Facile and Selective Synthesis of Imidazobenzimidazoles via a Copper-Catalysed Domino Addition/Cycloisomerisation/Coupling Process

A copper(I)-catalysed domino transformation for the synthesis of tricyclic imidazobenzimidazole derivatives was developed. Using readily available primary propargylic amines and o-haloarylcarbodiimides as the starting materials, a variety of substituted benzo[d]imidazo[1,2-a]imidazoles was efficiently and selectively assembled. Further investigations indicated that the domino reaction was likely the result of a novel addition/cycloisomerisation/coupling process.