Chiral styrene oxides from α-haloacetophenones using NaBH4 and TarB-NO2, a chiral Lewis acid

Abstract High enantioselectivities are obtained for the preparation of chiral styrene oxides through reduction of α-haloacetophenones using TarB-NO 2 reagent and the inexpensive and mild reducing agent NaBH 4 . The epoxides are easily obtained in up to 95% ee through routine acid–base workup of the product alcohols. Either the ( R ) or ( S ) epoxide can be obtained by using the appropriate l - or d -tartaric acid starting material in the TarB-NO 2 reagent.