A-Caryophyllene alcohol

Analysis TM290 was used by Corey ( . Amer. Chem. Soc,, 196, 86, 1652) in his synthesis of a-caryophyllene alcohol. Again, only one disconnection is very productive ... 

Though the rearrangement step transforms a stable tertiary cation into a less stable secondary cation, relief of strain in expansion from a four- to a five-membered ring makes the alkyl migration favourable. In 1964, E.J. Corey published a synthesis of the natural product a-caryophyllene alcohol that made use of a similar ring expansion. Notice the photochemical [2+2] cycloaddition (Chapter 35) in the synthesis of the starting material. 

Other products which were isolated from this study were the related fused 5,7-ring molecules (117)-(119), together with a-caryophyllene alcohol (116 Scheme 13). 

The ready availability of four-membered rings of defined stereochemistry from enone-alkene photocycloadditions has been the origin of several syntheses which employ Wagner-Meerwein rearrangements in subsequent steps. This is exemplified by a neat and very short synthesis of a-caryophyllene alcohol (40) from cyclopentene and 3-methylcyclohexenone which was described some years ago (see Scheme 15). The rearrangement in 40% sulfuric acid proceeded remarkably smoothly. A short synthesis of iso-comene (41 Scheme 16) also Illustrates this strategy... 

These compounds co-occur in the essential oil of Cedrus atlantica and it is interesting to note that a-caryophyllene alcohol (62) (obtained for the first time as a natural product) and the epimeric himachalene epoxides (63 a and b) have also been identified as co-metabolites. ... 

This ring-expansion process is quite useful when applied to polycyclic systems. Corey treated 57 with 40% sulfuric acid and isolated the rearranged alcohol, a-caryophyllene alcohol (60). The initially formed cyclo-butylcarbinyl cation (58) rearranged to the cyclopentyl cation (59), which was trapped by water to give 60. 

Synonyms a-Caryophyllene alcohol Decahydro-2,2,4,8-tetramethyl-4,8-methanoazulen-9-ol... 

In dioxan-water containing 0.02 mol 1 perchloric acid, humulene is hydrated to humulol (256) which then rearranges to give a-caryophyllene alcohol (257 20—25 %) and a mixture of bicyclo[5,3,0]decenes (75 %) of which (258 90% of the mixture) is the major component. Mechanisms for these rearrangements were proposed based on... 

C2iH280sr Dihydrodesacetoxyglaucolide-A, 40B, 514 C2iHjsBrNjOaS, Acorone p-bromophenylsulphonylhydrazone, 31B, 216 C2iH2sBr03S, a-Caryophyllene alcohol p-bromobenzenesulphonate, 35B, 386... 

CHAlUHGtl Humulene and a-caryophyllene alcohol are terpene constituents of carnation extracts. The former is converted into the latter hy acid-catalyzed hydration in one step. Write a mechanism. (Hint The mechanism includes cation-induced double-bond isomerization, cyclizations, and rearrangements that may involve hydrogen and alkyl-group migrations. Two of the intermediates in the mechanistic sequence are shown five carbon atoms are identified by starts to help you track their positions through the process.)... 

CHAiUNCt CaryophyUene (C15H24) is an unusual sesquiterpene familiar to you as a major cause of the odor of cloves. Determine its structure from the following information. (Caution The structure is totally different from that of a-caryophyllene alcohol in Problem 72.)... 

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