Synthesis of diospongin A, ent-diospongin A and C-5 epimer of diospongin B from tri-O-acetyl-D-glucal

Abstract

We describe a new synthesis of diospogin A, its enantiomer ent-diospongin A and C-5 epimer of diospongin B from commercially available tri-O-acetyl-D-glucal, based on a copper catalyzed Michael addition of phenyllitium to the corresponding ,-unsaturated ketone. The stereochemical course of the Michael addition was unambiguously established by X-ray crystallographic analysis.