NEW SYNTHESES OF THE AMARYLLIDACAEA ALKALOIDS VASCONINE, ASSOANINE, OXOASSOANINE, PRATOSINE AND ISMINE BY RADICAL CYCLIZATION

methoxybenzyl)-N-(2'-beta-hydroxyethylphenyl)amine when subjected to t he action of AIBN and tri-n-butyltin hydride (TBTH) in benzene, under reflux, yielded the corresponding beta-4-phenanthridinylethyl alcohol. While reduction of the tetracyclic quaternary salt obtained by treatm ent of this alcohol with PBr3 gave assoanine, its oxidation with alkal ine ferricyanide led to a separable mixture of pratosine and oxoassoan ine. The sigma radical, similarly generated from romo-4,5-methylenedio xybenzyl-2'-aminophenylether, afforded the biphenyl alcohol, N-norismi ne. Copyright (C) 1996 Elsevier Science Ltd