Synthesis of 5-Aryl-5H-pyrido[2',1':2,3]imidazo[4,5-b]indoles by Domino Pd- and Cu-Catalyzed C–N Coupling Reactions

A series of 5-aryl-5H-pyrido[2',1':2,3]imidazo[4,5-b]indoles was successfully prepared in good yields by a practical four-step strategy. In this procedure, the key step was demonstrated to be the domino Pd-and Cu-catalyzed C–N coupling reactions of 3-bromo-2-(2-bromophenyl)imidazo[1,2-a]pyridine with amines.