Thiamine hydrochloride (VB1)-catalyzed one-pot synthesis of (E)-N-benzylidene-2-phenyl-1H-benzo[d]imidazo[1,2-a]imidazol-3-amine derivatives

An environmentally benign and efficient method has been developed for the synthesis of (E)-N-benzylidene-2-phenyl-1H-benzo[d]imidazo[1,2-a]imidazol-3-amine derivatives via a four-component reaction of 2-aminobenzimidazole, two molecules of aromatic aldehyde, and trimethylsilanecarbonitrile (TMSCN) in the presence of a catalytic amount of thiamine hydrochloride (VB1) in EtOH at reflux temperature. The advantages of this method are the use of an inexpensive and readily available catalyst, high yields, simple workup, and easy purification.