Epoxidation of olefins catalyzed by molybdenum–siloxane compounds

The triphenylsiloxy complex MoO2(OSiPh3)2 and a related polyhedral metallasiloxane formulated as [MoO2(O2SiPh2)]n have been tested as catalysts for the liquid phase epoxidation of cyclic olefins by tert-butylhydroperoxide at 55 °C. The initial activities increased in the order 1-octene < trans-2-octene < cyclododecene < cyclooctene and the corresponding epoxides were the only observed products. The best results were obtained without the addition of any co-solvents (other than decane), forming solid–liquid systems. Cyclooctene oxide was obtained in quantitative yield within 7.5 h of reaction, and the solid catalysts could be recycled without measurable loss of activity.