MECHANISTIC STUDIES OF THE FREE-RADICAL FRAGMENTATION OF MONOALKYL DIAZENES

Mechanistic studies of the deoxygenation of primary alcohols by Mitsno bu displacement with o-nitrobenzenesulfonylhydrazine (NBSH) reveal tha t the monoalkyl diazene intermediates formed in this process are excee dingly good hydrogen-atom donors toward alkyl radicals, exceeding tri- n-butyltin hydride in reactivity. Competition experiments are describe d wherein the radical intermediates are trapped by intra-and intermole cular addition to carbon-carbon double bonds, to dioxygen, and to the free radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO). (C) 1997 El sevier Science Ltd.