One-Pot Palladium-Catalyzed Synthesis of Selectively Substituted Phenanthridines by Sequential Aryl-Aryl and Heck Couplings, Aza-Michael and Retro-Mannich Reactions

A catalytic synthesis of selectively substituted phenanthridines is achieved through a reaction sequence involving palladium/norbornene-catalyzed unsymmetrical aryl-aryl and Heck couplings followed by aza-Michael and retro-Mannich reactions. In spite of the many steps involved the method is very simple and allows the formation of selectively substituted phenanthridines under mild conditions in a straightforward one-pot reaction starting from readily available aryl iodides and bromides.