Solvent free synthesis of 1,5-benzodiazepine derivatives over the heterogeneous silver salt of silicotungstic acid under ambient conditions

Abstract

1,5-Benzodiazepine derivatives were synthesized using prepared silver substituted silicotungstic acid (AgSTA) salt as a heterogeneous catalyst under solvent free conditions at room temperature. The solid AgSTA catalyst was synthesized and characterized by X-ray diffraction, FTIR spectroscopy, Raman spectroscopy, FTIR pyridine adsorption, SEM imaging, EDX mapping, and antimicrobial activity was also tested. The AgSTA catalyst showed tremendous catalytic activity in the synthesis of 1,5-benzodiazepine derivatives under solvent free conditions. As a result, 100% conversion of reactants and up to 88.0% yield of 1,5-benzodiazepine in 40 min reaction time were achieved using 10 wt% of AgSTA catalyst. The solid AgSTA catalyst was separated from the reaction mixture by a simple filtration process at the end of the reaction and reused for five cycles without significant loss of catalytic activity and selectivity. The present environmentally benign, solvent free catalytic system is found to be a very convenient, fast, high yielding, and clean method for the synthesis of 1,5-benzodiazepine derivatives.