Efficient Construction of the Clerodane Decalin Core by an Asymmetric Morita-Baylis-Hillman Reaction/Lewis Acid Promoted Annulation Strategy

摘要

The clerodane class of natural products are diterpenes that exhibit wide-ranging structural diversity.[1] Over 150 new bioactive clerodanes have been reported since 2002.[2] Of particular interest are asmarines A (1) and B (2)[3] and popolohuanone E (3),[4] members of this class of naturalproducts that exhibit potent antiproliferative activity against several types of human-cancer-cell lines (Scheme 1). Popolohuanone E is a topoisomerase II inhibitor,[4] whereas the biological target of asmarine A or B is not known. Given their biological activity and the prevalence of the structural motif they display, a general and efficient strategy towards the core structure of the clerodane would be attractive.