3Z-Cembrene

A classic method for preparing macrocyclic rings is ring expansion. Wender et al. have used this technique to synthesize (—)-3Z-cembrene A (159) (Scheme 6-12). - ... 

A full paper on the isolation of cembrene-A (64) and (3Z)-cembrene A from a termite soldier, Cubitermes umbratus, has appeared. An 11,12-epoxycem-brene (65), which has been extracted from Greek tobacco, may act as a biogenetic precursor of some of the 8,11- and 8,12-epoxycembranoids which are also found in tobacco. 

Scheme 7.35 Possible mechanism for reductive rearrangement of propargylic chlorohydrins. 7.S.2.2 (-)-(3Z)-Cembrene A (Wender)...

The availability of the triene (108) prompted the preparation of all m-cembrene A (110) which was achieved by standard methods. Thus, five of the eight possible 3,7,11,15-cembratetraenes have been prepared. Of these, the 3 ,7 ,11 ,15- and the 3Z,7 ,11 , 15-isomers have been found as natural products and prepared by synthesis. The 3 ,7Z,11 ,15-, 3 ,7 ,11Z,15- and the 3Z,7Z,1 lZ,15-isomers have been synthesized only (16). 

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