树兰烯((王古)(王巴)烯)类似物的合成

Synthesis of Analogs of Aglaiene (Copaene)

本文报道了树兰烯(即(王古)(王巴)烯)的几个类似物(6a-d和7a-d)的合成,并讨论了有关这些化合物的形成反应的构象效应。

Ten analogs (6a—d and 7a—d) of aglaiene (copaene, 1) have been synthesized follow the main steps of Heathcock using 3-methyl Wieland ketone (3a) and Wieland ketone (3b) as the starting materials. It has demonstrated that the formation of the endocyclic and exocyclic double bond isomers (6 and 7) was in accord with the contribu- tion of the conformers of the tertiary alcohol (14) as expected, i.e., the major product 6 formed from the preferred conformer 14A with an axial OH group, and the minor product 7 formed from the conformer 14B with an equatorial OH group. While the content of the E-Z isomers(E-7 and Z-7) formed did not follow conformational analysis so regularly. The direction of the reaction of the alcohol with an i-butyl group (14c), but not the one with a n-butyl group (14d), can be correctly predicted. Some other factors may exist to influence the conformational distribution of the B' and B' of 14d, and consequently, the amounts of E-7d and Z-7d cannot te estimated. On the other hand, in 14c, the conformational effect of the i-butyl group is strong enough to cause the effect of these factors unnoticeable.