Diastereoselective and enantioselective epoxidation of acyclic β-trifluoromethyl-β,β-disubstituted enones by hydrogen peroxide with a pentafluorinated quinidine-derived phase-transfer catalyst

An efficient catalytic asymmetric epoxidation of β-trifluoromethyl- β,β-disubstituted unsaturated ketones has been achieved by a pentafluorine-substituted phase-transfer catalyst with hydrogen peroxide (30%). Thus, the β-trifluoromethyl-α,β-epoxy ketones with a quaternary carbon centre were obtained in excellent diastereoselectivities (up to 100:1 dr) and excellent enantioselectivities (up to 99.7% ee). Low catalyst loading, recycle of catalyst, environmentally benign oxidant and easy transformation of the epoxides into medicinally important trifluoromethylated intermediate make our protocol much more practical.