Efficient Epoxidation of alkenes with aqueous hydrogen peroxide catalyzed by methyltrioxorhenium and 3-cyanopyridine

The epoxidation of alkenes with 30% aqueous hydrogen peroxide:is catalyzed efficiently by methyltrioxorhenium (MTO) in the presence of pyridine additives. The addition of 1-10 mol % of 3-cyanopyridine increases the system's efficiency for terminal and trans-disubstituted alkenes resulting in high isolated yields of the corresponding epoxides. The system allows for epoxidation of alkenes with Various functional groups. Alkenes leading to acid-sensitive products are efficiently epoxidized using a mixture of pyridine and 3-cyanopyridine as additives. This method is operationally very simple and uses an environmentally benign oxidant.,The effects of different pyridine additives on the alkene conversion and the catalyst lifetime are discussed.