Bismuth(III)-catalyzed rapid and highly efficient synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles in water

2-Aryl-1-arylmethyl-1H-benzimidazoles are prepared in high yields under extremely mild conditions via the condensation of aryl-1,2-diamines with aromatic aldehydes using 10 mol% of bismuth triflate in water. The use of water and readily available bismuth triflate makes this process quite simple, more convenient, and environment-friendly.