A Formal Synthesis of Psymberin

Significance

Psymberin is the most selective antitumor agent of the 33 members of the pederin family of sponge metabolites. The salient step of the synthesis depicted is a chemo- and stereo­selective epoxidation of the scalemic allene D with dimethyldioxirane (DMDO) to give the stable spirodiepoxide E which then rearranged to F on exposure to MeOH.