 C(7) -C(8)' -C(9) -COO) -21.8 :n) C(7) -C(8)" -C(9) -C(8)' -56.9 0 5 ) C(7) -C(8)" -C(9) -COO) 26.3 (14) C(8] i -C(9) -COO) -0(1 ) -165.0 (10) C(8) l -C(9) -COO) -0(2) 12.2 (10) C(8 II -C(9) -COO) -0(1 ) 160.5 0 2 ) C(8 II -C(9) -COO) -0(2) -22.3 (13) C(9 -COO) -0(2) -C(7) 3.2 (9) 0(1 -COO) -0(2) -C(7) -179.3 (7) C(2 -CO ) -C(6) -H(6) 175(5 C(7 -CO) -C(6) -H(6) -5(5 C(2 -CO) -C(7) -H(7) 41(4 C(6 -CO) -C(7) -H(7) -139(4 C O -C(2) -C(21) -H1(21) 6(5 Table XXXVIII (continued) C( 1 ) -c( 2) -c( 21 ) -H2(21) 1 191 5 C( 1 ) -c( 2) -c( 21 ) -H3(21) -1 02 < 7 C(3) -c( 2) -c( 21 ) -H1(21) -1731 5 C(3) -c( 2) -c( 21 ) -H2(21) -601 5 C(3) -c( 2) -c( 21 ) -H3(21) 781 ,7 C(2) -c( 3) -c( 31 ) -H1(31) -531 ,5 C(2) -c( 3) -c( 31 ) -H2(31) 1 79 ,7 C(2) -c( 3) -c( 31 ) -H3(31) 74 [4 C(4) -c( 3) -c( 31 ) -H1(31 ) 1 25 (5 C(4) -c( 3) -c( 31 ) -H2(31 ) -2 (7 C(4) -c( 3) -c( 31 ) -H3(31 ) -1 07 [4 C(2) -c( 3) -c( 4) -H(4) -1 79 (4 C(31 ) -C( 3) -c( 4) -H(4) 2 (4 C(3) -c( 4) -c( 5) -H(5) 178 (5 H(4) -c( 4) -c( 5) -C(6) 180 (4 H(4) -c( 4) -c( 5) -H(5) -5 (6 C(4) -C( 5) -c< 6) -H(6) -1 76 (5 H(5) -c< 5) -CI 6) -C(1) -178 (5 H(5) -c< 5) -CI 6) -H(6) 9 (7 C( 1 ) -CI 7) -c< 8) -H1(8)' 161 (6 C( 1 ) -CI 7) -c< 8) -H2(8)' 19 (4 C ( 8 ) " -CI 7) -c< 8) -H1(8)' -1 56 (6 C(8)" -c< 7) -c< 8) -H2(8)' • 61 (4 0(2) -CI 7) -c 8) -HI(8)' -71 (6 0(2) -c< 7) -c 8) -H2(8)' 1 47 (4 H(7) -CI 7) -c '8) -C(9) 1 38 (4 H(7) -c ,7) -c 8) -H1(8)' 44 (7 H(7) -c 7) -c ,8) -H2(8)' -98 (6 C( 1 ) -c ,7) -c (8) « -H1(8)" -46 (7 C( 1 ) -c [7) -c (8) n -H2(8)" 1 04 ( 1 C(8) ' -c (7) -c (8) n -H1(8)" 169 (8 C(8) ' -c [7) -c (8) it -H2(8)" -41 ( 1 0(2) -c (7) -c (8) it -H1(8)" 68 (7 0(2) -c (7) -c (8) II -H2(8)" -142 ( 1 H(7) -c (7) -c (8) n -C(9) 1 05 (6 H(7) -c [7) -c (8) n -H1(8)" -1 64 (9 H(7) -c (7) -c (8) n -H2(8)" -13 ( 1 H(7) -c (7) -o (2) -C(10) -131 (5 C(7) -c (8) -c (9) -H1(9) 1 02 .2 C(7) -c (8) i -c (9) -H2(9) -1 36 .8 H1 (8) • -c (8) -c (9) -C(8)" -1 55 (5 H1 (8) •-C (8) -c (9) -C(10) 96 (5 HI (8) ' -c (8) » -c (9) -H1(9) -1 40 (5 H1 (8) (8) -c (9) -H2(9) -19 (5 H2(8) ' -c (8) t -c (9) - C ( 8 ) B -31 (4 H2(8) ' -c (8) * -c (9) -C(10) -139 (4 H2(8) •-c (8) * -c (9) -H1(9) -15 (5 H2(8) '-C (8) » -c (9] -H2(9) 106 (4 C(7) -c (8) n -c (9] -H1(9) 136 .7 C(7) -c (8) n -c (9] -H2(9) -110 .8 H1 (8) "-C (8) n -c (9] -C(8)' -174(7 Table XXXVI11 (cont inued) H1(8)" -C(8)" -C(9) -COO) -91(6) H1(8)" -C(8)" -C(9) -H1(9) 20(6) H1(8)" - C ( 8 ) n -C(9) -H2(9) 132(6) H2(8)" -C(8)" -C(9) -C(8)' -20(9) H2(8)" -C(8)" -C(9) -COO) 63(10) H2 (8)" -C(8)" -C(9) -H1(9) 173(10) H2(8)" -C(8)" -C(9) -H2(9) -74(10) H1 (9) -C(9) -C(10) -0(1) 65.1(10) H1 (9) -C(9) -C(10) -0(2) -1 17.7(7) H2(9) -C(9) -COO) -0(1) -56.7(11) H2(9) -C(9) -COO) -0(2) 120.5(7) 1 53 C(5) d e v i a t e from the mean plane c a l c u l a t e d through a l l s i x r i n g carbons by 0.015 and -0.017 A, r e s p e c t i v e l y . I n t r a - a n n u l a r t o r s i o n angles range from -3.0(9) to 3.6(10), Table XXXVIII. S l i g h t d i f f e r e n c e s i n bond l e n g t h s and angles compared to benzene (53) r e f l e c t the e l e c t r o n i c d i s t r i b u t i o n w i t h i n the r i n g . 1 54 CHAPTER VII 1,3,4,5,6, 9-HEXAMETHYL-8-EXO-METHYLENETRICYCLO[ 4 . 4 . 0 . 0 3-9 ]DEC~4- ENE-2-0NE 155 I n t r o d u c t i o n Attempts to a c e t y l a t e the heptamethyl-4p-ol (VIII) l e d to the formation of the exo-methylene ketone (IX) r a t h e r than the a c e t a t e . R e p l a c i n g OH with OAc would have removed the f a c i l i t y f o r hydrogen bonding v i a the h y d r o x y l group hence, the r e a c t i v i t y i n the absence of H-bonding c o u l d have been s t u d i e d . However, with the p r o d u c t i o n of the methylene ketone, i n t e r e s t was d i v e r t e d to i t s photochemistry. The f o l l o w i n g c r y s t a l s t r u c t u r e a n a l y s i s showed that a 1 , 3 - s h i f t r e s u l t e d from the p h o t o l y s i s of (IX) i n s o l u t i o n l e a d i n g t o the is o m e r i c exo- methylene ketone (X). Exper imental F i g u r e 24 shows the r e a c t i o n scheme f o r the generation of the t i t l e compound from 2,3,4a,4ap,6,7,8ap-heptamethyl- 4ap,5,8,8ap-tetrahydronaphthoquin-40-ol (VIII) v i a the intermediate 1,3,6,7,8,9-hexamethyl-4-exo-methylenetricyclo [4.4.0.0 3- 7 ]dec-7-ene-10-one, ( I X ) . R e c r y s t a l l i z a t i o n of methylene ketone (X) from a hexane/acetone s o l u t i o n y i e l d e d t r a n s l u c e n t c r y s t a l s whose faces appeared r e l a t e d by a two-fold r o t a t i o n a x i s p a r a l l e l to the long a x i s of the c r y s t a l s . C r y s t a l d ata: C, 7H 2 aO, MW = 244.36, m o n o c l i n i c a = 12.374(2), b = 8.771(1), c = 13.743(2) A, * « 104.027(6)°, V = 1446.9(3) A 3, Z = 4, D c = 1.122 g cm" 3, ».(MoKa) = 0.626 cm" 1, X = 0.71073 A, space group P ^ / a , from systematic absences and s t r u c t u r e a n a l y s i s . 156 F i g u r e 24 Reaction scheme showing the pro d u c t i o n of the methylene ketone (X). Data were c o l l e c t e d with a c r y s t a l measuring 0.3 x 0.2 x 0.3 mm3 using g r a p h i t e monochromatized MoKo r a d i a t i o n . An u- 2(5/6)6 scan was employed i n c o l l e c t i n g 3297 unique r e f l e c t i o n s between 0.0 and 27.5°. Omega scan widths v a r i e d a c c o r d i n g to the ex p r e s s i o n (0.65 + 0.35tane)° and were extended 25% on each sid e for background measurement. H o r i z o n t a l aperture s e t t i n g s were v a r i e d with t h e t a , the width being given by (2.00 + tane) mm; and the v e r t i c a l aperture remained constant at 4 mm. Scan speeds ranged from 0.91 to 10.06 deg min" 1, the former l i m i t c o r responding to 75 s scans. Data p r o c e s s i n g , which i n c l u d e d a p p l i c a t i o n of Lorentz and p o l a r i z a t i o n c o r r e c t i o n s , i n d i c a t e d that 41.5% (1369 r e f l e c t i o n s ) of the t o t a l r e f l e c t i o n s measured (3297) were c l a s s i f i e d as observed having I £ 3c-(I), where ©-2(I) = (S + 2B + (0.06(S - B ) ) 2 , S = scan count, B = time-averaged background. 157 S o l u t i o n and Refinement The processed data r e v e a l e d that r e f l e c t i o n s of the types hOl, h = 2n + 1 and OkO, k_ = 2n + 1 were c l a s s i f i e d as unobserved thereby suggesting the space group P2,/a. The i n t e n s i t y s t a t i s t i c s compared f a v o r a b l y with the t h e o r e t i c a l c e n t r i c d i s t r i b u t i o n - c o n s i s t e n t with the centrosymmetric space group suggested. The s t r u c t u r e was s o l v e d by d i r e c t methods employed i n MULTAN using 272 of the l a r g e s t E-values to generate 2448 phase r e l a t i o n s h i p s . No phases i n d i c a t e d by the E,- r e l a t i o n s h i p s had a p r o b a b i l i t y of g r e a t e r than 0.90, which was l e s s than the minimum value of 0.95 f o r acceptance. The three o r i g i n f i x i n g r e f l e c t i o n s , chosen to f i t the c r i t e r i a f o r o r i g i n s p e c i f i c a t i o n , were a s s i g n e d i n i t i a l phases of 0. Four other r e f l e c t i o n s which were i n v o l v e d i n many E 2 - r e l a t i o n s h i p s were given s t a r t i n g values of 0, but were permuted with 0 and tr to y i e l d 16 s e t s of phases ( t o t a l phase s e t s = n p , where n = number of s t a r t i n g phases and p = number of p o s s i b l e s t a r t i n g values f o r these phases). The set of phases with the h i g h e s t degree of i n t e r n a l c o n s i s t e n c y ( c a l c u l a t e d as a f i g u r e of merit) was the c o r r e c t set which, when used i n c o n j u n c t i o n with the E's i n c a l c u l a t i n g a F o u r i e r s y n t h e s i s , r e s u l t e d i n an e l e c t r o n d e n s i t y map on which the p o s i t i o n s of the 18 non-hydrogen atoms were l o c a t e d . Refinement was i n i t i a t e d i n the space group P2,/a ( l a t e r confirmed to be the c o r r e c t space group assignment) with 16 carbon atoms and 2 oxygen atoms assuming i s o t r o p i c temperature f a c t o r s . Subsequent c y c l e s with these atoms and a n i s o t r o p i c 158 thermal parameters were f o l l o w e d by d i f f e r e n c e syntheses which r e v e a l e d the p o s i t i o n s of the 24 hydrogens. Convergence was reached a f t e r s e v e r a l c y c l e s of refinement which i n c l u d e d a l l atoms and r e s u l t e d i n an R-value of 0.040, Rw = 0.040. A l i s t of p l anes, where ||Fo| - k|Fc|| d i v i d e d by the e r r o r i n an o b s e r v a t i o n of u n i t weight was g r e a t e r than 3.0, showed s e v e r a l r e f l e c t i o n s which appeared to s u f f e r from e x t i n c t i o n e f f e c t s . An i s o t r o p i c Type I (domain m i s o r i e n t a t i o n ) e x t i n c t i o n c o r r e c t i o n was a p p l i e d assuming the mosaic spread d i s t r i b u t i o n to be Gaussian. Three f u r t h e r refinement c y c l e s produced the f i n a l g- v a l u e , 5.44x10*, where g i s the secondary e x t i n c t i o n c o e f f i c i e n t i n the e x p r e s s i o n | Fo | 2 = |Fc | 2exp(-gY/2|Fc| 2) . The refinement, with e x t i n c t i o n c o r r e c t i o n s , converged at R = 0.037, Rw =.0.039 with mean and maximum parameter s h i f t s of 0.079 and 0.465©-, r e s p e c t i v e l y on the f i n a l c y c l e which had 260 v a r i a b l e s f i t t e d to the 1369 data having I > 3©-(I). For a l l data R = 0.132 and Rw = 0.075. R e f l e c t i o n s were a s s i g n e d weights, w = 1/©-2(F) where ©-2(F) i s d e r i v e d from the o- 2(I) d e f i n e d above. The standard e r r o r i n an o b s e r v a t i o n of u n i t weight was 0.7371. F o l l o w i n g convergence a d i f f e r e n c e - s y n t h e s i s showed random f l u c t u a t i o n s up to 0.l5e/A 3. A l i s t of atomic c o o r d i n a t e s and temperature f a c t o r s i s presented i n Table XXXIX and a n i s o t r o p i c thermal parameters f o r non-hydrogen atoms are given i n Table XL. Y = r 4 '1+cos 26 2 1+cos 2 6 s i n 2 6 3 V 2 x where V i s t h e volume 12.593 and T i s t h e mean t r a n s m i s s i o n p a t h l e n g t h 159 Table XXXIX F i n a l p o s i t i o n a l ( f r a c t i o n a l x 10 5, H x 10 3) and i s o t r o p i c thermal parameters (U x 10 3 A 2) with estimated standard d e v i a t i o n s i n parentheses Atom X 1 z Ueq/U i s o C(1) 55042(23) 13913(33) 65380(19) 45 C(2) 60655(21) -160(32) 70552(19) 42 C(21 ) 53993(39) -14597(49) 66836(35) 71 C(3) 60690(21) 4181(33) 81383(19) 45 C(31 ) 56373(40) -7121(57) 87757(31) 76 C(4) 64132(22) 18184(35) 84397(20) 46 C(41 ) 64072(42) 24161(63) 94693(28) 78 C(4a) 69955(23) 27705(32) 77830(20) 51 C(4a1 ) 70615(53) 44767(46) 80587(38) 88 C(5) 81862(25) 21046(40) 80195(26) 59 C(6) 81535(21) 4419(36) 77570(20) 49 C(61 ) 88274(32) -5574(61) 83079(31) 79 C(7) 72670(21) 625(32) 68131(19) 44 C(71 ) 75583(38) -13489(49) 6281 5(31 ) 73 C(8) 71454(27) 14881(37) 61453(23) 51 C(8a) 64186(24) 25406(33) 66145(20) 48 C(8a1 ) 60276(53) 39753(49) 60040(36) 85 0 4534 1(16) 15105(25) 60954(15) 70 H1(21 ) 534( 3) -1 57 ( 3) 598( 3) 84( 12) H2(21 ) 576( 3) -241 ( 5) 706( 3) 101 ( 14) H3(21 ) 465( 3) -1 31 ( 4) 675( 3) 97( 14) H1(31 ) 584( 3) -40( 5) 948( 3) 1 18( 14) H2(31) 485( 4) -83( 4) 856( 3) 1 15( 15) H3(31 ) 599( 4) -1 76 ( 6) 873( 4) 1 62 ( 22) H1(41 ) 598( 4) 181 ( 5) 983( 3) 1 43 ( 20) H2(41) 71 1 ( 3) 250( 4) 984( 3) 96( 14) H3(41) 61 4 ( 4) 352( 6) 939( 4) 161 ( 22) H1(4a1) 750( 3) 496( 5) 765( 3) 1 1 8 ( 17) H2(4a1) 625( 4) 503( 5) 800( 3) 1 24 ( 16) H3(4a1 ) 747( 3) 461 ( 4) 875( 3) 88( 11) H1 (5) 853( 2) 229( 3) 876( 2) 58( 8) H2(5) 863( 2) 267( 3) 762( 2) 71 ( 9) H1(61) 936( 3) -24( 3) 893( 2) 79( 10) H2(61) 876( 3) -1 60 ( 4) 8 1 2 ( 2) 77( 12) H1 (71 ) 828( 3) -1 1 2( 4) 6 1 5 ( 3) 1 08 ( 15) H2(71) 700( 3) -151 ( 3) 560( 3) 84( 11) H3(71 ) 759( 3) -235( 4) 669( 3) 1 00 ( 13) H1 (8) 673( 2) 1 22 ( 3) 542( 2) 57( 8) H2(8) 786( 3) 1 93 ( 3) 61 0( 2) 76( 10) H1 (8a1 ) 562( 3) 368( 4) 533( 3) 98( 13) H2(8a1) 668( 3) 462( 5) 598( 3) 1 1 4( 17) H3(8a1) 550( 3) 452( 4) 633( 3) 92( 14) 160 Table XL « F i n a l a n i s o t r o p i c thermal parameters ( U i j x 10" A 2) and t h e i r estimated standard d e v i a t i o n s Atom u, 1 u 2 2 U 3 3 u 1 2 y, 3 y 2 3 C O ) 389( 16) 604(20) 354(15) 7 3 0 6 ) 1 03( 13) -36( 14) C(2) 385( 14) 440(16) 430(15) -40(14) 1 04 ( 11) -15( 14) C(21 ) 781 ( 29) 643(27) 709(28) -228(23) 1 66 ( 22) -1 19( 22) C(3) 359( 15) 569(21) 428(16) -11(14) 1 29( 12) 43( 15) C(31 ) 743( 28) 982(34) 593(25) -219(26) 254( 21 ) 1 27 ( 23) C(4) 436( 16) 577(20) 370(15) 43(15) 83( 12) -1 6( 14) C(41 ) 859( 30) 989(36) 468(20) -15(28)- 1 42 ( 21 ) -1 57 ( 23) C(4a) 570( 19) 418(18) 51307) -4605) 62< 14) -27( 15) C(4a1 ) 1 287( 43) 519(25) 755(30) -130(27) 81 ( 30) -1 23 ( 21) C(5) 462( 19) 768(27) 511(20) -172(18) 57< 15) 47( 19) C(6) 323( 15) 692(23) 487(17) 57(15) 141 13) 1 06 ( 16) C(61 ) 631 ( 24) 1009(37) 676(25) 210(25) 58 19) 1 1 2( 26) C(7) 41 4( 15) 490(18) 424(15) 72(14) 1 39 12) 24( 15) C(71 ) 771 ( 28) 755(29) 690(26) 265(24) 235 22) -51 ( 23) C(8) 452( 17) 657(22) 440(18) -27(17) 1 50 14) 67( 16) C(8a) 573( 18) 428(17) 435(16) 52(15) 85 14) 92( 14) C(8a1 ) 1 1 86 ( 40) 590(26) 681(27) 147(29) 60 f28) 1 56( 22) 0 399( 13) 1040(19) 605(14) 167(12) 9 [10) -71 ( 12) 161 D i s c u s s i o n The s t r u c t u r e c o n s i s t s of molecules composed of a t w i s t e d h a l f - c h a i r cyclohexenone r i n g c i s - f u s e d to a t w i s t e d boat cyclohexane moiety. In a d d i t i o n t o the b r i d g i n g bond C(4a)- C ( 8 a ) 1 , the two six-membered r i n g s are j o i n e d v i a atoms C(2) and C(7) forming a five-membered r i n g with atoms C ( l ) , C(8a) and C(8) (see F i g u r e 25, page 171). The molecule i s h i g h l y s t r a i n e d , as evidenced by marked d e v i a t i o n s from the expected values of angles a s s o c i a t e d with atoms of given h y b r i d i z a t i o n s (Tables XLI and X L I I ) . The e n d o c y c l i c angles of the five-membered r i n g which i n c l u d e s a f o r m a l l y s p 2 - h y b r i d i z e d carbon atom, range from 94° to 105°; the experimental value f o r the angles of u n s u b s t i t u t e d cyclopentane i s 111.7° (54) and f o r p l a n a r aromatic c y c l o p e n t a d i e n y l i s 108°. F u r t h e r angular s t r a i n i s n o t i c e a b l e i n those angles c o n t a i n i n g methyl groups. Each methyl s u b s t i t u e n t i s e c l i p s e d with at l e a s t one other methyl group on an adjacent carbon. Except f o r C(31)-C(3)-C(2)-C(21) (11.5(3)°) and C(41)-C(4)-C(4a)-C(4a1) (-24.4(4)°), H 3 C - C - O C H 3 t o r s i o n angles range from -1.2(3) to -2.9(4) (Table X L I I I ) . The s t e r i c r e p u l s i o n of the e c l i p s e d s u b s t i t u e n t s r e s u l t s i n widening the H 3C-C-C angles by as much as 7.4° i n the case of C(8a1)-C(8a)- C(4a); the combined e f f e c t at the bridgeheads i s a net i n c r e a s e of 8.5°. The o v e r a l l s t r e s s i n the molecule i s a l l e v i a t e d somewhat by the lengthening of the b r i d g i n g bonds C(4a)-C(8a) and C ( 2 ) - 1 Note, atom l a b e l s r e f e r to the same system used i n naming the naphthoquinol p r o g e n i t o r ( V I I I ) . Table XLI Bond angles (°) with estimated standard d e v i a t i o n s i n parentheses; pected v a l u e s are en c l o s e d i n brack e t s C ( s p 3 ) - C ( s p 3 ) - C ( s p 3 ) [109 .5] C(21 ) -C(2) -C(7) 114. 7(3) C(4a1) -C(4a) -C(5) 108. 9(3) C(4a1) -C(4a) -C(8a) 110. 6(3) C(5) -C(4a) -C(8a) 109. 5(2) C(2) -C(7) -C(71) 113. 8(3) C(2) -C(7) -C(8) 101. 4(2) C(71 ) -C(7) -C(8) 112. 0(3) C(7) -C(8) -C(8a) 102. 8(2) C(4a) -C(8a) -C(8) 109. 4(2) C(4a) -C(8a) - C ( 8 a 1 ) 116. 9(3) C(8) -C(8a) -C(8a1) 113. 9(3) C ( s p 3 ) - C ( s p 3 ) - C ( s p 2 ) [109 '.5] C(21 ) -C(2) -CO) . 111. 8(3) C(21 ) -C(2) -C(3) 113. 8(3) C(7) -C(2) -C(1 ) 102. 2(2) C(7) -C(2) -C(3) 1 14. 0(2) C(4a1) -C(4a) -C(4) 112. 9(3) C(5) -C(4a) -C(4) 103. 3(2) C(8a) -C(4a) -C(4) 111. 3(2) C(4a) -C(5) -C(6) 110. 4(2) C(2) -C(7) -C(6) 110. 3(2) C(71 ) -C(7) -C(6) 112. 4(3) C(8) -C(7) -C(6) 1 06. 1 (2) C(4a) -C(8a) -CO ) 1 07. 4(2) C(8) -C(8a) -C(1 ) 94. 3(2) C(8a1) -C(8a) -c(D 112. 5(3) C ( s p 2 ) - C ( s p 3 ) - C ( s p 2 ) C O ) -C(2) -C(3) [109.5] 98.4(2) Table XLI (continued) X ( S P 2 ) - C ( s p 2 ) - C ( s p 3 ) [120 .0] 0 -CO ) -C(2) 1 26. 5(3) 0 -CO) -C(Ba) 128. 0(3) C(2) - c o ) -C(8a) 105. 3(2) C(4) -C(3) -C(2) 117. 1(2) C(4) -C(3) -C(31) 123. 9(3) C(3) -C(4) -C(41) 122. 5(3) C(3) -C(4) -C(4a) 118. 7(2) C ( s p 3 ) - C ( s p 2 ) - C ( s p 3 ) [120 .0] C(2) -CO ) -C(8a) 1 05. 3(2) C(2) -C(3) -C(31) 118. 9(3) C(41 ) -C(4) -C(4a) 118. 2(3) C(5) -C(6) -C(61) 1 22. 2(3) C(5) -C(6) -C(7) 113. 0(2) C(61 ) -C(6) -C(7) 124. 8(3) 164 Table XLII Bond angles (deg) i n v o l v i n g hydrogen atoms with estimated standard d e v i a t i o n s i n parentheses Bonds Angle Bonds Angle C(2) -C(21) -H1(21) 109(2) C(4a) -C(5) -H1(5) 107(2) C(2) -C(21) -H2(21) 112(2) C(4a) -C(5) -H2(5) 109(2) C(2) -C(21) -H3(21) 108(2) C(6) -C(5) -H1(5) 1 12(2) H1 (21 ) -C(21) -H2(21) 110(3) C(6) -C(5) -H2(5) 109(2) H1(21 ) -C(21) -H3(21) 105(3) H1 (5) -C(5) -H2(5) 109(2) H2(21) -C(21) -H3(21) 112(3) C(6) -C(61) -H1(61) 121(2) C(3) -C(31) -H1(31) 110(2) C(6) -C(61) -H2-(61 ) 119(2) • C(3) -C(31) -H2(31) 111(2) H1(61 ) -C(61) -H2(61) 120(3) C(3) -C(31) -H3(31) 110(3) C(7) -C(71) -H1(71) 105(2) H1(31 ) -C(31) -H2(31) 110(3) C(7) -C(71)- -H2(71) 111(2) H1(31 ) -C(31) -H3(31) 108(4) C(7) -C(71) -H3(71) 115(2) H2(31 ) -C(31) -H3(31) 108(4) H1(71 ) -C(71) -H2(71 ) 108(3) C(4) -C(41) -H1(41) 115(3) H1(71 ) -C(71) -H3(71) 1 10(3) C(4) -C(41) -H2(41) 110(2) H2(71) -C(71) -H3(71) 108(3) C(4) -C(41) -H3(41) 108(3) C(7) -C(8) -H1(8) 110(2) H1 (41 ) -C(41) -H2(41) 109(3) C(7) -C(8) -H2(8) 113(2) H1 (41 ) -C(41) -H3(41) 112(4) H1 (8) -C(8) -H2(8) 106(2) H2(41) -C(41) -H3(41) 103(3) C(8a) -C(8a1) -H1(8a1) 109(2) C(4a) -C(4a1 )-H1(4a1) 106(2) C(8a) -C(8a1) -H2(8a1) 1 10(2) C(4a) -C(4a1 )-H2(4a1) 115(2) C(8a) -C(8a1) -H3(8a1) 107(2) C(4a) -C(4a1 )-H3(4a1) 110(2) H I ( 8 a 1 ) - C ( 8 a 1 ) - H 2 ( 8 a 1 ) 1 1 1 ( 3 ) H1(4a1)-C(4a1)-H2(4a1)113(3) HI(8a1)-C(8a1)-H3(8a1)108(3) H1(4a1)-C(4a1)-H3(4a1)107(3) H2(8a1)-C(8a1)-H3(8a1)112(3) H2(4a1)-C(4a1)-H3(4a1)106(3) Table XLIII T o r s i o n angles (deg) wi t h estimated standard d e v i a t i o n s i n parentheses Atoms Value C(8a) -c( 1) -c( 2) -C(21) -156.0( 3) C(8a) -c( 1) -c( 2) -C(3) 84.1 ( 2) 0 -c( 1) -c( 2) -C(21) 19.2( 4) 0 -c( 1) -c( 2) -C(3) -100.7( 3) C(2) -c( 1) -c( 8a) -C(4a) -57.8( 3) C(2) -c( 1) -c( 8a) -C(8a1) 172.2( 3) 0 -c( 1) -c( 8a) -C(4a) 127.1( 3) 0 -c( 1) -c( 8a) -C(8a1) -2.91 4) C O ) -c( 2) -c( 3) -C(31 ) 129.91 3) C O ) -c( 2) -c( 3) -C(4) -47.1 I 3) C(21 ) -c( 2) -c( 3) -C(31) 11.51 4) C(21 ) -c( 2) -c( 3) -C(4) -165.51 3) C(2) -c( 3) -c( 4) -C(41) 177.1 I 3) C(2) -c( 3) -CI 4) -C(.4a) . -12...2 I 3) C(31 ) -c( 3) -C( 4) -C(41) TJ.2I 5) C ( 3 1 ) -C( 3) -c( 4) -C(4a) 1 70.91 3) C(3) -c( 4) -CI 4a) -C(4a1) 164.5 3) C(3) -c( 4) -c< 4a) -C(5) -78.0 3) C(3) -C( 4) -c< 4a) -C(8a) 39.4 3) C(4I) -c< 4) -CI 4a) -C(4a1) -24.4 i4) C(41 ) -C( 4) -CI 4a) -C(5) 93. 1 (3) C(41 ) -CI 4) -c 4a) -C(8a) -149.5 (3) C(4) -CI 4a) -c ,5) -C(6) 59.9 (3) C(4a1 )-c< 4a) -c ,5) -C(6) -179.8 (3) C(8a) -c< ,4a) -c (5) -C(6) -58.7 (3) C(4) -c (4a) -CI (8a) -CO ) -2.4 (3) C(4) -c (4a) -c (8a) -C(8a1) 125. 1 (4) C(4a1 )-c [4a) -c (8a) -CO ) -128.7 (3) C(4a1 )-c !4a) -c (8a) -C(8a1) -1 .2 (5) C(5) -c (4a) -c (8a) -CO ) 111.2 (3) C(5) -c (4a) -c (8a) -C(8a1) -121.3 (4) C(4a) -c (5) -c (6) -C(61) -142.2 (3) C(4a) -c (5) -c (6) -C(7) 37.2 (3) C(5) -c (6) -c (7) -C(7 1) 1 53.2 (3) C(5) -c (6) -c (7) -C(8) 30.5 (3) C(61 ) -c (6) -c (7) -C(71) -27.4 (4) C(61 ) -c (6) -c (7) -C(8) -150.1 (3) C O ) -c (2) -c (21) -H1(21) 61 (2 C O ) -c (2) -c (21) -H2(21) -177(2 CO ) -c (2) -c (21 ) -H3(21) -53(2 C(3) -c (2) -c (21) -H1(21) 171 (2 C(3) -c (2) -c (21) -H2(21) -67(2 C(3) -c (2) -c (21 ) -H3(21) 57(2 C(2) -c (3) -c (31 ) -H1(31) 167(2 Table XLIII (continued) C(2) -c( 3) -C(31) -H2( 31 ) -71(3) C(2) -c( 3) -C(31) -H3( 31 ) 49(3) C(4) ~C( 3) -C(31) -H1 ( 31 ) -16(3) C(4) -c( 3) -C(31) -H2( 31 ) 106(3) C(4) -c( 3) -C(31) -H3( 31 ) C(3) -c( 4) -C(41) -H1 ( 41 ) -14(3 C(3) -c( 4) -C(41) -H2( 41 ) 109(3 C(3) rC( 4) -C(41) -H3( 41 ) -139(3 C(4a) -c( 4) -C(41) -H1 ( 41 ) 176(3 C(4a) -c( 4) -C(41) -H2( 41 ) -62(3 C(4a) -c( 4) -C(41) -H3( 41 ) 50(3 C(4) -c( 4a) -C(4a1) -H1 ( 4a 1 ) 175(3 C(4) -c( 4a) -C(4a1) -H2( 4a 1 ) -60(2 C(4) -c( 4a) -C(4a1) -H3( 4a 1 ) 60(2 C(5) -c( 4a) -C(4a1) -H1 ( 4a 1 ) 61(3 C(5) -c( 4a) -C(4a1) -H2I 4a 1 ) -1 74(2 C(5) -c( 4a) -C(4a1) -H3I 4a 1 ) -54(2 C(8a) -c( 4a) -C(4a1) -H1 I 4a 1 ) -60(3 C(8a) -c< 4a) -C(4a1) -H2I 4a 1 ) 66(2 C(8a) -c< 4a) -C(4a1) -H3I 4a 1 ) -175(2 C(4) -CI 4a) -C(5) -H1 I 5) -63(2 C(4) -c< 4a) -C(5) -H2 5) -180(2 C(4a1) -c 4a) -C(5) -H1 ,5) 58(2 C(4a1 ) -c 4a) -C(5) -H2 [5) -60(2 C(8a) -c 4a) -C(5) -H1 (5) 179(2 C(8a) -c [4a) -C(5) -H2 (5) 61 (2 H1 (5) -c (5) -C(6) -C(61) -23(2 H1 (5) -c (5) -C(6) -C(7) 1 57(2 H2(5) -c (5) -C(6) -C(61) 98(2 H2(5) -c (5) -C(6) -C(7) -83(2 C(5) -c (6) -C(61) -H1 (61 ) 3(2 C(5) -c (6) -C(61) -H2 (61 ) 178(2 C(7) -c (6) -C(61) -H1 (61 ) -177(2 C(7) -c (6) -C(61) -H2 (61 ) -1 (2 C(6) -c (7) -C(71) -H1 (71 ) -57(2 C(6) -c (7) -C(71) -H2 (71 ) -173(2 C(6) -c (7) -C(71) -H3 (71 ) 65(2 C(8) -c (7) -C(71) -H1 (71 ) 63(2 C(8) -c (7) -C(71) -H2 (71 ) -53(2 C(8) -c (7) -C(71) -H3 (71 ) -176(2 C(6) -c (7) -C(8) -HI (8) 1 64.3 C(6) -c (7) -C(8) -H2 (8) 45(2 C(71 ) -c (7) -C(8) -H1 (8) 41 (2 C(71) -c (7) -C(8) -H2 (8) -78(2 C(1) -c (8a) -C(8a1) -H1 (8a1 ) -48(2 C(1) -c (8a) -C(8a1) -H2 (8a1 ) -170(2 C(1 ) -c (8a) -C(8a1) -H3 (8a1 ) 68(2 C(4a) -c (8a) -C(8a1) -H1 (8a1 ) -173(2 C(4a) -c (8a) -C(8a1) -H2 (8a1 ) 65(3 C(4a) -c (8a) -C(8a1) -H3 (8a1 ) -57(2 167 C(7) to d i s t a n c e s of 1.604(4) and 1.602(4) A, r e s p e c t i v e l y (Table XLIV). T h i s i n c r e a s e i n l e n g t h of approximately 0.07 A over accepted values (33) f o r C ( s p 3 ) - C ( s p 3 ) bonds i s not enough to e l i m i n a t e the r e p u l s i v e e f f e c t of the e c l i p s e d methyls (vide s u p r a ) . The s t r a i n induced i n the cyclohexenone r i n g on bonding C(2) to C(7) i s compensated somewhat by the s t r e t c h i n g of the br i d g e C(4a)-C(8a); i n a d d i t i o n , bonds C(2)-C(3) and C(4a)-C(4) show i n c r e a s e s as w e l l , a veraging 0.024 A g r e a t e r than the accepted value of 1.510 A f o r C ( s p 3 ) - C ( s p 2 ) . Other bonds w i t h i n the s t r u c t u r e (Table XLV) do not d e v i a t e s i g n i f i c a n t l y from accepted v a l u e s . I n t e r m o l e c u l a r c o n t a c t s g e n e r a l l y correspond to van der Waals d i s t a n c e s . The photochemical r e a c t i o n , i l l u s t r a t e d i n F i g u r e 24, i n v o l v e s a s h i f t i n the secondary bridge from C(4)-C(7) to C(2)- C ( 7 ) . The r e a c t a n t energy, r e l a t i v e to the product, i s not e a s i l y deduced from' t h i s study, but D r e i d i n g models of both molecules suggest that (IX) i s the higher energy isomer m a n i f e s t i n g two very s t r a i n e d five-membered r i n g s as opposed to only one of these r i n g s i n (X). I t i s i n t e r e s t i n g to note that molecular mechanics c a l c u l a t i o n s (47) on the unsaturated, u n s u b s t i t u t e d t r i c y c l o analogs of (IX) and (X) i n d i c a t e s t r a i n s of 23.59 and 30.90 kcal/mole, r e s p e c t i v e l y . The e f f e c t of adding s u b s t i t u e n t s and s p 2 - h y b r i d i z e d r i n g members i s l i k e l y to i n c r e a s e the energy of both molecules but even the r e l a t i v e magnitudes of the i n c r e a s e s would be d i f f i c u l t to p r e d i c t . However, a l e s s than r i g o r o u s comparison of conformations tends to c o n f i r m the molecular mechanics i n d i c a t i o n of (X) as the 168 Table XLIV Bond l e n g t h s (A) with standard d e v i a t i o n s i n parentheses; accepted v a l u e s 2 are e n c l o s e d i n brac k e t s Bond Length C ( s p 3 ) - C ( s p 3 ) [1.537(5)] C(2) -C(21) 1 .530(4) C(2) -C(7) 1.602(4) C(4a) -C(4a1) 1.541(5) C(4a) -C(5) 1.544(4) C(4a) -C(8a) 1.604(4) C(7) -C(71) 1.524(5) C(7) -C(8) 1.537(4) C(8) -C(8a) 1.536(6) C(8a) -C(8a1) 1.525(5) C ( s p 3 ) - C ( s p 2 ) [1.510(5)] C(2) -CO ) 1.507(4) C(8a) -CO ) 1 .500(4) C(2) -C(3) 1.535(4) C(31 ) -C(3) 1.504(4) C(41 ) -C(4) 1.511(4) C(4a) -C(4) 1.532(4) C(5) -C(6) 1.500(5) C(7) -C(6) 1.519(4) C ( s p 2 ) - C ( s p 2 ) [1 .335(5)] C(3) -C(4) 1.333(4) C(6) -C(61) 1.316(6) C ( s p 2 ) -0 [1.215(5)] C(1 ) -0 1.212(3) 2 From r e f e r e n c e 33. . Table XLV Bond lengths i n v o l v i n g hydrogen atoms (A) with estimated standard d e v i a t i o n s i n parentheses Bond Length C(21 ) -H1(21) 0 .95(4) C(21 ) -H2(21) 1 .03(4) C(21 ) -H3(21) 0 .97(4) C(31 ) -H1(31) 0 .97(4) C(31 ) -H2(31) 0 .95(4) C(31 ) -H3(31) •1 .02(5) C(41 ) -H1(41) 0 .97(5) C(41 ) -H2(41) 0 .90(3) C(41 ) -H3(41) 1 .02(5) C(4a1 )-H1(4a1 ) 0 .97(4) C(4a1 )-H2(4a1 ) 1 .10(4) C(4a1 )-H3(4a1 ) 0 .98(3) Bond Length C(5) -H1(5) 1 . 0 1 ( 3 ) C(5) - H 2 ( 5 ) 1 . 0 0 ( 3 ) C(61 ) - H 1(61) 0 .99 (3 ) C(61 ) - H 2(61) 0 .95 (3 ) C(71 ) - H 1(71) 0 .98(4) C(71 ) - H 2(71) 1 .04(4) C(71 ) - H 3(71) 1 .04(4) C(8) - H 1 ( 8 ) 1 .03 (3 ) C(8) - H 2 ( 8 ) 0 .98 (3 ) C ( 8 a 1 ) - H 1 ( 8 a 1 ) 0 .97(4) C ( 8 a 1 ) - H 2 ( 8 a 1 ) 0 .99(4) C ( 8 a 1 ) - H 3 ( 8 a 1 ) 1 . 0 0 ( 4 ) 170 higher energy isomer: (IX) k c a l (X) 1) conformation of the i ) boat six-membered r i n g s 2 > t w i s t e d boat i i ) h a l f - c h a i r 3 > t w i s t e d half- c h a i r 2) s t e r e o c h e m i s t r y of s u b s t i t u e n t s a l l are at r e l a t i v e l y l e a s t energy p o s i t i o n s < 10 two p a i r s of methyls are e c l i p s e d ; a x i a l hydrogens on C(5) and C(8) are in c l o s e p r o x i m i t y The i n d i c a t i o n i s that from molecular s t r a i n and s t e r i c arguments alone, (X) i s approximately 5 k c a l higher i n energy than i t s p r e c u r s o r ( I X ) . T h i s i s i n c o n t r a s t to the D r e i d i n g model sug g e s t i o n . Although such models n i c e l y i l l u s t r a t e t o r s i o n a l and angular s t r a i n , they are l e s s e f f e c t i v e i n show