Catalytic Enantioselective α-Ketol Rearrangement

A highly enantioselective alpha-ketol rearrangement has been developed. In the presence of a chiral Cu-bisoxazoline complex, achiral beta-hydroxy-alpha-dicarbonyls were isomerized to chiral alpha-hydroxy-beta-dicarbonyls and their bicyclic derivatives in excellent yields and enantioselectivities. Enantioenriched 2-acyl-2-hydroxy cyclohexan-1-ones, dihydroxyhexahydrobenzofuranones, and dihydroxyhexahydro-cycloheptafuranones, with up to three stereocenters, were readily prepared from achiral starting materials in one operation. The reaction is applicable to the desymmetrization of meso substrates and kinetic resolution of racemic alcohols.