Oxygen transfer reactions from an oxaziridinium tetrafluoroborate salt to olefins

Oxaziridinium 5 efficiently epoxidises olefins. It reacts as an electrophilic reagent and does not transfer its oxygen to deactivated double-bonds or carbonyl functions. Epoxidation of cyclic allylic acetates shows a remarkable diastereoselectivity leading to the syn isomer. We propose that the epoxidation reaction proceeds through a one-step process. (C) 1997 Elsevier Science Ltd.