Asymmetric total synthesis of (+)-propolisbenzofuran B

Abstract

The first asymmetric total synthesis of (+)-propolisbenzofuran B is accomplished in 11 steps with an overall yield of 11.9%. The key steps are tandem deacetylative Sonogashira coupling-annulation reaction to synthesize the 2-substituted benzofuran core, stereoselective syn-aldol reaction and Friedel–Crafts cyclization to install the desired stereocenters & third-ring, and Stille coupling for C-acetylation.