Abstract
The time courses of the spectral change, decomposition, and consumption of Fe (acac)3, tert-butyl (τBu) hydroperoxide, and cholesteryl acetate, respectively, in the title reaction were followed and the reaction was inferred to be initiated by the active species originating from the interaction of the ferric chelate and the hydroperoxide. Radical processes seem to participate in this reaction, since it was completely inhibited by a radical scavenger (BHT), which was also effective in blocking the further transformation of the intermediary C (7)-τBu-peroxide. The τBuBr-KO2 system generating τBuOO radicals oxidized cholesteryl methylether almost exclusively to an epoxide. The τBuOOH-KO2 system generating τBuO radicals, on the other hand, abstracted the allylic C (7)-hydrogen to give the τBu-peroxide, the alcohol, and the ketone, but no epoxide. The intermediary τBu-peroxide was assumed to be produced also by the nucleophilic attack of τBuOOH on the allylic cation, to which the initially formed C (7)-radical species was further oxidized. A proposed mechanism is presented for the title reaction.
