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

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 MoCl4(CH3CN)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, [Et3NH][Mo{tBuC4}Cl(CH3CN)] have been investigated. The progress of reactions was monitored with reference to an internal standard by means of 1H 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.

Graphical abstractCatalytic epoxidations of styrene, cyclohexene, 1-octene, and 3,3-dimethyl-1-butene have been investigated using MoCl4(CH3CN)2, Mo(CO)3(PTA)3, Mo(CO)3(Mes), and [Et3NH][Mo{tBuC4}Cl(CH3CN)] as precatalysts.Figure optionsDownload full-size imageDownload as PowerPoint slide