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Redacted for Privacy Elliot N AN ABSTRACT OF THE THESISOF TERRY EARL MC EWEN for the MASTER OF SCIENCE (Name) (Degree) in CHEMISTRY (Organic)presented on May 29, 1968 (Major) (Date) Title: IDENTIFICATION OF A PRODUCTOF THE FRIEDEL- CRAFTS CYCLIZATION OF f3-(3-CYCLOHEXENYL)- PROPIONYL CHLORIDE Abstract approved: Redacted for privacy Elliot N. Marvell An improved procedure for thepreparation of p- (3-cyclo- hexenyl)propionic acid from 4-vinylcyclohexenewas developed.The Friedel-Crafts cyclization of (3- (3- cyclohexenyl)propionylchloride with aluminum chloride was shown to giveone bicyclic chlorine containing ketone in 41% yield.This -ketone was identified by a. combination of spectral and chemical methodsas a mixture of exo- and endo-6-chlorobicyclo[ 3. 3. 1] nonan-2-ones.Useful synthetic procedures for the conversion of this ketone to 6-bicyclo[3. 3. 11 - nonen-2-one and to 2-bicyclo[ 3. 3. 1] nonanolswere developed. A logical route to 6-chlorobicyclo[ 3. 3. 1] nonan-2-onefrom -cyclohexenyl)propionyl chloride must involve Z-oxo-8-bicyclo- [ 3. 3.1 j nonyl carbonium ionas an intermediate.In support of this idea it was shown that 8-chlorobicyclo[ 3. 3. 1] nonan-2-onecan be converted to 6-chlorobicyclo[ 3. 3. 1]no:nan-2-one under the conditions of the Friedel-Crafts cyclization. Identification of a Product of the Friedel-Crafts Cyclization of (3- (3- Cyclohexenyl)propionyl Chloride by Terry Earl McEwen A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science June 19 69 APPROVED: Redacted for privacy Professor of Chemistry in charge of major Redacted for privacy Chairman ofDep.'artment of Chemistry Redacted for privacy Dean of Graduate School Date thesis is presented May Z9, 1968 Typed by Gwendolyn Hansen for Terry Earl McEwen TABLE OF CONTENTS Page INTRODUCTION 1 HIS TORIC AL 2 DISC USSION 7 Determination of the Carbon Skeleton 8 Determination of the Ketone Position 10 Determination of the Chlorine Position 11 EXPERIMENTAL 17 6- (3- Cyclohexenyl)propionic Acid 17 6-Chlorobicyclo[ 3. 3. 1] nonan-2- one: Chloroketone-A 18 Attempted Reductive Dechlorination of Chloroketone-A 19 Palladium on Charcoal 19 Raney-nickel 20 Nickel-aluminum Alloy 21 Sodium Metal 21 2-Bicyclo[ 3. 3. 1] nonene 22 Bicyclo[ 3. 3. 1] nonene 22 2-Bicyclo[ 3, 3. 1] nonanol 23 6-Bicyclo[ 3. 3. 1] nonen-2- one 24 Method A 24 Method B 25 Attempted Dehydrochlorination with Sodium Ethoxide 26 Attempted Preparation of 6-Hydroxybicyclo[ 3. 3. 1]- nonan-2-one 27 Isomerization of 8-Chlorobicyclo[ 3. 3. 1] nonan -2 -one 27 Spectral Measurements 28 Melting Points 28 Elemental. Analysis 28 BIBLIOGRAPHY 29 IDENTIFICATION OF A PRODUCT OF THE FRIEDEL-CRAFTS CYCLIZATION OF 13- (3-CYCLOHEXENYL)PROPIONYL CHLORIDE INTRODUCTION Recent improvement in the understanding of cyclohexane ring chemistry has been mainly due to development ofan effective con- formational analysis of cyclohexane derivatives.An equivalent understanding of medium ring chemistry has been limited by the conformational mobility of these rings. Aprogram aimed at using bridged medium rings as conformationally restricted models for medium rings has been underway at Oregon State for severalyears. For this purpose the synthesis of bicyclo[ 3. 3. 1]nonane derivatives, especially those containing functionalgroups in both rings, has been investigated.It had been found previously in our laboratory that at least seven different productscan be obtained from the Friedel-Crafts cyclization of p- (3-cyclohexen.yl)propion.y1 chloride depending on the temperature, the catalyst and the solvent used,Only one of the seven, 7-bicyclo[3. 3. 1] nonen-2-one, had been completely identified when this work was initiated.Cyclization in 1, 2- dichloroethane at room temperature with aluminum chloride as the catalyst gave one major product in 41% yield.The identification of this compound as 6-chlorobicyclo[ 3. 3. 1] nonan-2-one is the subject of the research described in this thesis, 2 HISTORICAL The Friedel-Crafts reaction hasa long history of successful use in synthesis.The intramolecular reaction of acyl halideswith aromatic substituents appropriately placedon the alipatic chain has been one step of the standard routesto annellation of fused ring systems.Similarly the internal acylation ofan unsaturated acid chloride constitutes a useful route to alicyclicmolecules.1 The first such reaction was described in 1935 byCook and Lawrence (5) who prepared A9,10-1-octalone (III) from y-(1-cyclo- hexenyl)butyryl chloride (I) using stannic chloridein carbon disul- fide.The Friedel-Crafts reactionwas followed by dehydrochlorina- tion of the intermediate.Presumably the initial product of the reaction was 5- chloro- 1- decalone (II). Citronellic acid chloride (IV) has also been cyclized under these same conditions to give, after dehydrochlorination,the terpene pulegone (V) (3) 0 0 II II SnC1 PhNMe 4 > 2 Cl I II III 1For a review of intramolecular acylation, see G. A. Olah, ed. "Friedel-Crafts and Related Reactions," Vol IIIpart 2, Interscience Publishers, John Wiley and Sons, Inc., New York, N. Y. ,1964. pp.10 54-10 69. 3 1. S nC1 4 CO Cl 2. KOH/Methanol / I\ IV In 1953 Mathieson (20) prepared ethyl 4, 5, 6, 7-tetrahydro-3- oxoindane-l-carboxylate (VII) by treating p-carbethoxy-p-cyclo- hexenylpropionyl chloride (VI) with stannic chloride in 1, 2- dichloroethane. In a similar manner, Plattner and Bachi (28) cyclized p- carbethoxy-P-cycloheptenylpropionic acid (VIII) with zinc chloride and obtained the unsaturated ketone X after hydrolysis of the inter- mediate keto ester VIV. SnC1 4 COOCHCH3 COO CHCH3 2 2 VI VII Zn CI 2 H Cl COO CHCH COO CHCH 2 3 2 3 VIE VIX X Another intramolecular acylation resulted when 13- (3-cyclo- liexcnyl)propionyl chloride (XI) was treated with stannic chloride in chloroform.In this case the product was shown to be 7-bicyclo- 3. 3. 1] nonen-2-one (XII),However, treatment of the free acid 4 with polyphosphoric acid gave 4,5, 6, 7-tetrahydroindanone(XIV) in 74% yield (30). XI XII XIII XIV Erman and Kretschmer (8) have recently shown (1968) that treatment of the acid chloride XV with aluminum chloride in diglyme at 100'C for 16 h.rs resultsin a 26% yield of exo-2- chlorobicyclo[ 3. 3. 1] nonan-9- one (XVI). cool Al C13 Cl XV XVI As the preceding examples have shown, the interaction of the olefin and the electrophilic acyl species results inan intermediate which can either add a halide ion to producea p-haloketone or eliminate a p-proton to produce an unsaturated ketoneAnother possibility, first observed by Nenitzescu and Gava't in 1935 (22) is a hydride shift.These workers noticed that in the aluminum 5 chloride catalyzed reaction between acetyl chloride,cyclohexene, and benzene in carbon disulfide the expectedl-acetyl-2-phenyl- cyclohexane was not formed,Instead, the 4-phenyl isomer was obtained in 34% yield.No trace of other isomeric phenylacetyl- cyclohexanes was found. Hydride shifts are also indicated by the detection ofisomeric chloroketones formed during Friedel-Crafts acylations.For example, the reaction of cyclohexene with benzoylchloride in the presence of aluminum chloride results in a 5% yield of 4-chloro- benzoylcyclohexane (33).Furthermore, the 2-chlorobenzoylcyclo- hexane expected as a normal product of this reaction hasbeen shown to isomerize to the 4-chloro isomer under the reaction conditions (33). 0 COQ Al C13 11 Cl C 0 C Cl Nenitzescu and coworkers (2.5) have studied the products arising from aluminum chloride catalyzed acetylation ofa variety of cyclic olefins,Chloroketones were formed in good yield with chlorine being found in either f3 or y positions.With cyclopentene for example 96% of the chlorine appeared in they position and only 4% at the 3 carbon, 6 In general it seems that the migrating group terminates at a secondary carbon atom that is as far removed from the inductive influence of the carbonyl group as possible.Even a tertiary carbon atom does not halt this migration.Thus the aluminum chloride catalyzed reaction between 3-methyl -2-hexen-l-oic acid (XVII) and benzene produces 5-phenyl -3-methylcaproic acid (XVIII) (23). GH CH3 3 AlC1 3 CH(CH 2)2C = C HC 00H ' > CH -CHCH CH-CHCOOH 3 2 XVII XVIII In order to determine how far this migration can be forced along a saturated carbon chain, 2-nonenoic acid was condensed with benzene in the presence of aluminum chloride.Only 8-phenyl- nonanoic acid was obtained (24).Even when oleic acid was con- densed with benzene under these conditions 50% of the product was 17-phenylstearic acid and the remainder of the product consisted of acids with the phenyl group appearing at positions 10-16 (24). 7 DISCUSSION Friedel-Cral s cyclization of 13-(3-cyclohexertyl)propionyl chloride has been found to give a number of products dependingon the catalyst, the solvent and the temperature,Reaction at room temperature with aluminum chloride in 1, -2-dichloroethane is of particular interest 'because one compound comprises about 80% of the monomeric material.This product, having the composition CH OC1 can be isolated in about 40% yield, 913 It will be referred to here as chloroketone-A, The spectral data for chloroketone-A are not sufficient to delineate its structure in the, absence of further information,How- ever, the absence of absorption in the olefinic proton region of the .nmr in conjunction with the elemental composition and the presence of a carbonyl absorption. at 1710 cm-1 confirms the bicyclic nature of the molecule,The carbonyl band at 1710 erti-1 indicates that the ring bearing the ketone must have at least six carbon atoms, Nmr resonance at 4.28 ppm shows that this is a secondary chloride and the chlorine is not alpha to the ketone,Absence of bands in the vrir.vr at hig,her fields than 1,4 ppm suggested the lack of C-methyl ,,..roupsThough high frequency C-H stretching and bending bands :ire not observed this is not indicative since these bands are enerally absent in bicyclo[ 3..3,1] .nonanones,If skeletal 8 rearrangements are excluded, these data limit the possible carbon skeletons to two, viz.
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