Nano silica-bonded N-propylsulfamic acid as an efficient and environmentally benign catalyst for the synthesis of 1,5-benzodiazepines

A heterogeneous nanosilica-bonded N -propylsulfamic acid catalyst was successfully prepared and characterized by FT-IR, powder XRD, SEM–EDX, TEM, 13 C CP–MAS, and TG analyses. The promoting ability of this nanocomposite was probed through highly efficient synthesis of 1,5-benzodiazepines by a three component reaction of o -phenylenediamines, 3-acetyl-4-hydroxycoumarin, and different aldehydes. The catalyst was recycled for eight cycles with almost unaltered catalytic activity. The advantages of present protocol are energy efficiency, excellent yield of products in shorter reaction time (5–10 min), and use of non-toxic catalyst/solvent. Graphical abstract