An Ireland−Claisen Approach to Lignans: Synthesis of the Putative Structure of 5-epi-Eupomatilone-6

Abstract
A novel Ireland−Claisen approach to the putative structure of eupomatilone-6 is described. The rearrangement established the C3 and C4 stereocenters and concomitantly generated a vinyl epoxide. The C5 oxygen was installed by cyclization of the pentenoic acid carboxyl group onto the vinyl epoxide in an SN2‘ fashion to afford the C5-epi stereochemistry. The natural C5 stereochemistry was accessed via a substrate directed dihydroxylation.