Total Synthesis of Aquatolide.

ABSTRACT

A total synthesis of the sesquiterpene lactone aquatolide has been accomplished. The central step is an intramolecular [2 + 2]-photocycloaddition of an allene onto an α,ß-unsaturated δ-lactone. Other key steps are an intramolecular Horner-Wadsworth-Emmons reaction to close the lactone and an intramolecular Mukaiyama-type aldol reaction to cyclize the eight-membered ring. Racemic aquatolide has been resolved using preparative HPLC.