Montmorillonite K10: An efficient catalyst for solvent-free synthesis of 1,5-benzodiazepine derivatives

2,3-Dihydro-1H-1,5-benzodiazepines have been synthesized under solvent-free conditions in good yields from o-phenylenediamine and ketones catalyzed by montmorillonite K10. This method has advantages of mild reaction conditions, simple operation, and environmental friendliness.