Ginkgolides: selective acetylations, translactonization, and biological evaluation.

Protocols for selective acetylation of the hydroxyl groups of ginkgolide C have been developed. These acetylations have given rise to various ginkgolide C acetates and iso-ginkgolide C acetates, the latter having a rearranged skeleton resulting from translactonization. These acetyl derivatives, as well as ginkgolides A and B acetates have been investigated for their ability to bind to a cloned platelet-activating factor (PAF) receptor.