Stereochemistry of some reactions of ring D of the diterpenoid aphidicolin

Abstract

The stereochemistry of a number of reactions at C-16 in the diterpenoid, aphidicolin, has been examined, and, unlike simpler bicyclo[3.2.1]octane derivatives, there is only a limited degree of stereospecificity. The 15-enes can be prepared by dehydration of the epimeric 16-alcohols. Epoxidation and catalytic reduction have been shown to occur from the β-(exo)-face of the bicyclo[3.2.1]octene system that constitutes rings C and D of the aphidicol-15-enes. The stereochemistry or aphidicolane-3α,16α,18-triol has been established by X-ray crystallography.