First enantioselective total synthesis of (natural) (+)-11,12-epoxy-11,12-dihydrocembrene-C and (−)-7,8-epoxy-7,8-dihydrocembrene-C

Abstract

The first enantioselective total syntheses of (+)-11,12-epoxy-11,12-dihydrocembrene-C 1 and (−)-7,8-epoxy-7,8-dihydrocembrene-C 2, two naturally occurring cembranoxides isolated from tropical marine soft corals, are achieved via a general approach by employing an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as key steps from readily available starting materials. The syntheses presented here verify the absolute stereochemistry assignment of 1 as (11S,12S) by Bowden et al. two decades ago, and the epoxy configuration of 2 was assumed as (7R,8R) accordingly.