Regioselective Synthesis of Dihydrophenanthridines, Benzazepinones and Benzoazocinones

Significance

Efficient Pd-catalyzed regioselective synthesis of dihydrophenathridine or benz­azepinone and benzazocinone derivatives from 2-iodophenylamides, whose regioselectivity depends on choice of conditions, is reported. These intramolecular Heck reactions require the use of phosphine ligands of which PPh₃ gave the highest yields of benzazepinone and benzazocinone products. On the other hand, in the absence of phosphine ligands (Jeffery conditions: T. Jeffery Tetrahedron 1996, 52, 10113-10130), a biaryl coupling reaction is observed to give the dihydrophenanthridine. For substrates with n = 1, the reaction affords quinolinone products in 87% yield.