Oxidative functionalisation of SuperQuat enamides: Asymmetric synthesis of homochiral 1,2 diols

Homochiral (E)-enamides derived from (S)-4-phenyl-5,5-dimethyl-oxazolidin-2-one undergo highly diastereoselective epoxidation upon treatment with dimethyldioxirane (DMDO). Treatment with m-chloroperbenzoic acid (MCPBA) produces syn-(4S, 1'R,2'S)-1'-acyloxy-2'-hydroxy derivatives with high diastereoselectivity, consistent with a mechanism involving initial epoxidation and subsequent in situ S, I type epoxide opening and trapping with in-chlorobenzoic acid. Reductive cleavage of the isolated 1'-acyloxy-2'-hydroxy derivatives generates 1.2-diols in high yields and in high ee.