Catalytic asymmetric epoxidation of enones under phase-transfer catalyzed conditions

The development of the catalytic asymmetric epoxidation of enones promoted by aqueous H2O2 with chiral quaternary ammonium salts is described. The reaction smoothly proceeded to give α,β-epoxyketones with satisfactory enantioselectivities in both the trans and cis enone systems (up to 92% ee) by use of cinchonine or quinidine derivatives (5 mol%) as phase transfer catalysts.