A highly enantioselective phase-transfer catalyzed epoxidation of enones with a mild oxidant, trichloroisocyanuric acid.

The enantioselective epoxidation can be carried out using trichloroisocyanuric acid (TCCA) as oxidant in the presence of chiral quaternary ammonium salt as a phase-transfer catalyst; treatment of chalcone derivatives with TCCA under mild conditions afforded the corresponding epoxy ketones in good yields with moderate to excellent enantioselectivities of up to 96%.