Opticallyactive N,N′-ethylenebis(α-alkoxycarbonyl-β-ketoimine) was found to be a new class of effective ligand of manganese(III) complexcatalyst for the asymmetric aerobicepoxidation of simple olefins, such as 1,2-dihydronaphthalene derivatives, to afford the corresponding opticallyactive epoxides with good to high enantioselectivities.