Total synthesis of cyclopentanoid natural products

Abstract

The highly functionalised bicyclo[3.3.0]octanes (5) and (6) have been prepared by a sequence involving intramolecular Wittig reactions of the diketo ester (9) with vinyl phosphonium salts (3) and (4). Compounds (5) and (6) have then been used as starting materials for formal syntheses of (±)-chrysomelidial, (±)-loganin, and (±)-hirsutene. An intermediate used in the synthesis of (5) and (6) has been converted into a known precursor of (±)-sarkomycin.