Asymmetric Epoxidation with Optically Active (Salen)manganese(III) Complexes: From Which Direction Does the Olefin Approach the Metal-Oxo Bond?

Abstract
Asymmetric epoxidation of trans-stilbene, cis-ß-methylstyrene, dihydronaphthalene, and 6-acetamido-2,2-dimethyl-7-nitrochromene was examined with various optically active (salen)manganese(III) complexes as catalysts. From the results, it was strongly suggested that cis-olefin approaches metal-oxo bond along nitrogen-metal bond axis.