Epoxidation of alkenes catalyzed by some molybdenum(0) and molybdenum(IV) complexes

Abstract Catalytic epoxidations of styrene, cyclohexene, 1-octene, and 3,3-dimethyl-1-butene have been explored utilizing a variety of molybdenum(0) and molybdenum(IV) complexes as precatalysts and tert -butylhydroperoxide (TBHP) as oxidant. The catalytic activities of the complexes MoCl 4 (CH 3 CN) 2 , Mo(CO) 3 (PTA) 3 (PTA = 1,3,5-triaza-7-phosphaadamantane), Mo(CO) 3 (Mes), and a molybdenum(IV) calix[4]arene salt, [Et 3 NH][Mo{ t BuC4}Cl(CH 3 CN)] have been investigated. The progress of reactions was monitored with reference to an internal standard by means of 1 H NMR spectroscopy. Most of the complexes were found to be effective precatalysts with low catalyst loadings, giving rise to good to excellent conversion of alkenes and yield of the epoxides with the formation of minimal amount of corresponding diol and other side products. The catalytic reactions were found to be most efficient between 100 and 110 °C in minimal solvent or without added solvent.