A Nitrone Dipolar Cycloaddition Strategy toward an Enantioselective Synthesis of Massadine

摘要

An enantioselective route to the C,D-bicycle of massadine is reported. Enantiopure intermediates were generated by a single stereoselective reduction using the Corey–Bakshi–Shibata reagent. This initial stereoinduction was translated into the five contiguous stereocenters of the massadine D-ring by a synthetic route that features a diastereoselective and stereospecific Ireland–Claisen rearrangement of a trianionic enolate followed by a diastereoselective nitrone dipolar cycloaddition of a highly electron-poor oxime.