Highly regioselective ring opening of epoxides and aziridines using cerium(III) chloride

A wide variety of epoxides and aziridines were converted to the corresponding β-halohydrins and β-haloamines using cerium(III) chloride and the cerium(III) chloride/NaI system in acetonitrile. The reactions were highly regioselective and efficient with excellent yields under mild and neutral reaction conditions.