Rapid Access to the 'in,out'-Tetracyclic Core of Ingenol

摘要

Ingenol (1),a prototypical diterpene of ingenanes,was first isolated from Euphorbia ingens by Hecker and co-workers.Along with esters of the structurally related phorbol (2),the naturally occurring C3-monoesters of 1 are known to be among the most potent tumor promoters.