Copper-catalyzed one-pot synthesis of benzimidazole derivatives

A simple, efficient, and environmentally benign method has been developed for the synthesis of 2-substituted benzimidazoles through a one-pot reaction of phenylenediamines with aryl aldehydes in excellent isolated yields under mild conditions using Cu(II) complex as the selective, recyclable, and heterogeneous catalyst at ambient temperature. The Cu(II) complex as a heterogeneous catalyst can be reused in further catalytic reactions, and it was found that its activity remained largely unchanged for eight successive runs. No metal-complex leaching was observed after the consecutive catalytic reactions. The salient features of this method include mild conditions, high yields, simple procedure, and good recovery and reusability of the heterogeneous catalyst.