Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones

Abstract

Amethod is presented for the direct transformation of ak etone to the corresponding reduced alkylc hloride or bromide.T he process involves the reaction of ak etone trityl hydrazone with tBuOCl to give ad iazene which readily collapses to the a-chlorocarbinyl radical, reduction of whichby ah ydrogen atom source gives the alkylc hloride product. The use of N-bromosuccinimide provides the corresponding alkyl bromide.T his unique transformation provides ar eductive halogenation that complements Bartons redox-neutral vinyl halide synthesis.