Further Studies on the Pyrolytic Domino Cyclization of Stabilized Phosphonium Ylides Bearing an Ortho-Aminophenyl Group

Four new, stabilized phosphonium ylides containing a 2-(benzyl(methyl)amino)phenyl group have been prepared and characterized and are found, upon pyrolysis under gas-phase flow conditions, to lose Ph₃PO and benzyl radicals to afford new heterocyclic products resulting from domino cyclization of both C- and N-centered radicals. Most products arise from processes of the former type and have quinoline, phenanthridine, or ring-fused phenanthridine structures, while in one case, a process of the latter type leads to a benzocarbazole product. The X-ray structure of a 2-(methyl(tosyl)amino)phenyl ylide is also reported.