Improved procedure for the room temperature asymmetric phase-transfer mediated epoxidation of α,β-unsaturated ketones

Studies into the factors affecting the rate of reaction in the enantioselective epoxidation of α,β-unsaturated ketones utilising Cinchona alkaloid-derived quaternary ammonium phase-transfer catalysts are reported. This has led to the identification of improved conditions for the room temperature epoxidation process, which require only 1 mol% catalyst and lead to isolation of the epoxide products in high enantiomeric excess.