Asymmetrically epoxidizing reaction

PURPOSE: To provide an optically active modification of a benzopyran compound useful as an intermediate for pyranobenzoxadiazole as a hypotensive agent. CONSTITUTION: The objective optically active modification a benzopyran compound of formula I (R is H or amino-protecting group; the absolute coordination of C denoted with * is R or S), which can be obtained, for example, by reaction of an olefin compound of formula II with an optically active manganese complex of formula III or IV (R 1 to R 5 are each H, 1-4C alkyl, F, etc.; R 6 is 0-4C alkyl; where, when R 6 is ethyl, R 1 and R 2 or R 3 and R 4 are not phenyl at the same time; Ar is F, Cl, 1-4C alkyl, etc.; X - is a counter anion capable of forming a salt) in the presence of an oxidizing agent (e.g. iodobenzene, sodium hypochlorite) in a solvent such as water or dichloromethane (when the oxidizing agent is sodium hypochlorite, a two-phase system such as a combination of water with dichloromethane is preferable) pref. at -20 to 25°C. COPYRIGHT: (C)1993,JPO&Japio