Domino Cyclization Reaction of o -Diisocyanoarenes for the Synthesis of Imidazo[1,2- a ]pyridinobenzimidazole Backbones.

An efficient procedure to access a variety of connected imidazo[1,2- a ]pyridine and benzimidazole skeletons through the C-N bond was described as a new type of Buchwald-Hartwig reaction. Furthermore, the bis(imidazo[1,2- a ]pyridin-3-yl)aryl-1,2-diamine scaffolds were obtained by changing the equivalent ratio of the starting materials. Some advantages of the protocol are the formation of four new bonds (C═C, C-N), a transition-metal-free reaction, a broad substrate scope, high yields, and mild reaction conditions. The reaction mechanism was confirmed on the basis of DFT calculations.