Abstract: The asymmetric epoxidation of styrene included by cyclodextrins with dioxirane produced in situ from ketones and potassium peroxymonosulfate (Oxone) was achieved. The effects of different cyclodextrins and ketones on the epoxidation of styrene were investigated, and the possible mechanism for the synergistic catalysis of cyclodextrins and ketones was suggested. The results indicated that β-cyclodextrin had good ability of chiral recognition to dioxirane that was generated in situ from methyl isobutyl ketone (MIBK) and Oxone. Various factors, such as molar ratio of MIBK to cyclodextrin inclusion complex, NaHCO3 amount, reaction time, and reaction temperature, that affected the enantiometric excess of the reaction products were examined, and the maximum enantiometric excess of1,2-epoxyethylbenzene was up to 46% under the optimal reaction conditions.

Key words: styrene, cyclodextrin, inclusion complex, dioxirane, epoxidation, synergistic catalysis, epoxyethylbenzene