Highly enantioselective cyclopropanation of styrene derivatives using Co(III)-salen complex as a catalyst

Article abstract of DOI:10.1016/S0040-4020(97)00423-7

Optically active (salen)cobalt(III) bromide complex 6-Br was found to be an efficient catalyst for asymmetric cyclopropanation of styrene derivatives. For example, the reaction of 4-chlorostyrene and tert-butyl diazoacetate in the presence of 6-Br proceeded with high enantioselectivity of 96% ee as well as high trans-cis selectivity (97:3) to give tert-butyl 2-(4-chlorophenyl)cyclopropane-1-carboxylate as a major product.