Catalytic Enantioselective Pinacol and Meinwald Rearrangements for the Construction of Quaternary Stereocenters

摘要

The development of enantioselective pinacol rearrangement is extremely challenging due to the likelihood involvement of the carbenium intermediate that renders the stereochemical communication between catalyst and substrate difficult to achieve. Herein, we report chiral N-triflyl phosphoramide-catalyzed enantioselective pinacol rearrangement of 1,2-tertiary diols and mechanistically related Meinwald rearrangement of tetrasubstituted epoxides for the synthesis of enantioenriched 2-alkyny1-2-arylcyclohexanones and 2,2-diarylcyclohexanones, respectively. Total synthesis of (+)-mesembrane featuring the catalytic enantioselective pinacol rearrangement as a key strategic step is also documented.