SYNTHESIS OF PHENANTHRIDINES BY RADICAL C-ARYL-C-ARYL COUPLING

Treatment of N-(o-bromobenzyl)anilines with 1-3 equivalent amounts of n-tributyltinhydride, in the presence of 0.5 to 0.6 mol equiv. of AIBN , results in the formation of phenanthridines in good yields. The mech anism of the oxidation step is probed with a deuterated aniline deriva tive and azobiscyclohexylcarbanonitrile (ABCN) as the initiator. It is shown that the carbon centred radical derived from the latter does no t act as the hydrogen abstracting species. Copyright (C) 1996 Elsevier Science Ltd