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Exploratory organic photochemistry : internal epoxy ketones and medium sized dienes Gayler , Rudolf Erich 1971

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EXPLORATORY ORGANIC PHOTOCHEMISTRY. INTERNAL EPOXY KETONES AND MEDIUM SIZED RING DIENES BY RUDOLF ERICH GAYLER D i p l . Chem. ETH, Zurich, 1968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of CHEMISTRY We accept t h i s t h e s i s as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA May, 1971 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. V Depa rtment The University of British Columbia Vancouver 8, Canada - i i -ABSTRACT In Part I of this work octahydro-4a,8a-epoxy-l(2H.)-naphthalenone, hexahydro-3a,6a-epoxy-l(2H)-pentalenone,and octahydro-3a,8a-epoxy-4(lH)-azulenone were photolyzed. The major course of these reactions was one of polymerization. Small amounts of monomeric products could however be obtained with d i f f i c u l t y and were tentatively assigned the structures which arise mechanistically via the same path as in the rearrangement of ordinary aliphatic a,B-epoxy ketones i.e, 1,3-diketone formation. In order to prove the structure of the photoproduct of the naphthalenone epoxide the synthesis of 2-cyclopentylidene-cyclopentanone oxide was attempted. In Part II of this thesis the nature of the excited state in the photolysis of cis,cis-cyclodeca-3,8-diene-l,6-dione was investigated by quenching and sensitization experiments. These suggested that the reactive excited state involved was a highly reactive t r i p l e t state. Furthermore, the thermal reaction of cis,trans-cyclodeca-3,8-diene-1,6-dione was investigated and found to give rise to three new products in low yields whose structures are s t i l l under investigation. They probably arose from an ene-reaction. Thermolysis of cis,cis-cyclodeca-3,8-diene-1,6-dione afforded 3a,5,8,8a-tetrahydro-8a-hydroxy-4(IH)-azulenone. A low temperature photolysis of cis,trans-cyclodeca-3,8-diene-l,6-dione was carried out at 77°K in order to trap the potential intermediate trans,trans-cyclodeca-3,8-diene-l,6-dione. However, besides a minor amount of cis,cis-isomer, the low temperature photolysis afforded the same product as that obtained by photolysis at ambient temperature. - i i i -F i n a l l y the centrosymmetric a n t i - c o n f i g u r a t i o n of the t r i c y c l i c photo-product from cis,cis-cyclodeca-3,8-diene-l,6-dione was furt h e r supported by a dipole measurement and by i n f r a r e d and Raman spectroscopy. - iv -TABLE OF CONTENTS Page PART I PHOTOCHEMISTRY OF INTERNAL a,6-EP0XY KETONES 1 INTRODUCTION 2 A. Background of Epoxy Ketone Photochemistry 2 B. Objectives of Present Research 9 RESULTS AND DISCUSSION 12 A. Hexahydro-3a,6a-epoxy-l(2H)-pentalenone 12 B. Octahydro-4a,8a-epoxy-l(2H)-naphthalenone 15 C. 2-Cyclopentylidene-cyclopentanone Oxide 16 D. Octahydro-3a,8a-epoxy-4(lH)-azulenone 24 SUMMARY 27 PART II THERMAL AND PHOTOCHEMICAL PROPERTIES OF CIS,CIS-CYCLODECA-3,8-DIENE-l,6-DIONE 28 INTRODUCTION 29 A. Intramolecular Photochemical Cycloadditions of Non-conjugated Dienes 29 B. Earlier Results of the Photochemistry of 1,6-Cyclo-decadiene Systems 35 C. Previous Results of the Photochemistry of c i s , c i s -Cyclodeca-3,8-diene-l,6-dione 36 D. Objectives of Present Research 39 RESULTS AND DISCUSSION 41 Page A. The Nature of the Excited State in the Photolysis of cis,cis-Cyclodeca-3,8-diene-l,6-dione 41 B. Thermolysis of cis,trans-Cyclodeca-3,8-diene-l,6-dione 42 C. Thermolysis of cis,cis-Cyclodeca-3,8-diene-l 56-dione 45 D. Low Temperature Photolysis of cis,trans-Cyclodeca-3,8-diene-l,6-dione 48 2 6 E. Configuration of Tricyclo[5.3.0.0 ' ]deca-4,9-dione 50 (a) Dipole Moment 50 (b) Vibrational Spectroscopy 52 EXPERIMENTAL 54 BIBLIOGRAPHY 70 - v i -ACKNOWLEDGEMENTS I would l i k e to thank Dr. J.R. Scheffer f o r h i s continual advice and encouragement throughout t h i s work. I am also g r a t e f u l to my fellow graduate students f o r many h e l p f u l discussions and f o r t h e i r c o r d i a l s p i r i t . I am further indebted to the many s t a f f members of t h i s department f o r t h e i r contributions and to the U n i v e r s i t y f o r a Teaching A s s i s t a n t s h i p . Last but not l e a s t I would l i k e to thank my wife Barbara f o r her help and support. PART I PHOTOCHEMISTRY OF INTERNAL a,g-EPOXY KETONES - 2 -INTRODUCTION A. Background of Epoxy Ketone Photochemistry A l i p h a t i c and a l i c y c l i c a,B-epoxy ketones rearrange to 1,3-diketones upon u l t r a v i o l e t i r r a d i a t i o n . As shown i n eq 1, one of the 8-substituents migrates to the a - p o s i t i o n . The f i r s t r e a c t i o n of 0 . 0 0 R' 0 II / \ hv 11 1 11 R-C-C — C-R' — — • R-C-C-C-R (1) I I l R R' R t h i s type was reported by Bedforss i n 1918."'' He observed the l i g h t -induced rearrangement of benzalacetophenone epoxide (3) to the corres-ponding 1,3-diketone 4 (eq 2). The mechanism of t h i s rearrangement was 0 0 II / \ A-C-CH—CH I hv 0 II 0 II <j>-C-CH2-C-<j> (2) not investigated u n t i l 1963 when Zimmerman and Reusch independently 2 published a s e r i e s of experiments which l e d them to the same conclusions. ' Zimmerman found that i n the photolysis of _5 only the methyl group migrated. - 3 -0 0 0 0 ll / \ h v ii II CH.-C-CH—C-CH„ — >• CH.-C-CH-C-* (3) 3 I 3 3 j * CH 3 Markos and Reusch found the following order of migratory aptitudes for 4 d i f f e r e n t substituents: benzyl > hydrogen > methylene > methyl >> phenyl. An i o n i c mechanism could be ruled out since t h i s would favor the 1,2-s h i f t of the phenyl and not of the methyl group. Thus the p o s s i b i l i t y of a r a d i c a l mechanism was inv e s t i g a t e d . Free r a d i c a l s show much less tendency to undergo rearrangement than do more e l e c t r o n d e f i c i e n t species. Nevertheless 1,2-phenyl s h i f t s have been observed. However, 1,2-alkyl or hydrogen s h i f t s of free r a d i c a l s are very rare."' Where there i s a choice between phenyl and a l k y l migration, phenyl migration takes place e x c l u s i v e l y . This was confirmed by molecular o r b i t a l c a l c u -6 l a t i o n s by Zimmerman and Zweig. The energy d i f f e r e n c e s found f o r 1,2-shifts of phenyl vs. methyl are shown i n eq 4 and 5. CH_ CH 3 I 3 /v Ph-fJ — C- Ph-C—C- AE = - 0.450 (4) CH. CH„ Ph-C — C - >• C^rJcf AE = - 0.853 (5) I I / \ / \ ^h However, two r a d i c a l reactions have been reported where methyl expulsion or migration i s favored over phenyl expulsion or migration. The f i r s t one by Kharash and coworkers deals with the thermal decomposition of hydroperoxide ]_ which gives alkoxy r a d i c a l 8^ .^  The l a t t e r e j e c t s only - 4 -PhC(CH 3) 2OOH PhC(CH 3) 20- —>• PhCOCH3 + • CH 3 (6) 1 JL i CH 3COCH 3 + Ph-methyl r a d i c a l s which pick up a hydrogen from the solvent to form methane. I f a phenyl r a d i c a l would have been ejected,the product formed would have been acetone which was not observed. g The second example was reported by Greene and coworkers. The thermal decomposition of peroxylactone 9_ showed a f i v e - f o l d preference f o r the product where the methyl group had migrated. 0 -> PhCOCH 2CH 3 + PhCH 2COCH 3 10 (70%) 11 (15%) / (7) CH2* Ph -0. + c o 2 CH 3 13 12 0 0 0' 0 0 0 / \ II hv 1 • *l » H Ph-C — C-C-CH. Ph-C-CH-C-CH„ y PhC-CH-C-CH„ (8) I J I i. -1 CH 3 CH 3 CH 3 14 15 16 - 5 The postulated intermediate L3 i s analogous to the intermediate 2 15 put forward by Zimmerman. However, intermediate L5_ should have a very short l i f e t i m e since i t has been shown that the carbon a to the carbonyl group re t a i n s i t s stereochemistry as i n the photolysis of 17. hv ?*0 (9) 17 18 The v a l i d i t y of comparing intermediates 13 and L5 obtained by a thermal and a photochemical r e a c t i o n finds support by the f a c t that thermolysis of pulegone oxides 19a or 19b i n the l i q u i d phase gives 3 10 r i s e to the same products 20a and 20b as does photolysis (eq 10). ' 19a 19b a-oxide 3-oxide hv or A (10) 20a cis-methyl groups 20b trans-methyl groups - 6 -0 0' o 21 22 However, t h e r m o l y s i s of other epoxy ketones such as 21_ and 22_ does not r e s u l t i n t h i s k i n d of behavior. Nevertheless the pulegone oxide chemistry opens the p o s s i b i l i t y t h a t the photochemical r e a c t i o n proceeds by way of a v i b r a t i o n a l l y e x c i t e d s p e c i e s . Another p o i n t of i n t e r e s t i n the mechanism of the epoxy ketone rearrangement was the question whether the m i g r a t i o n of the s u b s t i t u e n t was concerted or stepwise. The l a t t e r mechanism would i n v o l v e a more or l e s s f r e e r a d i c a l m i g r a t i n g to the neighbouring carbon r a d i c a l s i t e . As Reusch p o i n t e d out, the p r e f e r e n t i a l m i g r a t i o n of hydrogen over methyl speaks against a fragmentation process s i n c e hydrogen atoms are 4 not normally formed i n preference to methyl r a d i c a l s . Further evidence along the same l i n e comes from an i n v e s t i g a t i o n by Schaffner and coworkers."''''' They found that i n s t e r o i d a l epoxy ketones such as 2 3 , the stereochemistry at C ^ Q was preserved (eq 1 1 ) . From t h i s i t was concluded that the rearrangement of 23_ to 15. w a s e i t h e r concerted or at l e a s t so f a s t that i n the t r a n s i t i o n s t a t e 2b_, would not have time to epimerize. S t e r i c a l l y , continuous overlap between breaking and forming bonds i s p o s s i b l e . The p h o t o l y s i s of s t e r o i d 2_7 - 7 -( I D H 26 represents an i n t e r e s t i n g case where two products would be expected i f the r e a c t i o n would be non-concerted. However, only one product, 30 11a i s observed. The formation of j30_ can occur with continuous overlap whereas the path leading to 32^ involves r o t a t i o n about two s i n g l e bonds, marked by arrows i n _31_, and would therefore i n t e r r u p t the overlap. This i s the argument put forward to account for the s e l e c t i v i t y of the r e a c t i o n . In contrast to these examples favoring a concerted r e a c t i o n stands 4 the photolysis of _33_. Here a substituent i s migrating which can form PhCH n^n 0 S<1 0 0 hv + PhCH 2CH 2Ph (12) '0 33 34 (20%) 35 + other fragmentation products a very stable r a d i c a l . From the formed dibenzyl i t has to be concluded that some of the migrating benzyl groups escape the solvent cage and combine to give dibenzyl. Thus, the degree of concertedness seems to depend on the s t a b i l i t y of the r a d i c a l of the migrating substituent. The nature of the excited state involved i n the photochemical rearrangement of epoxy ketones was found to be a s i n g l e t state on the basis of s e n s i t i z a t i o n and quenching experiments c a r r i e d out with four 4 d i f f e r e n t epoxy ketones. B. Objectives of Present Research Up to the present time, the photochemistry of " i n t e r n a l " a, 3-. epoxy ketones such as _3J3, has not been reported. I t seemed i n t e r e s t i n g to study t h e i r photochemistry, since, i f they reacted as other epoxy ketones, they would give s p i r o compounds _37 or _38 or both of them. No preference for path (a) or fo) can be found on the basis of migratory aptitudes since i n both cases a methylene group i s migrating. Other - 10 -(13) 36 • • . 37 (14) new reactions might also take place of course. The i n i t i a l step might be carbon-carbon bond cleavage of the epoxy bond although i t 1 has been shown f o r s t e r o i d a l epoxy ketones that t h i s does not occur. Another p o s s i b i l i t y would be that the migrating group would j o i n with the carbonyl oxygen to give c y c l i c v i n y l ethers 39_ and 40_ as i s shown i n eq 15. The photolysis of " i n t e r n a l " epoxy ketones i n a d d i t i o n to being s i g n i f i c a n t from a photochemical point of view might provide a convenient synthesis of spiroketones. P a r t i c u l a r l y spiroketones of the type _37_ would be of i n t e r e s t since spiroconjugative e f f e c t s could 12 be studied with these ketones and d e r i v a t i v e s therefrom. - 12 -RESULTS AND DISCUSSION A. Hexahydro-3a,6a-epoxy-l(2H)-pentalenone (42) The f i r s t i n t e r n a l epoxy ketone chosen f o r study was 42. I t was synthesized from tetrahydropentalenone 41 (obtained as a g i f t from BASF) by a l k a l i n e epoxidation with hydrogen peroxide i n 68% y i e l d . (16) 41 42 If hl_ would undergo the usual photochemical rearrangement of a,0-epoxy ketones, two products 43_ and ^44_ would be expected. 0 (17) Compound 4_2 was photolyzed i n benzene using a Pyrex f i l t e r and a medium' pressure mercury lamp. The r e a c t i o n was followed by glpc. Four major products, A, B, C, and D, i n order.of i n c r e a s i n g glpc r e t e n t i o n time were formed. They were i s o l a t e d by glpc i n the following y i e l d s : A, 1%; B, 1%; C, 5%; D, 1.5%. Although the s t a r t i n g m a t e r i a l had almost completely reacted no other s i g n i f i c a n t products could be observed by glpc. Thin layer chromatography showed a longish spot at the bottom of the p l a t e , the kind of spot usually observed i f polymeric compounds are present. The i r spectrum of the major product (C) shows two carbonyl bands of equal i n t e n s i t y at 5.57 and 5.75 u. The l a t t e r band corresponds to 13 a five-membered r i n g ketone and the 5.57 y band i s close to the usual p o s i t i o n of the carbonyl band of four-membered r i n g ketones at 5.62 u. Thus the i r spectrum points to structure 43^  f o r C. The s h i f t to shorter wavelengths of the 5.57 y band compared to the usual 5.62 y band f o r cyclobutanones may be caused by mutual i n t e r a c t i o n of the two carbonyl groups. This phenomenon has been observed i n the spectrum of spirodiketone 45_ which shows two carbonyl bands at 5.81 14 and 5.68 u. Although the two tr-orbitals are perpendicular to each 0 45 46 - 14 -other they are close enough (see structure 46) f o r mutual i n t e r a c t i o n . This can be seen i n the uv spectrum of 45_ which shows an enhanced e x t i n c t i o n c o e f f i c i e n t of 100 at 310 nm. The e x t i n c t i o n c o e f f i c i e n t f o r the same s p i r o compound with only one carbonyl function i s about three times smaller.*"' The nmr spectrum of C shows a m u l t i p l e t at 7.36 T i n t e g r a t i n g to s i x hydrogens and a m u l t i p l e t from 7.7-8.3 x i n t e g r a t i n g to four hydrogens. On the basis of the nmr data i t i s hard to d i s t i n g u i s h between structures 43 and 44 f o r C. However, the symmetric structure 44 might have been expected to give a simpler looking spectrum. A complete st r u c t u r e determination of C would require a more s u b s t a n t i a l amount of i t which could then be degradated f o r example by means of an aqueous base. Spiro-l,3-diketones of the type 4-3 and are very base l a b i l e . For example, the structure of 47 has been proven by base degradation to the keto a c i d 48. The high r e a c t i v i t y of these OH (18) 47 t H + 48 51 - 15 -compounds towards base might be the reason for the observed i n s t a b i l i t y of C which, when allowed to stand for three days at 0° had been about 30% converted, according to glpc, into one other product. B. Octahydro-4a,8a-epoxy-l(2H_)-naphthalenone (49) This epoxide was chosen in analogy to the tetrahydropentalenone epoxide 42. If 49_ would undergo the usual photochemical rearrangement reaction, the formation of kb_ and M) are possible. In this case the possible products h6_ and 5_0 are less strained than 43^  and j44_ and might therefore be formed in greater yields. (19) 49 46 50 Compound 49 was synthesized from the known 3,4,5,6,7,8-hexahydro-1 (2H_)-naphthalenone using alkaline hydrogen peroxide."^ Irradiation of epoxide 4j) i n dioxane through a Corex f i l t e r gave one product (50) only which could be collected by glpc in about 15% yield. One of the possible products, ^ 6_ i s a known compound."^ The i r spectrum of the isolated photoproduct has carbonyl bands at 5.73, 5.76 (shoulder), and 5.88 u. Compound 46 has carbonyl bands at 5.81 and 5.90 u. Assigning the 5.76 band of 50 to an impurity (a glpc analysis after the nmr had been run showed a new peak amounting to 10% - 16 -of the s t a r t i n g m a t e r i a l ) , the two remaining carbonyl bands could correspond to structure 50. The nmr of _50 shows a complex m u l t i p l e t from 7.3 to 8.6 T. Compound 4jj has been reported to have a t r i p l e t 16 at 7.38 T and a m u l t i p l e t from 7.65 to 8.60 t . This again rules out structure as the photoproduct. The mass spectrum of a sample that had not decomposed to any degree showed the correct parent peak. Hence, structure 50 i s very l i k e l y the one that has to be a t t r i b u t e d to the photoproduct of 49. C. 2-Cyclopentylidene-cyclopentanone oxide (52) This compound was chosen to add further proof to structure 50_ of the photoproduct of 49^ . If _52 would react photochemically undergoing the usual 1,2-shift of one of the g-substituents, compound _5_0 would be the only product formed. This product was expected to be i d e n t i c a l with (20) 52 50 49 the photoproduct obtained f rom 4-9_ thereby confirming the l a t t e r ' s s t r u c t u r e . The synthetic pathway leading to _5_2 was chosen i n analogy to the a l k a l i n e hydrogen peroxide epoxidation of 2-cyclohexylidene-cyclohexanone - 17 -(21) (22) . 5 5 52 Compound 55_ was synthesized by an a l d o l condensation of cyclopentanone 59 i n a l k a l i n e aqueous ethanol by the method of Huckel. When 55 was treated with a l k a l i n e hydrogen peroxide the product obtained showed a hydroxyl band in the i r spectrum and carbonyl bands at 5.79 and 5.90 u. It was thought that the epoxide might have opened under the re a c t i o n conditions used. Since i t i s known that temperatures above 20° cause the y i e l d of th i s type of re a c t i o n to drop considerably, the epoxidation 19 was c a r r i e d out at 12°. However, the same product containing an alc o h o l function was obtained. Using a large excess of hydrogen peroxide did not improve the y i e l d ; the a l c o h o l i c product was obtained i n about 10% y i e l d . When the pH of the reac t i o n mixture was checked a f t e r completion of the re a c t i o n (when the peak corresponding to 55_ had - 18 -disappeared i n the uv spectrum) i t turned out to be a c i d i c . At f i r s t t h i s was thought to be caused by r e a c t i o n of the a l k a l i n e s o l u t i o n with atmospheric carbon dioxide since the r e a c t i o n time for the epoxidation was long enough (about two days) to allow carbon dioxide to react with the base present i n s o l u t i o n . However, when the r e a c t i o n was c a r r i e d out under nitrogen atmosphere, the same product containing a hydroxyl function was obtained i n about 10% y i e l d . The same product was i s o l a t e d from another run where an excess of sodium hydroxide had been used. A new product was obtained i n 60% y i e l d from t h i s r e a c t i o n when the a c i d i f i e d (using' a c e t i c acid) r e a c t i o n mixture was extracted. The i r spectrum of t h i s product showed hydroxyl bands from 2.8 to 4.0 y which are c h a r a c t e r i s t i c f o r c a r b o x y l i c acids. I t also showed a strong carbonyl band at 5.86 u and a shoulder at 5.76 p. This compound might have been _56, obtained by the mechanism shown i n eq 23. 55 (23) 0 - 19 -It was somewhat s u r p r i s i n g that 5_5, the five-member ed r i n g analogue of 5_3 should not undergo epoxidation since the l a t t e r reacts so smoothly. However, i t was found i n the l i t e r a t u r e that systems of the type 57_ are anomalous i n t h e i r reactions with a l k a l i n e hydrogen . , 2 0 peroxide. 0 6< H Ph 57 58 House t r i e d to epoxidize ketone 5_8 with a l k a l i n e hydrogen peroxide 21 but a l l attempts f a i l e d . With a c l o s e r look at the mechanism of the epoxidation an explanation for the f a i l u r e of epoxidation of t h i s kind of system could be found. By a n u c l e o p h i l i c attack of the hydrogen peroxide anion on 59_, having two e x o c y c l i c double bonds, intermediate 60 i s formed which has one endocyclic double bond. This f i r s t step i s 59 60 61 22 e n e r g e t i c a l l y unfavorable according to a r u l e reported by H.C. Brown. This r u l e says that reactions w i l l proceed i n such a manner as to favor the formation or r e t e n t i o n of an exo double bond i n five-membered rings - 20 -and to avoid the formation or r e t e n t i o n of exo double bonds i n the six-membered r i n g systems. A few examples supporting t h i s r u l e are the two 1,3-diketones 62^ and 63 which are enolized to d i f f e r e n t degrees, and 6>4_ and (>5_ which upon heating isomerize to the products 66_ and 67_ predicted by the r u l e . C0 2Et 4.5% enol 76% enol 62 63 64 COCl 66 COCl (25) COCl COCl (26) 65 67 The enol form 68_ of j>2^  present only as 4.5% resembles the probably unfavorable intermediate 60_ formed by n u c l e o p h i l i c attack of hydrogen peroxide anion on 59_ with respect to the formation of an endocyclic double bond. - 21 -OH 68 In a related study of the addition of amines to ketone _5J5 very low yields of product 2P_ have been observed, compared to good yields 23 obtained in the case of the six-membered ring analogous compounds. 71 72 This was explained by the same argument used in the epoxy ketone case. The formation of intermediate 69_ was unfavorable on the basis of Brown's rule. In this case a reverse reaction i s possible which is favored in the five-membered ring case since the exocyclic resonance structure 71 contributes to a higher degree than does the unfavourable endo structure 72. Elimination i s favored from structure 71 and therefore favored - 22 -i n the five-membered r i n g case. Thus an unfavorable e q u i l i b r i u m or a slow attack of the amine account for the small y i e l d s observed. In the epoxide case, however, i t has to be the slow attack of peroxide anion which accounts f o r the f a i l u r e of r e a c t i o n since no reverse r e a c t i o n i s p o s s i b l e . In order to obtain the desired epoxide 5_2 another route was t r i e d as depicted i n eq 29. The preparation of 7_3 has been reported by 0 i •' OH (29) 52 74 Le G u i l l a n t o n who obtained best y i e l d s (65-70%) using potassium boro-24 hydride as the reducing agent. In t h i s work l i t h i u m aluminum hydride was used. Le G u i l l a n t o n obtained only a 45% y i e l d of 7_3 using t h i s reagent i n a molar r a t i o of 2.1 to 1 part of ketone 55. In the work-up he used acid which was found i n another case to cause isomerization of 25 the a l l y l i c a l c o hol formed (eq 30). Using water only i n the work-up increased the y i e l d of unrearranged alcohol dramatically (eq 31). OH OH 1) LiAlH, 2) H 30 + (30) 75 76 (31%) 77 (63%) 1) LiAlH. 75 76 (97%) 2) H 20 (31) In t h i s work l i t h i u m aluminum hydride and work-up without acid gave a 90% y i e l d of the c r y s t a l l i n e a l c o hol 7_3 whose melting point 24 agreed with that reported. Epoxidation of _7_3 with m-chloroperbenzoic acid gave epoxide 74. The nmr spectrum shows a t r i p l e t at 6.2 x f o r the proton on the carbon bearing the hydroxyl group. The hydroxyl proton appears at 7.2 x as a sharp s i n g l e t and the rest of the protons are found i n a m u l t i p l e t from 7.8 to 8.6 T. The stereochemistry of'74 has not been established. However, the hydroxyl group i s probably c i s t o the epoxy group since i t has been found that a l l y l i c alcohols are epoxidized s t e r e o s e l e c t i v e l y as f o r example 78 g i v i n g 79_.2^ - 24 -0 OH OH (32) (32) 78 79 The i s o l a t e d epoxy alcohol lk_ was found to be moderately unstable. A f t e r standing at 0° f o r fourteen days the i r showed a strong carbonyl band at 5.90 y and glpc showed that the compound had decomposed g i v i n g two major products. Because of t h i s low s t a b i l i t y , the mild C o l l i n s from oxidation was found by glpc and t i c to consist of a large number of products; a crude i n f r a r e d spectrum showed at l e a s t four d i s t i n c t carbonyl absorptions. As a r e s u l t , t h i s synthesis was abandoned. D. 0ctahydro-3a,8a-epoxy i-4(lH)-azulenone (80) This compound was chosen to prove the structure of the photoproduct of the naphthalenone epoxide 49. I f J30 would undergo the usual epoxy ketone rearrangement upon p h o t o l y s i s , s p i r o diketone J50_ would very l i k e l y be formed. This i s the structure t e n t a t i v e l y assigned to the photoproduct of 49. Compound 80_ might also rearrange to give .81, but probably to a lesser degree since J31 i s more st r a i n e d than 50. reagent was chosen f o r the oxidation of 74. 27 The mixture r e s u l t i n g - 25 -(33) 80 • 50 81 C34) 49 Epoxy ketone 80 was synthesized from 82 as shown i n eq 35. Hydrogena-t i o n of &2 gave . dike tone j3_3 i n qu a n t i t a t i v e y i e l d . According to a known procedure, r e f l u x i n g of J53 i n aqueous methanol containing 29 potassium carbonate gaye r i s e to azulenone 84 i n 66% y i e l d . Upon a l k a l i n e epoxidation of J54 with hydrogen peroxide, j30 was obtained i n qu a n t i t a t i v e y i e l d . (35) 80 84 - 26 -Epoxy ketone 8_0 was photolyzed i n dioxane using a Corex f i l t e r c u t t i n g o f f the l i g h t below 260 nm. The major part of j$0 polymerized. One product, 83_, was formed according to glpc. I t was c o l l e c t e d by glpc i n 3% y i e l d as a c o l o r l e s s l i q u i d having two carbonyl bands at 5.71 and 5.82 u. These bands did not correspond to 5i0 which had strong bands at 5.73 and 5.88 u. Structure j51 corresponding to the photo-product remains a p o s s i b i l i t y although the 5.71 u band seems to be of rather high frequency f o r a seven-membered 1 ,3-diketone. - 27 -SUMMARY Generally, the photolysis of internal a,3-epoxy ketones led mostly to products formed by polymerization. The low yield of monomeric photoproducts did not promise much synthetic use. Thus the entire project was abandoned. - 28 -PART I I THERMAL AND PHOTOCHEMICAL PROPERTIES OF cis,cis-CYCLODECA-3,8-DIENE-l,6-DIONE - 29 -INTRODUCTION A. Intramolecular Photochemical Cycloadditions of Non-conjugated Dienes Double bonds are able to undergo intramolecular photochemical c y c l o a d d i t i o n i n a s t r a i g h t or crossed manner. The general types of products so obtained are depicted i n eq 36 and 37. Since d i f f e r e n t - a c y c l i c systems (36) - c y c l i c systems (37) - 30 -r a t i o s of s t r a i g h t to crossed products were observed i n many systems, i t was of i n t e r e s t to study the f a c t o r s determining the changing r a t i o s . In 1967 Srinivasan reported an empirical r u l e p r e d i c t i n g the 30 d i r e c t i o n of c y c l o a d d i t i o n reactions. Table 1 summarizes a few of the examples on which the r u l e was based. I t can e a s i l y be seen that 1,4- and 1,6-dienes form p r e f e r e n t i a l l y s t r a i g h t products whereas 1,5-dienes add i n a crossed way. Since these reactions u s u a l l y occur v i a a t r i p l e t excited state they are very l i k e l y stepwise processes. The f i r s t step postulated by Srinivasan was the formation of a c y c l i c b i r a d i c a l intermediate. From the examples i n Table 1 i t can be seen that r a d i c a l s t a b i l i t i e s do not always account for the p r e f e r e n t i a l r e a c t i o n path. For compounds 87_ to 89_, r a d i c a l s t a b i l i t y would p r e d i c t the s t r a i g h t product to be the major one which i s contrary to what was observed. For example the most stable b i r a d i c a l intermediate formed from 8_8 would have structure 91_. This b i r a d i c a l would close to give 92 which i s the minor product observed. (38) 93 88 91 minor 94 92 Table 1. Mercury ( P^) S e n s i t i z e d Photolyses of Non-conjugated Dienes i n the Gas Phase. S t a r t i n g M a t e r i a l Straight Product Crossed Product Product r a t i o Crossed Straight C1,4 diene <• m 84 0.1 m 85 86 m 1,5 diene 87 88 O" none m <33 m 0.11 0.03 2.53 2.12 >40 89 1,6 diene' m <3 0.04 90 m = major product - 32 -Srinivasan postulated the Rule of Five which says that the c y c l o -a d d i t i o n prefers to go through a five-membered c y c l i c b i r a d i c a l intermediate. This r u l e predicts n i c e l y the p r e f e r e n t i a l formation of s t r a i g h t products f o r the 1,4- and 1,6-dienes and the crossed products for the 1,5-dienes. A much more s o p h i s t i c a t e d explanation f o r t h i s r u l e has not yet been found. Independent of Srinivasan's study L i u and Hammond reported some extensive work on the - t r i p l e t photosensitized i n t e r n a l a d d i t i o n 31 of a diene moiety to an i s o l a t e d double bond. Their r e s u l t s are compiled i n Table 2. I t i s i n t e r e s t i n g to note that 103a and 103b give the same r a t i o of products whether they are photolyzed separately or as a mixture. I t follows that they possess a common intermediate 110 having b i r a d i c a l character. Ring closure of 110 to the b i c y c l o [ 2 . 1 . 1 ] -hexane system i s thought to be slow compared to r o t a t i o n about a s i n g l e bond f o r two main reasons. F i r s t l y , the formation of a s t r a i n e d r i n g system should have a retar d i n g effect.. Secondly, the b i r a d i c a l intermediate should i n h e r i t t r i p l e t character from i t s precursor. P r i o r to closure of the b i r a d i c a l , spin i n v e r s i o n to the s i n g l e t state 32 has to occur which i s u s u a l l y slow. hv C39) 103b 110 103a - 33 -Table 2. Photosensitized Internal Addition of Dienes to O l e f i n s , 95 96 106 107 no a d d i t i o n product 98 m 108 109 no a d d i t i o n product q 101 hv 103a hv 102 104 + 105 5.8:1 hv 104 + 105 5.8:1 103b - 34 -According to L i u and Hammond the preference f o r formation of f i v e -membered rings may merely r e f l e c t the f a c t that the carbon atoms that become bonded are, on the average, c l o s e r together than those that would have to i n t e r a c t to form a six-membered r i n g . This s t a t i s t i c a l argument was c r i t i c i z e d because i t would require a highly oriented ground state of the substrate to account f o r the observed s p e c i f i c i t y of products, 33 a condition u n l i k e l y to be met with in the simple hydrocarbons used. White and Gupta suggested that the mode of the c y c l o a d d i t i o n i s determined by complex formation between the excited diene and the ground 33 state o l e f i n p r i o r to formation of the c y c l i c b i r a d i c a l intermediate. This theory, however, does not pr e d i c t the mode of cy c l o a d d i t i o n . I t i s i n t e r e s t i n g to note that i n r a d i c a l chemistry the Rule of Five i s e f f e c t i v e as w e l l . Decomposition of 6-heptenoylperoxide gives r i s e to r a d i c a l 111 which closes p r e f e r e n t i a l l y to the methylcyclopentane - 3 4 system. O - 6 * o »-111 30 : 1 The Rule of Five has been v e r i f i e d i n quite a few open chain systems. Only a few c y c l i c systems have been in v e s t i g a t e d , and one of these 35 was studied i n t h i s work. - 35 -B. E a r l i e r Results of the Photochemistry of 1,6-Cyclodecadiene Systems. Only a few i n v e s t i g a t i o n s have been reported on the photochemistry of 1,6-cyclodecadiene systems. In 1968 a mixture of cyclodecadienones 37 113 and 114 was photolyzed (eq 41). However, the geometry of bonds 2,3 and 3,4 was not known. Compound 116 i s formed following the Rule of Fiv e , however, 115 i s not. 0 115 (22%) 116 (32%) Another 1,6-cyclodecadiene was studied by Scheffer and Boire. Upon photolysis, diene 117 apparently obeys the Rule of Fi v e . The (42) 117 118 (50%) 119 (30%) t h i r d reported c y c l o a d d i t i o n of a 1,6-cyclodecadiene was that of germacrene D (120). Here again the r u l e of f i v e p r e d i c t s the major product, 121. + a-bourbonene + 6-copaene (crossed product) (43) 120 (-)-B-bourbonene (121) major C. Previous Results of the Photochemistry of cis,cis-Cyclodeca-3,8-diene-1,6-dione (82) 36 The c y c l i c c i s , c i s - d i k e t o n e 82 was studied by Scheffer and Lungle. It was used as a model to study photochemical intramolecular c y c l o -additions i n c y c l i c dienes where the double bond was i n the 3,y-position of a carbonyl function. Photolysis of 232_ gave the two products shown 36 i n eq 44. This was the f i r s t reported example of an intramolecular s s cy c l o a d d i t i o n of a 8,y-unsaturated ketone. A ir^ + ir^ concerted 40 cy c l o a d d i t i o n of 112 g i v i n g 122 i s photochemically not allowed. s s Photochemically allowed + TT^ c y c l o a d d i t i o n of J32_, e x i s t i n g i n the two conformations 123 and 124, would r e s u l t i n the formation of the t r i c y c l i c diketone 125 having a syn geometry which, however, was not 41 observed. Since 112 was found to be the only precursor of 122 and since t h i s conversion could not be concerted, a b i r a d i c a l intermediate - 3 8 -3 6 1 2 6 , formed upon e x c i t a t i o n of 8>2_ was postulated. The observed i n i t i a l 1 , 5-bonding i n 1 2 6 i s another example f o r the r u l e of f i v e . B i r a d i c a l 1 2 6 then closes s t e r e o s e l e c t i v e l y to give the anti-isomer 1 2 2 and not 1 2 5 , the syn-isomer. Closure of 1 2 6 without bond r o t a t i o n would r e s u l t i n a trans r i n g j u n c t i o n . Rotation about the 6 , 7-bond r e l i e v e s the non-bonded i n t e r a c t i o n between the hydrogens on C^ and C ^ Q > whereas an increased i n t e r a c t i o n between the hydrogens on C,. and would r e s u l t by r o t a t i o n about the 5 , 6-bond. The former r o t a t i o n being favored, closure leads to the formation of the anti-isomer 1 2 2 . 0 An a l t e r n a t i v e pathway i n v o l v i n g isomerization of 1 1 2 to the trans,trans-diketone and subsequent photochemically allowed [^2-s + 4 0 c y c l o a d d i t i o n could not be ruled out. When the i n v e s t i g a t i o n of the photolysis of J32 was near i t s completion a study on the p h o t o l y s i s of 4 2 the same compound was reported by Shani. However, the stereochemistry of the t r i c y c l i c ketone was claimed to by syn. This assignment was based on a hydrazone dimer 127, a l l e g e d l y formed from the t r i c y c l i c ketone' 125. The structure of 127 was based on the parent peak i n the 127 mass spectrum and on the C=N band i n the i r spectrum. This assignment was contradicted by a subsequent i n v e s t i g a t i o n by Stankorb and Conrow who demonstrated that the mass spectrum of the hydrazone d e r i v a t i v e had A 3 peaks at greater m/e values than the dimer parent peak. These peaks were a t t r i b u t e d to fragments of' hydrazone polymers. Since both the a n t i - and the syn-diketone 122 and 125 are p o t e n t i a l l y able to form polymers with hydrazine, t h i s cannot be used as a structure proof. I t should be noted that Stankorb and Conrow had strong arguments i n favor of the a n t i - c o n f i g u r a t i o n 122 on the basis of degradation experiments. D. Objectives of Present Research In order to shed more l i g h t on the mechanism of the photol y s i s of c i s , c i s - d i k e t o n e 82, the nature of the excited states involved was inve s t i g a t e d by quenching and s e n s i t i z a t i o n experiments. Another point of i n t e r e s t was the thermochemistry of c i s , t r a n s -cyclodeca-3,8-diene-l,6-dione (112). I t seemed conceivable that i t - 40 -would undergo a thermally allowed [ 2 + 2 ] cy c l o a d d i t i o n to form ° • J n s it a 40 syn or a n t i ketone 125 or 122. V i a th i s route the formation of the syn isomer 125 of t h i s dione was a p o s s i b i l i t y . I f 125 could be i s o l a t e d , i t , would c l a r i f y the assignment of the a n t i geometry to the t r i c y c l i c diketone obtained by photoly s i s of c i s , c i s - d i k e t o n e 82. A further point i n v e s t i g a t e d arose from the f a c t that gas chromatograms of even very pure samples of c i s , c i s - d i k e t o n e 82 always turned out to have a shoulder. This was suspected to a r i s e from a thermal product formed at the elevated temperature of the i n j e c t i o n port (about 200°) of the gas chromatograph. The po s s i b l e intermediacy of the trans-trans-isomer of 112 was inv e s t i g a t e d by low temperature p h o t o l y s i s . I t was thought that the ro t a t i o n b a r r i e r of the closure of the b i r a d i c a l 126 might be high enough to channel the rea c t i o n through the trans,trans-isomer. As a l a s t goal some further evidence f o r the a n t i - c o n f i g u r a t i o n of the t r i c y c l i c ketone 122 was gathered f i r s t l y by the r e s u l t s of a dipole determination, and secondly by comparing the i n f r a r e d and Raman spectra of 122. The l a t t e r method had been previously used to 44 d i f f e r e n t i a t e centrosymmetric from non-centrosymmetric molecules. - 41 -RESULTS AND DISCUSSION A. The Nature of the Excited State i n the Photolysis of cis_,cis_-Cyclodeca-3,8-diene-l,6-dione (a) Quenching Piperylene, a commonly used t r i p l e t quencher was chosen f o r t h i s i n v e s t i g a t i o n . According to glpc the same intermediate and f i n a l product were formed i n approximately the same r a t i o as i n the photolysis with no quencher present. Increasing the quencher concentration from 1.0 M to 10.0 M and at the same time the r a t i o of quencher to ketone from 20 to about 600 slowed the'reaction down by a f a c t o r of about 3. Thus, the quenching was not considered to be very e f f e c t i v e . Since t h i s i n d i c a t e d that the r e a c t i o n went v i a a s i n g l e t excited s t a t e , t r i p l e t s e n s i t i z a t i o n was expected to give a c l e a r answer. (b) S e n s i t i z a t i o n Benzophenone was the sensitizer of choice because i t absorbs at longer wavelengths than compound 82_. I t s t r i p l e t energy of 68.5 kcal/mole i s high enough to s e n s i t i z e ketones which normally have 45 t r i p l e t energies i n t h i s energy range. S e n s i t i z e d p h o t o l y s i s of 82^  i n benzene gave r i s e to the same two photoproducts as the d i r e c t p h o t o l y s i s . The two products had i d e n t i c a l r e t e n t i o n times i n glpc and on t i c . However, the rate of formation of the two photoproducts was d i f f e r e n t . On glpc the peak a t t r i b u t e d to the c i s , t r a n s intermediate - 42 -112 never amounted to more than about 5% of t o t a l reactants. This contrasted the d i r e c t photolysis where more intermediate (^50%) had 39 been formed before i t was eventually converted to the f i n a l product. This made i t d i f f i c u l t to i s o l a t e the intermediate i n the s e n s i t i z e d p h o t o l y s i s . By column chromatography the intermediate could only be obtained as a mixture with f i n a l product 122. The l a t t e r , however, could be i s o l a t e d as a pure compound and i t s i r and nmr spectra as w e l l as i t s melting point were i d e n t i c a l with the data of the product obtained by d i r e c t p h o t o l y s i s . The p o s i t i v e s e n s i t i z a t i o n r e s u l t s suggest that the r e a c t i o n goes v i a t r i p l e t excited states. The negative quenching r e s u l t s lead to the conclusion that the chemical r e a c t i o n i s so f a s t that quenching rates cannot compete with i t , or much less probable, that the s i n g l e t excited state gives r i s e to the same products as does the t r i p l e t s t a te. A t h i r d very u n l i k e l y way to explain the negative quenching would be to assume that compound 27_ had a lower t r i p l e t energy than piperylene (E^ a, 61 kcal) i n which case the piperylene would not be able to accept energy from a lower energy d o n o r . ^ B. Thermolysis of cis,trans-Cyclodeca-3,8-diene-l,6-dione (112) As was pointed out before, i t was conceivable that the c i s , t r a n s -intermediate 112 might thermally c y c l i z e i n an allowed concerted [ 2 + 2 ] addition to the same product (122) obtained by p h o t o l y s i s . Tr s TT a v — - J r J Thermolysis of 112 i n xylene for f i v e days at 192° gave r i s e to three products 128, 129 and 130 i s o l a t e d by glpc i n y i e l d s of 9%, 5% and 1% r e s p e c t i v e l y . From mass s p e c t r a l data 128 and 129 were found to be - 43 -isomers of 112. The i r spectrum of 128 which was obtained as c o l o r l e s s c r y s t a l s showed carbonyl bands at 5.72 and 5.95 u. The former band points to a five-membered r i n g ketone and the 5.95 u band might be a t t r i b u t e d to an a,g-unsaturated ketone. The uv spectrum supports the l a t t e r assignment since i t has a high e x t i n c t i o n c o e f f i c i e n t of 14,000 at 226 nm. In the nmr spectrum the o l e f i n i c proton on the carbon g to the carbonyl group appears as a doublet of doublets at 2.98 T with coupling constants of. 10 and 2 Hz. The o l e f i n i c a-proton shows up as a doublet of doublets at 4.00 T and coupling constants of 10 and 3 Hz. The coupling constant of 10 Hz can be assigned to a c i s double bond. The nmr further shows a complex m u l t i p l e t of 9 protons from 7.0-8.3 T and a doublet of three protons at 8.83 T with a coupling constant of 6 Hz. The mass spectrum shows a parent peak at m/e 164 from which i t follows that 128 i s isomeric with s t a r t i n g m a t e r i a l . However, a peak appeared at m/e 211 amounting to about 10% of the parent peak. A molecule incorporating a five-membered r i n g ketone and an a,3-unsaturated 47 ketone might a r i s e from an ene-reaction of 112. The p r i n c i p l e of t h i s thermal r e a c t i o n i s shown i n eq 47. I f 112 undergoes an ene-reaction (47) - 44 -one of the possible products would a r i s e v i a the mechanism shown i n eq 48. The s p e c t r a l data would f i t structure 131 except f o r the doublet at 8.83 T i n t e g r a t i n g to three protons. I t i s not c l e a r how three 0 (48) protons of 128 would give r i s e to the simple doublet at f a i r l y high f i e l d . Compound 129, a c o l o r l e s s l i q u i d , had v i r t u a l l y i d e n t i c a l carbonyl bands i n the i r as d i d 128. However, the nmr was more complex. One v i n y l proton appeared as a complex m u l t i p l e t from 2.8 to 3.5 T. At 4.0 T i t had a doublet of t r i p l e t s with coupling constants of 10 Hz for the doublet s p l i t t i n g and 3 Hz f o r the t r i p l e t s p l i t t i n g . As i n 128• a m u l t i p l e t extended from 7.0 to 8.3 T. In the high f i e l d part of the spectrum two doublets could be seen at 8.75 and 8.82 x.' The l a t t e r s i g n a l corresponds to the doublet at 8.83 x found for 128. Although 129 did not contain more than 5% of 128 according to glpc, the spectrum of 129 looked l i k e a mixture of approximately two parts of 128 to one part of a new compound. The l a t t e r might have been an isomer of 131 with another geometry at the r i n g j u n c t i o n . The mass spectrum of 129 showed a parent peak at m/e 164. However, an a d d i t i o n a l peak amounting to about 15% of the parent peak was located at m/e 181, corresponding to the ad d i t i o n of water to an isomer of 112. Compound 130 which was - 45 -obtained i n 1% y i e l d only gave an nmr spectrum which was s i m i l a r to the spectra of 128 and 129. However, none of the spectra of these three 2 6 thermal products resembled a tricyclo[3.3.0.0 ' ]cyclodeca-4,9-dione str u c t u r e . A thermally allowed c y c l o a d d i t i o n of 112 to give 122 or 125 could not be detected and the a l t e r n a t i v e thermal pathways were not pertinent and promising enough to be further pursued. C. Thermolysis of cis,cis-Cyclodeca-3,8-diene-l,6-dione (82) Since even very pure samples of 82^  gave r i s e to a shoulder or even a second peak on gas chromatograms, a thermal r e a c t i o n of J52 was thought to occur i n the i n j e c t i o n port of the gas chromatograph. When 82 was thermolyzed i n toluene at 145° for two days most of the s t a r t i n g m a t e r i a l reacted to give besides probably polymeric compounds one product which was thought to have structure 132, i n a y i e l d of 23%. 82 133 132 The r e a c t i o n leading to 132 i s e f f e c t i v e l y an intramolecular A l d o l condensation. Structure 132 i s supported by the nmr spectrum which shows a complex m u l t i p l e t f or the four v i n y l protons at 4.2 T. The bridgehead proton 3a appears quite downfield at 6.2 T as a broad s i n g l e t . - 46 -The large downfield chemical s h i f t of t h i s proton might be caused by the combined factors of i t s being a l l y l i c , t e r t i a r y , and a to a carbonyl p o s i t i o n . The two protons at appear as a doublet (J = 4 Hz) at 6.8 T which corresponds to the chemical s h i f t of the a proton of a 36 3,y-unsaturated ketone (as i n 82). The r e s t of the protons appear as a m u l t i p l e t from 7.4 to 7.7 T. A sharp peak w i t h i n t h i s m u l t i p l e t can be s h i f t e d u p f i e l d upon d i l u t i o n and i s therefore a t t r i b u t e d to the hydroxyl proton. The i r spectrum shows a hydroxyl band at 2.88 u and the carbonyl band at 5.88 u, the l a t t e r being the same frequency 36 as that measured for 82. The presence of g,y-unsaturated ketone i s furt h e r supported by the uv spectrum having a maximum at 290 nm with an e of 98. This enhanced e x t i n c t i o n c o e f f i c i e n t i s quite c h a r a c t e r i s t i c 48 of g ^ - unsaturated ketones. Saturated ketones have e values of about 20. The geometry of the r i n g j u n c t i o n could not be determined on the basis of the data obtained. The mass spectrum shows the correct parent peak at m/e 164. Further evidence for the structure of 132 was obtained by chemical degradation. Hydrogenation of 132 gave ketoalcohol 134 (eq 50). The (50) OH OH 132 134 - 47 -nmr spectrum shows the 3a proton as a doublet of tri p l e t s (J^ = 2Hz, J = 7 Hz) at 6.8 T. The protons a to the carbonyl function appear at 7.5 T. The rest of the protons are included in a multiplet from 7.8 to 8.6 T. The hydroxyl proton can be shifted upfield by dilution. The i r spectrum shows a strong hydroxyl band at 2.91 u and a carbonyl band at 5.90 u corresponding to a seven-membered ring ketone. As a 3-hydroxy ketone 134 should be dehydrated easily by base or acid catalysis. Since J33 was known to give jB4_ upon refluxing i n aqueous methanol containing potassium carbonate, the same conditions 28 were used to dehydrate 134. The isolated product was 84 which was (51) independently synthesized via 83 according to known procedures in 28 the f i r s t part of this thesis. The i r spectra of the products obtained by these two different ways were superimposable showing a carbonyl band at 6.03 u. Unfortunately the stereochemistry of the ring junction i s lost i n the dehydration step. However, the readiness of the dehydration to occur with a relatively weak base like potassium carbonate might indicate a trans ring junction which allows easy trans elimination of water. However, both isomers of 134 have been reported to dehydrate readily in cyclohexane solution in sealed 49 tubes at 212°. - 48 -D. Low Temperature Photolysis of cis,trans-Cyclodeca-3,8-diene-1,6-dione As was pointed out previously, trans,trans-cyclodeca-3,8-diene-1,6-dione (135) i s s t e r i c a l l y arranged to undergo c y c l o a d d i t i o n to give .122 (eq 52). H (52) 1) 6,7 bond r o t a t i o n 135 122 In order to be able to trap 135, pathway (a) has to be favored over pathway (b). Also, r e a c t i o n (e) should not be much f a s t e r than (b). Step (d) requires a f a i r amount of thermal a c t i v a t i o n energy f o r r i n g closure of the v i b r a t i o n a l l y deactivated b i r a d i c a l 126. However, the back reaction (c) has probably a lower a c t i v a t i o n energy since E f o r the tetramethylene b i r a d i c a l 136 i s smaller than E . - 49 -E a (53) 136 It was therefore thought that at low temperatures b i r a d i c a l 126 which i s analogous to 136 might not close to give 122 but rather revert to give s t a r t i n g m a t e r i a l 112. The l a t t e r would then react v i a path (b) to give the trans,trans-diketone 135. Subsequently, 135 would cycloadd to give 122 i n step (e) which would probably be concerted and not temperature dependent. Photolysis of 112 at 77°K i n EPA (ether, iso-pentane, and ethanol) which forms a c l e a r g l a s s , gave r i s e to the t r i c y c l i c ketone 122 as the major product. To a l e s s e r degree 112 isomerized back to the c i s , c i s - d i k e t o n e 82. The rate of r e a c t i o n at 77°K was slowed down compared to the run under the same conditions at room temperature by a f a c t o r of about eight. The products formed were compared by co-i n j e c t i o n of authentic compounds i n t o the gas chromatograph and by comparison of R^ values on t i c . I t might be that the trans,trans isomer 135 would not be very st a b l e because of ir-electron repulsions. These were found to determine the s t a b i l i t y of the isomers of 1,6-cyclodecadienes.^"'" Isomerization experiments on these compounds by means of photochemically produced benzenethiyl r a d i c a l s to give thermodynamic product d i s t r i b u t i o n s - 50 -showed 96% ci s , c i s - i s o m e r , 3.8% c i s , trans isomer and no trans, trans isomer. The c i s , c i s isomer can avoid ^ - e l e c t r o n repulsion by a chair l i k e conformation whereas the trans,trans isomer cannot. The chair conformation 124 was also found to be more stable than the boat conforma-41 t i o n 123 i n the case of cis,cis-cyclodeca-3,8-diene-l,6-dione. ' ^ - (54) 124 123 2 6 E. Configuration of Tricyclo[5,3.0.0 ' ]deca-4,9-dione Ca) Dipole Moment A syn structure 125 was assigned by Shani to the f i n a l product 42 of the photolysis of cis,cis-cyclodeca-3,8-diene-l,6-dione (82). However, Scheffer and Lungle and Stankorb and Conrow assigned the a n t i 36 A3 structure 122 (cf. Introduction). ' To,add furt h e r proof to the 52 conf i g u r a t i o n , a dipole measurement was c a r r i e d out. The a n t i c o n f i guration having a centre of symmetry was expected to give r i s e to a very small dipole moment, whereas the syn diketone 125 would probably have a large dipole moment. The moment measured turned out to be 1.45 D. This r e l a t i v e l y high dipole moment (.y cyclopentanone = 2.89 - 3.03) may be caused by 53 conformational d i s t o r t i o n s i n the molecule. This i s not very unusual since centrosymmetric molecules l i k e 137, 138 and 139 have dipole moments i n the same range as 122.^4,55,56 ^he large dipole moment 1,4-cyclohexadione has been assigned to the importance of boat structure 140. 137 u = 1.26 D 138 u = 1.19 D 0 139 140 u = 1.09 D 52 -The dipole moment of 122, 1.45 D, while somewhat higher than expected, does not rule out the centrosymmetric anti geometry of 122. (b) Vibrational Spectroscopy Vibrational spectroscopy provides a tool to distinguish centro-symmetric from non-centrosymmetric molecules. The Rule of Mutual Exclusion states that for centrosymmetric molecules a vibrationally active infrared transition cannot be active i n the Raman and vice versa for active Raman transitions."^ Therefore no coincidences should be observed between the two spectra for centrosymmetric molecules. However, in large molecules the possi b i l i t y for accidental coincidences increases because of the great number of vibrations and the occurrence of combinations and overtones. Nevertheless, i t has been found that the difference in the number of coincidences in the spectra of centro-symmetric vs_. non-centrosymmetric molecules i s significant enough for 44 not too complex molecules to allow the determination of their symmetry. In the case of photodimers 124 and 141 of cyclopentenone six coincidences 44 were found for 124 and twenty-six for 141. 0 0 0 124 141 Proceeding to larger molecules l i k e 142 and 143 one finds ten coincidences 44 for 142 and sixteen for 143. This difference i s not sufficiently great to allow an unambigous symmetry assignment. 142 143 The t r i c y c l i c diketone 122 should be small enough to allow a cl e a r determination of i t s symmetry. Two bands were considered to be coi n c i d i n g i f they were l y i n g w i t h i n a range of f i v e wavenumbers, since the accuracies of the i r and Raman spectrophotometer were 2-3 cm * each. Out of twenty d i s t i n c t bands i n the Raman and twenty-six bands i n the i r spectrum, seven coincidences were found. This compares w e l l with the s i x coincidences found f o r the centrosymmetric cyclopentenone dimer 124. As a r e s u l t of t h i s , the a n t i c onfiguration 122 i s once more supported. - 54 -EXPERIMENTAL General Infrared ( i r ) spectra were recorded on Perkin-Elmer Model 137 and Model 700 spectrophotometers using sodium ch l o r i d e c e l l s . Nuclear magnetic resonance (nmr) spectra were recorded by Miss P. Watson and Mr. R. Burton of t h i s department on the following spectrometers: Varian Model A-60, T-60, and HA-100, and Jeolco Model C-60H. TMS was used as an i n t e r n a l standard. U l t r a v i o l e t (uv) spectra were recorded on a Unicam Model SP 800 B spectrophotometer using methanol as solvent unless otherwise i n d i c a t e d . An AEI-MS-9 spectrometer was used f o r mass spectra, recorded by Mr. G.D. Gunn of t h i s department. Micro-analyses were performed by Mr. P. Borda of t h i s department. Melting points were determined on a Fisher-Johns melting point block and are a l l uncorrected. For gas l i q u i d p a r t i t i o n chromatography (glpc) Varian Aerograph Model 90 P and Varian Aerograph Autoprep Model A 700 were used. Both were connected to Honeywell E l e c t r o n i k 15 s t r i p chart recorders. The flow rate of helium as the c a r r i e r gas was approximately 60 ml/min. The following a n a l y t i c a l columns (5' x 1/4") were used: 20% SE-30 on 60/80 Chromosorb W A/W DMCS, (column A); 3% SE-30 100/120 Varaport 30, (column B); 5% QF-1 60/80 Chromosorb W, (column C); 20% DEGS 60/80 Chromosorb W, (column D). The column temperatures are given i n parentheses a f t e r the column s p e c i f i c a t i o n s . For column Chromatography s i l i c a g e l (<0.08 mm) from E. Merck AG, Darmstadt was used under 5-10 p s i nitrogen pressure. Thin layer chromatography ( t i c ) plates were developed i n iodine chambers and prepared with S i l i c a Gel G for t i c acc. to Stahl (10-40 u). Photolyses were performed by means of a 450 watt medium pressure Hanovia lamp placed i n a water-cooled quartz immersion w e l l . A l l s o l u t i o n s were degassed at l e a s t 15 min. p r i o r to photolysis with L grade nitrogen or argon. Unless otherwise mentioned, a l l organic compounds used were reagent grade. Epoxidation of 3,4,5,6-Tetrahydro-l(2H)-pentalenone (41) The s t a r t i n g m a t e r i a l was a g i f t from the "Badische A n i l i n und . Soda Fabrik" (BASF) to which the author would l i k e to express h i s gratitude. Pentalenone 41- was r e c r y s t a l l i z e d from low b o i l i n g petroleum ether at approximately -30° under nitrogen. The i n i t i a l i mpurities could be reduced to 1-2% (checked by glpc, column A, 149°). The i r spectrum of a p u r i f i e d sample was i d e n t i c a l with the one reported by r 58 Cope. 19 For the epoxidation, the procedure of Wasson and House was used. A s o l u t i o n of 1.493 g (12.2 mmol) of p u r i f i e d 41 and 3.8 ml (37 mmol) of 30% hydrogen peroxide i n 12 ml methanol was cooled to 15° by means of an i c e bath. To t h i s s o l u t i o n 1 ml of 6 N sodium hydroxide was added dropwise with s t i r r i n g over a period of three hours. During the a d d i t i o n the temperature of the r e a c t i o n mixture was maintained at 15-20° with a bath of coid water. A f t e r the a d d i t i o n was complete, the temperature was kept at 20-25°. The re a c t i o n was monitored by uv. A f t e r 3.5 hr the band of the unsaturated ketone at 240 nm had disappeared. A l l the glassware used f o r the work-up was washed with a l k a l i n e water - 56 -p r i o r to use. The water used f o r washing the organic layers was also rendered a l k a l i n e by adding a drop of 6 N sodium hydroxide to i t . A f t e r the reaction was complete the r e s u l t i n g mixture was poured i n t o 15 ml of cold water and extracted with 2 x 15 ml of cold ether. The organic layers were washed with 20 ml of water and drie d over magnesium s u l f a t e at 0° and subsequently concentrated i n vacuo. This e x t r a c t i o n procedure was repeated with 2 x 15 ml of chloroform. The combined concentrated layers gave 1.135 g (8.24 mmol, 68%) of hexahydro-3a,6a-epoxy-l(2H)-pentalenone (42), a c o l o r l e s s l i q u i d which c r y s t a l l i z e d at approximately 0°; i r (CHC1 3) 5.78 (C=0) y; nmr (CDCl 3) T 7.2-8.1 (m); uv max (ethanol) 300 nm; mass spectrum (70 eV) m/e parent 138. Photolysis of Hexahydro-3a,6a-epoxy-l(2H)-pentalenone (42) A s o l u t i o n of 1.007 g of 47 i n 400 ml of benzene was degassed and photolyzed using a Pyrex f i l t e r . The r e a c t i o n was followed by glpc (column A, 130°). A f t e r 30.5 hr most of the s t a r t i n g m a t erial had disappeared and four major products were formed (A, B, C, and D i n the order of increasing r e t e n t i o n time; the respective r a t i o s were 2:2:10:3). Half of the rea c t i o n mixture was concentrated under vacuum and the product c o l l e c t e d by glpc (column A, 130°). Compound A was obtained i n the form of c o l o r l e s s n e e d l e l i k e c r y s t a l s (6 mg, 1% by weight): i r (CHC1 3) 5.57 (s, C=0), 5.80 (sh, C=0), 5.85 (s, C=0) u. Compound B (5 mg, 1% by weight), a c o l o r l e s s l i q u i d , consisted of three d i f f e r e n t products when checked by r e i n j e c t i o n i n t o the gas chromatograph. Compound C was a c o l o r l e s s l i q u i d (24 mg, 5% by weight); i r (CHC1J 5.57 (s, C=0) , 5.75 (s, C=0) y; nmr (CDC1J T 7.36 (center . - 57 -of m, 6), 7.7-8.3 (broad m, 4). Compound D was a c o l o r l e s s l i q u i d (8 mg, 1.5% by weight); i r (CHC13) 5.80-5.93 (m, C=0), 6.15 (s) p. Compound C p a r t l y decomposed cn standing for three days at 0° to a compound having the same retention time (glpc) as A. Photolysis of 0ctahydro-4a,8a-epoxy-l(2H)-naphthalenone (49) The author expresses h i s gratitude to J . Balf of t h i s department f o r a sample of 49. A s o l u t i o n of 44 mg (0.26 mmol) of epoxy ketone 4^9 i n 7 ml of dioxane (dried over molecule sieve 5A) was degassed and photolyzed using a Corex f i l t e r . The re a c t i o n was monitored by glpc (column B, 115°), and a f t e r 8.5 hr one product was formed and a l l s t a r t i n g m a terial had disappeared. A f t e r concentration i n vacuo and c o l l e c t i o n by glpc (column B, 115°), 7 mg of a c o l o r l e s s l i q u i d (50) was obtained. No decomposition had occurred since r e i n j e c t i o n of _5jO gave the same s i n g l e peak as obtained i n the c o l l e c t i o n ; i r (film) 5.73 (s, C=0) , 5.76 (sh), 5.88 (s, C=0) y; nmr (CDC1 3) T 7.3-8.6 (m); mass spectrum (70 eV) m/e parent 166. The compound was checked a f t e r the nmr spectrum had been recorded and i t was found that about 10% had decomposed to give a second peak on glpc (column B, 115°). Epoxidation of 2,3,5,6,7,8-Hexahydro-4(lH)-azulenone (84) For the synthesis of 8_4_ from 1,6-cyclodecadione see Experimental of the second part of t h i s t h e s i s . The same procedure was followed as i n the epoxydation of _41_ using 252 mg (1.68 mmol ) of 84) i n 6 ml of methanol, 90 mg (2.25 mmol) of - 58 -sodium hydroxide i n 0.5 ml of water, 2 ml of methanol, and 2 ml of 30% hydrogen peroxide (19.5 mmol). The rea c t i o n was followed by uv and was complete a f t e r 6 hr. A f t e r work-up, 273 mg (1.64 mmol, 98%) of octahydro-3a,8a-epoxy-4(lH)-azulenone (80) was obtained as a c o l o r l e s s l i q u i d ; i r (film) 5.91 (s, C=0) u; uv max (cyclohexane 303 nm (e 20, n - r r * ) . The gas chromatogram (column B, 101°) showed one peak only. Photolysis of 0ctahydro-3a,8a-epoxy-4(lH)-azulenone (80) A s o l u t i o n of 50 mg (0.30 mmol) of epoxy ketone 80_ i n 7 ml of dioxane (dried over molecular sieve 5A) was degassed and photolyzed using a Corex f i l t e r . The re a c t i o n was followed by glpc (column B, 101°) and was stopped a f t e r 78 hr. At t h i s point glpc showed that s t a r t i n g material had been completely consumed and a small amount of a new product had been formed. I t s peak on glpc was very broad. However, i t could be sharpened by d i s s o l v i n g the concentrated photolysis mixture i n low b o i l i n g petroleum ether. The soluble part was concentrated i n vacuo and the product c o l l e c t e d by glpc (column B, 101°) to give 1.5 mg of a c o l o r l e s s l i q u i d ; i r (film) 5.71 (s, C=0), 5.82 (s, C=0) u. A r e i n j e c t e d and c o l l e c t e d sample showed two minor peaks at very long re t e n t i o n times. 2-Cyclopentylidene-cyclopentanone (55) 59 The procedure of Huckel was followed. To 50 g (0.595 mole) of cyclopentanone dissolved i n 100 ml of ethanol a s o l u t i o n of 3.6 g potassium hydroxide i n 45 ml of water was added. The r e s u l t i n g mixture turned dark red during the four days i t was allowed to stand at 0°. - 59 -Af t e r concentration under vacuum, the s o l u t i o n was extracted with ether and the organic layers dried over magnesium s u l f a t e . Concentra-t i o n i n vacuo gave 43.0 g of a dark red liquid,24 g of which were d i s t i l l e d under vacuum to give 14.4 g (0.096 mole, 58%) of 2-cyclo-pentylidene-cyclopentanone (bp 88-90°/0.3 mm); i r (film) 5.85 (s, C=0), 6.10 (s C=C) y; nmr (CCl^) T 7.3-8.4 (m); mass spectrum (70 eV) m/e 60 parent 150; oxime mp 125° ( l i t . 126.5°). Thin layer chromatography (20% ether/chloroform) showed one spot. Glpc (column D, 150°) showed one peak only. The compound had to be i n j e c t e d with solvent. Otherwise i t seemed to decompose since i t gave r i s e to numerous broad peaks. 2-Cyclopentylidene-cyclopentanol(73) A procedure which was s u c c e s s f u l i n the reduction of m e s i t y l 25 oxide was used. A s o l u t i o n of 511 mg (3.4 mmol) of 2-cyclopentylidene-cyclopentanone i n 5 ml of dry ether was added to 67 mg (1.97 mmol) of l i t h i u m aluminum hydride i n 5.ml of dry ether so as to maintain gentle r e f l u x . A f t e r 5 min, excess l i t h i u m aluminum hydride was cautiously destroyed with i c e water, and more water (20 ml) added. The aqueous s l u r r y was washed with 3 x 7 ml of ether and the ether layers washed, dried over magnesium s u l f a t e , and concentrated i n vacuo to give 462 mg (3.04 mmol, 90%) of c o l o r l e s s c r y s t a l l i n e 73, mp 53-55° 24 C l i t . 50°); i r (CC1 4) 2.78-3.02 (OH) y; nmr (CC± 4) T 5.61 (broad s, 1, HCC0H)CH=C<), 7.40 (s, 1, OH), 7.50-8.10 (m, 6, a l l y l i e methylene), and 8.10-8.50 (m, 8, methylene). Thin layer chromatography (50% chloroform/ether) showed one spot which turned green by developing i n iodine. - 60 -2-Cyclopentylidene-cyclopentanol oxide (74) A s o l u t i o n of 372 mg (2.45 mmol) of 2-cyclopentylidene-cyclopentanol i n 3 ml of chloroform was cooled to 0° and 555 mg (3.21 mmol) of m-chloroperbenzoic acid i n 10 ml of chloroform added i n 1 ml a l i q u o t s every ten minutes with s t i r r i n g . Ten minutes a f t e r the l a s t a d d i t i o n the r e a c t i o n mixture was washed with 10 ml of a saturated sodium bicarbonate s o l u t i o n and subsequently with 10 ml of water. A f t e r drying over magnesium s u l f a t e and concentration i n vacuo 407 mg (2.42 mmol, 99%) of 2-cyclopentylidene-cyclopentanol oxide, a s l i g h t l y yellow l i q u i d , was obtained. Thin layer chromatography (50% benzene/ethyl acetate) showed one major spot and a f a i n t minor spot having a smaller value; i r (film) 2.94 (OH, s ) ; 5.90 (w, C=0) u; nmr (CC1 4) x 6.2 ( t , 1, J = 5 Hz, HC(0H)<), 7.2 (s, 1, OH), 7.8-8.6 (m, 14). This compound p a r t i a l l y decomposed a f t e r standing at 0° f o r 14 days. (The i r band at 5.90 u had very much increased i n i n t e n s i t y . ) Glpc (column B, 101°) of the decomposed compound showed two major and 4 minor peaks. . Dipyridine-chromium(VI) oxide Complex*^ A t o t a l of 5 g of chromium(VI) oxide (dried over phosphorus pentoxide) was added i n small portions to 40 ml of anhydrous py r i d i n e with s t i r r i n g at 15-20°. Caution: adding p y r i d i n e to chromium(VI) oxide r e s u l t s i n inflammation. The s t i r r i n g was continued u n t i l the i n i t i a l l y yellow p r e c i p i t a t e turned red ( a f t e r a few hours). The complex was i s o l a t e d by washing several times with low b o i l i n g petroleum ether, f i l t r a t i o n , and drying at about 10 mm pressure (higher vacuum causes surface decomposition). - 61 -Oxidation of 2-Cyclopentylidene-cyclopentanol Oxide (74) 27 The oxidation procedure of C o l l i n s was applied. A s o l u t i o n of 100 mg (0.595 mmol) of 7_4 i n 5 ml of methylene c h l o r i d e was added to a s l u r r y of 960 mg (3.72 mmol) of the complex i n 20 ml of methylene c h l o r i d e . The r e s u l t i n g mixture was s t i r r e d f o r one hour, excluding any moisture by means of an attached drying tube. A f t e r washing with water and sodium bicarbonate the mixture was treated with N o r i t , f i l t e r e d , d r i e d , and concentrated i n vacuo to give 60 mg of products. Thin l a y e r chromatography (50% benzene/ethyl acetate) showed 2 spots, one of them being an impurity already present i n the s t a r t i n g m a t e r i a l . Glpc (column B, 101° and C,95°) showed one major (^40%) and seve r a l minor peaks; i r (CHCl-j) 5.72 (m, C=0) , 5.79 (m, C=0) , 5.86 (sh, C=0) , 5.90 (m, C=0) u; s t r u c t u r e l e s s f i n g e r p r i n t region bands. Due to lack of s t a r t i n g material and to the d i f f i c u l t y encountered i n t h i s oxidation, t h i s synthetic sequence was abandoned. Photolysis of cis,cis-Cyclodeca-3,8-diene-l,6-dione i n the Presence of Piperylene as a Quencher Three runs were done with d i f f e r e n t piperylene concentrations. The diketone 82 (synthesis see r e f . 28) was dissolv e d i n benzene, except i n run 3', and piperylene (tech. grade, d i s t i l l e d under nitrogen) was added, the r e s u l t i n g mixture degassed f o r 15 min and photolyzed using a Pyrex f i l t e r and the external p h o t o l y s i s f l a s k . The l a t t e r consisted of a test-tube l i k e f l a s k made of quartz g l a s s . For the photolysis t h i s f l a s k was clamped close to the regular immersion w e l l and both were surrounded by a water f i l l e d beaker which provided the - 62 -cooling of the external f l a s k . The r e a c t i o n was followed by glpc (column A, 150°). Authentic cis,trans-cyclodeca-3,8-diene-l,6-dione 2 6 and c i s , a n t i , c i s - t r i c y c l o [ 5 . 3 . 0 . 0 ' ]decane-4,9-dione had i d e n t i c a l r e t e ntion times as the products formed i n the presence of piperylene. They were formed i n approximately the same r a t i o as i n the d i r e c t p h o t o l y s i s . Run 1 Run 2 Run 3 weight of 82 50 mg 33 mg 8 mg benzene 6 ml 16 ml -piperylene 400 mg (6 mmol) 2.70 g (40 mmol) 2.03 g (30 mmol) molarity of 82 0.047 0.01 0.016 molarity of quencher 0.94 2.0 10.0 r e a c t i o n time <vL.5 hr ^1 hr a-1.5 hr Cuntil no 82 l e f t ) P h o tolysis of cis,cis-Cyclodeca-3,8-diene-l,6-dione (82) i n the Presence of Benzophenone as a S e n s i t i z e r A s o l u t i o n of the diketone 82_ 225 mg (1.37 mmol) and 1.00 g (5.5 mmol) of benzophenone were dissol v e d i n 15 ml of benzene i n the external photo l y s i s f l a s k . Between the l a t t e r and the immersion w e l l a Corning f i l t e r was introduced (C.S. Number 0-52, glass number 7380) absorbing a l l the l i g h t at X < 340 nm. The diketone has no absorption at X > 340 nm i n benzene. The uv spectrum of benzophenone was measured i n benzene uv max 344 nm (e 240). The p h o t o l y s i s of the degassed s o l u t i o n was followed by glpc (column A, 150°) and t i c . The two products formed were i d e n t i c a l according to glpc and t i c (70% ether/n-hexane) to the - 63 -ones formed by photolysis i n bezene using a Pyrex f i l t e r and no s e n s i t i z e r . A f t e r 22 hr of p h o t o l y s i s , when no s t a r t i n g m a t e r i a l was l e f t , the solvent was evaporated. Most of the benzophenone could be removed by extracting the crude r e a c t i o n mixture with n-hexane. The in s o l u b l e part (268 mg) was separated on a chromatography column (60% 2 6 ether/n-hexane). From t h i s 50 mg of c i s , a n t i , c i s - t r i c y c l o [ 5 . 3 . 0 . 0 ' ]-decane-4,9-dione could be i s o l a t e d . The i r and nmr spectra as w e l l as the melting point of t h i s m a t e r i a l were i d e n t i c a l with those of authentic m a t e r i a l . The c i s , t r a n s intermediate 112 never exceeded 5% of t o t a l reactants during the p h o t o l y s i s . This made i t d i f f i c u l t to i s o l a t e i t . ' What was i s o l a t e d a f t e r column chromatography was a mixture of the intermediate and the f i n a l product 122 according to t i c (60% ether/hexane). The i r spectrum of t h i s mixture showed a carbonyl band at 5.88 y corresponding to the carbonyl band of c i s , t r a n s diketone 112. A shoulder at 5.78 y corresponded to the t r i c y c l i c diketone 122 present according to t i c . The f i n g e r p r i n t region was not superimposable with the spectrum of authentic c i s , t r a n s diketone 112. However, i t showed the 14.1 y band, a strong band i n the spectrum of c i s , t r a n s diketone 112. In order to make sure that no r e a c t i o n occurred without s e n s i t i z e r , 35 mg of S!2 were photolyzed i n 10 ml of benzene under the same conditions as with the s e n s i t i z e r present. Even a f t e r 6 hr photoly s i s no r e a c t i o n had taken place according to glpc (column A, 151°). Thermolysis of cis,cis-Cyclodeca-3,8-diene-l,6-dione (82) A s o l u t i o n of 234 mg of J32 i n 10 ml of toluene was kept at 145° for two days in a sealed Pyrex tube i n a sublimation apparatus. The - 64 -r e s u l t i n g brown s o l u t i o n was treated with Norit and extracted with low b o i l i n g petroleum ether i n order to separate polymeric materials formed i n the rea c t i o n . Thin layer chromatography (50% e t h y l acetate/ chloroform) showed one-product and a f a i n t spot corresponding to s t a r t i n g m a t e r i a l . The petroleum ether soluble p o r t i o n was concentrated under vacuum. A f t e r column chromatography (50% e t h y l acetate/chloroform) 53 mg (23%) of 3a,5,8,8a-tetrahydro-8a-hydroxy-4(lH)-azulenone (132) was obtained as a c o l o r l e s s l i q u i d ; i r (film) 2.88 (m, OH), 5.88 (s, C=0) u; nmr (CDC1 3) T 4.2 (m, 4, v i n y l H), 6.2 (broad s, 1, C^-CH) , 6.8 (d, 2, J = 4 Hz, (C(5)-CH 2-), 7.4-7.7 (m, 5); uv max 290 nm (E 98); mass spectrum (70 eV) m/e parent 164. Hydrogenation of 3a,5,8,8a-Tetrahydro-8a-hydroxy-4(lH)-azulenone (132) A s o l u t i o n of 53 mg (0.32 mmol) of 132 i n 10 ml of et h y l acetate was hydrogenated using 4 mg of platinum oxide as a c a t a l y s t . A f t e r 3 hr, t i c (50% e t h y l acetate/chloroform) showed that a l l the s t a r t i n g materials had been converted i n t o one hydrogenated product with an value s l i g h t l y greater than the one of the s t a r t i n g m a t e r i a l . A f t e r concentration i n vacuo, 53 mg (0.32 mmol, >99%) of octahydro-8a-hydroxy-4(lH)-azulenone (134) was obtained as a c o l o r l e s s l i q u i d , i r (film) 2.91 (s, OR), 5.90 (s, C=0) y; nmr (neat) T 6.8 (d of t, 1, J . = d 2 Hz, J t = 7 Hz, -C0-C(3a)H, bridgehead), 7.5 (m, 2,-C(5)H 2-C0-), 7.8-8.6 Cm, 13). The presence of a hydroxyl proton was v e r i f i e d by the d i l u t i o n technique. - 65 -Dehydration of 0ctahydro-8a-hydroxy-4(lH)-azulenone (134) A s o l u t i o n of 35 mg (0.21 mmol) of 134 i n 5 ml of aqueous methanol containing about 10 mg of potassium carbonate was refluxed f o r 0.5 hr. Thin layer chromatography (50% e t h y l acetate/chloroform) showed one dehydrated product with a greater value than s t a r t i n g material.. The r e a c t i o n mixture was extracted with chloroform and a f t e r concentra-t i o n of the organic layers i n vacuo, 17 mg (0.11 mmol, 50%) of 2,3,5,6,7,8-hexahydro-4(lH)-azulenone (84) was i s o l a t e d as a c o l o r l e s s l i q u i d ; i r (film) 6.03 (s, C=0), 6.07 ( s ) , 6.14 (s) y; nmr (CDC1 3) x 7.4 (m, 8, -CH2C0- and a l l y l i c -CH 2-), 8.2 (m, 6, -CH 2~); uv max 252 nm 62 (calculated according to the Woodward rules 249 nm). This azulenone 29 was prepared independently following a known procedure (see below) and the i r spectra of the two independently synthesized azulenones were superimposable. Hydrogenation of cis,cis-Cyclodeca-3,8-diene-l,6-dione . (82) A s o l u t i o n of 227 mg (1.38 mmol) of c i s , c i s - d i k e t o n e 82 i n 20 ml of e t h y l acetate was subjected to hydrogenation using 4 mg of platinum oxide as a c a t a l y s t . Hydrogen take-up was 60 ml corresponding to 97% of the t h e o r e t i c a l amount. A f t e r f i l t r a t i o n of the re a c t i o n mixture and concentration under vacuum 226 mg (1.36 mmol, 99%) of crude cy c l o -deca-1,6-dione (83) was i s o l a t e d . R e c r y s t a l l i z a t i o n from ethanol gave 120 mg (53%) of J53 as c o l o r l e s s c r y s t a l s . Thin layer chromatography (60% ether/hexane) showed one pure compound. - 66 -2,3,5,6,7,8-Hexahydro-4(IH)-azulenone (84) 27 The procedure of Cope was followed. A s o l u t i o n of 120 mg (0.71 mmol) of cyclodeca-1,6-dione (83) i n aqueous methanol containing about 10 mg of potassium carbonate was refluxed f o r about 1 hr. The r e a c t i o n mixture was extracted three times with chloroform and the combined organic layers were drie d and concentrated to leave 70 mg (0.47 mmol, 66%) of a s l i g h t l y yellow l i q u i d 84. The i r spectrum was superimposable with that of the azulenone obtained by dehydration of 134 (see above). Thermolysis of cis,trans-Cyclodeca-3,8-diene-l,6-dione (112) A s o l u t i o n of 233 mg (1.42 mmol) of 112 i n 10 ml of xylene (bp 138-139°) was sealed i n a Pyrex tube under atmospheric pressure. I t was thermolyzed i n a sublimation apparatus for f i v e days at 192°. The r e s u l t i n g dark brown s o l u t i o n was concentrated under vacuum and checked by glpc (column D, 170°). Most of the s t a r t i n g m a t e r i a l had reacted and three products (128, 129 and 130 i n the order of i n c r e a s i n g r e t e n t i o n time) had been formed i n a r a t i o of approximately 6:3:1. They were c o l l e c t e d by glpc (column D, 150°). Compound 128 gave 18 mg of c o l o r l e s s c r y s t a l s ; mp 125°; i r (CHC1 3) 5.72 (s, C=0), 5.95 (s, C=0) u; nmr CCDC13) T 2.98 (d of d, 1, = 10 Hz, J " 2 = 2 Hz), 4.00 (d of d, 1, J± = 10 Hz, J 2 = 3Hz), 7.0-8.3 (complex m, 9), 8.83 (d, 3, J = 6 Hz);' uv max 226 nm ( e 14,000); mass spectrum (70 eV) m/e 45(100), 81(79), parent 164(24), 211(2). Anal. Calcd. f o r C 1 0 H 1 2 ° 2 : C ' 7 3 , 1 4 ; H » 7 , 3 7 * F o u n d : c» 71.65; H, 7.22 (error f o r C: 2.04%, for H: 2.04%). - 67 -Compound 129 was obtained as a c o l o r l e s s l i q u i d , 10 mg; i r (film) 5.74 (s, C=0), 5.97 (s, C=0) y; nmr (CDC1 3) T 2.8-3.5 (complex m, 1), 4.0 (d of t, 1, J D = 10 Hz, J = 3 Hz), 7.0-8.3 (m, 7), 8.75 and 8.82 (2d, 3, J 1 = J 2 = 6 Hz); mass spectrum (70 eV) m/e 81(100), parent 164(49), 181(7). Only 3 mg of 130 could be c o l l e c t e d as a c o l o r l e s s l i q u i d ; nmr (CDC1 3) T 3.9 (m, 1), 7.0-8.0 (m, 12), 8.8 (d, 3, J = 6 Hz). Photolysis of cis,trans-Cyclodeca-3,8-diene-l,6-dione (112) at 77°K The solvent chosen f o r t h i s photolysis was EPA, a mixture of ether, isopentane, and ethanol i n a r a t i o of 5:5:2 which freezes as a glass at the temperature of l i q u i d nitrogen. Because of s o l u b i l i t y problems l e s s polar solvents could not be used. A mixture of isopentane/n-pentane (5:2, freezes as a glass) and pure Freon 12 ( d i c h l o r o d i f l u o r o -methane) had been t r i e d but the d i s s o l v e d diketone 112 p r e c i p i t a t e d at 77°K i n the pentane mixture and was hardly soluble i n Freon 12 even close to the l a t t e r 1 s b o i l i n g point at -33°. The s o l u t i o n s t r i e d were 0.02 M i n the case of Freon 12 and 0.0024 M i n the pentane mixture. A s o l u t i o n of 40 mg (0.24 mmol) of 112 i n 100 ml of EPA was degassed f o r 15 min and photolyzed i n a large Pyrex f i n g e r (used as a cool trap f o r vacuum pumps). The immersion w e l l containing a Pyrex f i l t e r was equipped with the 200 ml p h o t o l y s i s f l a s k and the whole set-up i n c l u d i n g the external Pyrex f i n g e r was immersed i n l i q u i d nitrogen. Gaseous nitrogen was flushed through the 200 ml f l a s k attached to the immersion well i n order to prevent water from the a i r to condense and freeze on the f l a s k w a l l s . Furthermore the gaseous nitrogen prevented - 68 -the cooling water from f r e e z i n g . The reaction was followed by glpc (column A, not acid washed, 135°) and t i c (chloroform/ether 1:1). A f t e r 8 hrs about 10% of the t r i c y c l i c ketone 122 and about 5% of c i s , c i s - d i k e t o n e 82 were formed according to the re t e n t i o n time of the gas chromatogram, checked by coir i j e c t i o n of authentic 122 and j3_2. The t h i n l a y e r chromatogram showed the two spots corresponding to 122 and 82. Photolysis of 112 i n EPA at Room Temperature A s o l u t i o n of 17 mg (0.104 mmol) of 112 i n 43 ml of EPA was degassed and photolyzed i n the same set-up used f o r the pho t o l y s i s at 77°K. A f t e r 1 hr about 10% of 112 had reacted to give the t r i c y c l i c diketone 122 according to glpc (same conditions as i n the 77°K p h o t o l y s i s ) . No c i s , c i s diketone j52_ could be observed by glpc. 2 6 Dipole Moment of c i s , a n t i , c i s - T r i c y c l o I 5 . 3 . 0 . 0 " ]decane-4,9-dione This measurement was c a r r i e d out i n the laboratory of Professor 52 N.L. A l l i n g e r of the Un i v e r s i t y of Georgia, u = 1.45 ± 0 . 3 (25°C; solvent:benzene). 2 6 Raman and Infrared Spectra of c i s , a n t i , c i s - T r i c y c l o [ 5 . 3 . 0 . 0 ' Jdecane-4,9-dione The Raman spectrum of a c r y s t a l of the t r i c y c l i c diketone was o obtained with a Cary Model 81 Raman spectrophotometer, using the 6328 A 61 —1 e x c i t i n g l i n e of a helium neon l a s e r . Accuracy: ±2-3 cm - 69 -The i r spectrum was recorded on a Perkin-Elmer Model 21 double Beam Infrared Spectrophotometer. (Accuracy: at 4000 cm *: +20 cm *; at 650 cm *: ±1.5 cm * ) . Raman r - 1 ! [cm ] 339 439 457 480 554 638 749 790 826 879 IR [cm 1 ] 287 429 472 620 683 748 792 825 850 927 950 Raman [cm l ] 1005 1024 1060 1083 1142 1243 1329 1354 1402 IR [cm ] 1002 1028 1076 1116 1136 1150 1166 1240 1252 1268 1290 1328 1360 1393 1718 1729 - 70 -BIBLIOGRAPHY 1. S. Bodforss, Chem. Ber., 51, 214 (1918). 2. H.E. Zimmermann, B.R. Cowley, C.-Y. Tseng, and J.W. Wilson, J. Amer. Chem. Soc., 86, 947 (1964). 3. C.K. Johnson, B. Dominy, and W. Reusch, i b i d . , 85, 3894 (1963). 4. C.S. Markos and W. Reusch, i b i d . , 89, 3363 (1967). 5. C. Walling i n P. de Mayo "Molecular Rearrangements," Interscience Publishers, Inc., New York, N.Y., 1963, Chapter 7. 6. H.E, Zimmermann and A. Zweig, J . Amer. Chem. Soc., 83, 1196 (1961). 7. M.S. Kharash, A. Fono, and W. Nudenberg, J . Org. Chem.,16, 113 (1951). 8. F.D. Greene, W. Adam, and G.A. Knudsen, J r . , i b i d . , 3 1 , 2087 (1966). 9. H. Wehrli, C. Lehmann, T. Iizuka, K. Schaffner, and 0. Jeger, Helv. Chim. Acta, 50, 2403 (1967). 10. W. Reusch, D.F. Anderson, and C.K. Johnson, J . Amer. Chem. S o c , 90, 4988 (1968). 11. (a) H. Wehrli, C. Lehmann, P. K e l l e r , J . Bonet, K. Schaffner, and 0. Jeger, Helv. Chim. Acta, 49, 2218 (1966); (b) f o r a review on the photochemistry of s t e r o i d a l a,3-epoxy ketones see 0. Jeger, K. Schaffner, and H. Wehrli, Pure Appl. Chem., 9_, 555 (1964). 12. H.E. Simmons and T. Fukunaga, J . Amer. Chem. Soc., 89, 5208 (1967). 13. K. Nakanishi, "Infrared Absorption Spectroscopy", Holden-Day, Inc., San Francisco, 1962; 14. H. Gerlach, Helv. Chim. Acta, 51, 1587 (1968). 15. D.J. Cram and H. Steinberg, J . Amer. Chem. Soc., 76, 2753 (1954). - 71 -16. H. Hart and L.R. Lerner, J . Org. Chem., 32, 2669 (1967). 17. The author g r a t e f u l l y acknowledges a g i f t of t h i s compound by J. Balf of t h i s department. 18. J . Reese, Chem. Ber., 75, 384 (1942). 19. R.L. Wasson and H.O. House, Org. Synth., 37, 58 (1957). 20. J.-L. P i e r r e , Ann. Chim., 159 (1966). 21. H.O. House and R.L. Wasson, J . Amer. Chem. Soc., 78, 4394 (1956). 22. H.C. Brown, J.H. Brewster and H. Schechter, i b i d . , 76, 467 (1954). 23. R. B a l t z l i , E. Lorz, P.B. R u s s e l l , and F.M. Smith, i b i d . , 77, 624 (1955). 24. G. LeGuillanton, B u l l . Soc. Chim. France, 611 (1963). 25. M.E. Cain, J . Chem. S o c , 3532 (1964). 26. H.B. Henbest, Proc. Chem. S o c , 159 (1963). 27. J.C. C o l l i n s , W.W. Hess, and F.J. Frank, Tetrahedron L e t t . , 3363 (1968). 28. (a) C A . Grob and P.W. Schiess, Helv. Chim. Acta. , 43, 1546 (1960); (b) K. Grohmann and F. Sondheimer, Tetrahedron L e t t . , 3121 (1967). 29. A.C. Cope and G. Holzman, J . Amer. Chem. Soc., 72, 3062 (1950). 30. R. Srinivasan and K.H. Carlough, i b i d . , 89, 4932 (1967); 30a. (a) R.C. Cookson, Quart. Rev.,22, 423 (1968); (b) J.R. Scheffer and R.A. Wostradowski, J . Chem. S o c , (D), 144 (1971). 31. R.S.H. L i u and G.S. Hammond, i b i d . , 89, 4936 (1967). 32. K.J. L a i d l e r , "Chemical K i n e t i c s , " 2nd ed., McGraw-Hill Book Co., Inc., New York, N.Y.., 1965, pp 166-167. 33. J.D. White and D.N. Gupta, Tetrahedron, 25, 3331 (1969). 34. R.C. Lamb, P.W. Ayers, and M.K. Toney, J . Amer. Chem. Soc., 85, 3483 (1963). - 72 -35. (a) S. Moon and C.R. Ganz, Tetrahedron L e t t . , 6275 (1968); (b) G.M. Whitesides, G.L. Goe and A . c . Cope, J . Amer. Chem. Soc., 91, 2608 (1969). 36. J.R. Scheffer and M.L. Lungle, Tetrahedron L e t t . , 845 (1969). 37. C H . Heathcock and R.A. Badger, Chem. Comm. , 1510 (1968). 38. J.R. Scheffer and B.A. Boire, Tetrahedron L e t t . , 4005 (1969). 39. M.L. Lungle, M.Sc. Thesis, U n i v e r s i t y of B r i t i s h Columbia, 1969. 40. R.B. Woodward and R. Hoffmann, Angew. Chem. , Int. Ed. Engl. , JJ, 781 (1969). 41. (a) H.L. C a r r e l l , B.W. Roberts, J . Donohve, and J . J . Vollmer, J . Amer. Chem. Soc., 90, 5263 (1968); (b) B.W. Roberts, J . J . Vollmer, and K.L. S e r v i s , i b i d . , 9 0 , 5264 (1968). 42. A. Shani, Tetrahedron L e t t . , 5175 (1968). 43. J.W. Stankorb and K. Conrow, i b i d . , 2395 (1969). 44. H. Z i f f e r and I.W. Levin, J . Org. Chem., 34, 4057 (1969). 45. J.G. Calvert and J.N. P i t t s , J r . , "Photochemistry", John Wiley & Sons, Inc., New York, second p r i n t i n g , 1967, p. 298. 46. H.E. Zimmermann and J.S. Swenton, J . Amer. Chem. S O c , 89, 906 (1967). 47. H.M.R. Hoffmann, Angew. Chem., Int. Ed. Engl., _8, 556 (1969). 48. R.C. Cookson and S. MacKenzie, PrOc. Chem. SOc., London, 423 (1961). 49. E.N. Marvell and W. Whalley, Tetrahedron L e t t . , 1337 (1969). 50. H.M. Frey, Advan. Phys. Org. Chem. , 4_, 148 (1966). 51. J . Dale and C. Moussebois, J . Chem. Soc. (C), 264 (1966). 52. The author i s indebted to Prof. N.L. A l l i n g e r f o r car r y i n g out the dipole measurement. - 73 -53. A.L. McClellan, "Tables of Experimental Dipole Moments", W.H. Freeman and Company, San Francisco, 1963. 54. V.I. Minkin, O.A. Osipov, and Y.A. Zhdanov, "Dipole Moments i n Organic Chemistry", Plenum Press, New York, 1970. 55. S. Sasson, I. Rosenthal, and D. Elad, Tetrahedron L e t t . , 4513 (1970) 56. O.L. Chapman, P.J. Nelson, R.W. King, D.J. Trecker, and A.A. Griswold, Record Chem. Progress, 28, 167 (1967). 57. R.P. Baumann, "Absorption Spectroscopy", John Wiley & Sons, Inc., New York, N.Y., 1962, p. 462. 58. A.C. Cope and W.R. Schmitz, J . Amer. Chem. Soc., 72, 3056 (1950). 59. W. Huckel, M. Maier, E. Jordan and W. Seeger, Justus Li e b i g s Ann. Chem., 616, 68 (1958). 60. G.I. Poos, G.E. A i t h , R.E. Beyler, and L.H. S a r r e t t , J . Amer. Chem. S o c , 75, 425 (1953). 61. The author i s very much indebted to Dr. A. Bree of t h i s department f o r the recording of a Raman spectrum. 62. I. Fleming and D.H. Williams, "Spectroscopic Methods i n Organic Chemistry", McGraw-Hill Publishing Company Limited, London, 1966, p. 23. 

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