An unusual synthesis of ergosterol acetate peroxide

Abstract

Trityl tetrafluoroborate and tris-(p-bromophenyl)aminium cation-radical are exceptionally effective catalysts for oxygenation of ergosteryl acetate (I; R = Ac) to the peroxide (II; R = Ac); the trityl cation catalysed reaction is a photo-oxygenation, whilst the aminium cation-radical catalysed reaction is thermal.