Microwave-assisted green synthesis of 1,5 benzodiazepines using Cu(II)-clay nanocatalyst

Herein, we present a practical, more efficient, environmentally friendly method for the synthesis of 1,5-benzodiazepine via condensation of benzene-1,2-diamine with commercially available ketones. The reaction was performed using various heterogeneous clay based catalysts, including Montmorillonite-K10, Montmorillonite-KSF, Kaoline, and bentonite, and also other clay supported transition metals based catalysts such as, Cu(II)-clay, Pd/Montmorillonite-KSF, Ni/Montmorillonite-KSF, Co/Montmorillonite-KSF, Sn/KSF, and Zn/Montmorillonite-KSF. Among various metal-clay based catalysts tested, Copper (II) adsorbed on clay nanocatalyst was found to be very efficient and showed promising activity for the formation of nitrogen containing heterocycle compound i.e. 1,5-benzodiazepine with excellent yields. An assortment of structurally diverse 1,5-benzodiazepine was prepared in good to excellent yields from easily available starting materials by using this protocol. The catalyst was found to be applicable to aromatic, heteroaryl and aliphatic ketone such as cyclic ketones as well as acyclic ketones. Keywords: Cu-clay, Nanocatalyst, Benzodiazepine, Microwave, Recyclable