1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-Oxide Hexafluorophosphate (HATU)/Hydroxybenzotriazole (HOBT)-based One-Pot Cyclization of N-Substituted 2-Arylbenzimidazole Derivatives

A simple one-pot synthesis of N-substituted benzimidazoles from aromatic carboxylic acids and aromatic 1,2-diamines in the presence of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate/hydroxybenzotriazole (HATU/HOBT) and N,N-diisopropylethylamine in DMF at 100°C, featuring good to excellent yields and easy workup, is developed. The protocol can be scaled to gram quantities, and no chromatographic purification is required.