Room temperature synthesis of 1,5-benzodiazepine and its derivatives using cage type mesoporous aluminosilicate catalysts

Here we demonstrate for the first time the synthesis of 1,5-benzodiazepine using AlKIT-5 catalyst through a condensation reaction between o-phenylenediamine (OPDA) and ketones using acetonitrile as solvent at room temperature. The catalyst was found to be highly active and selective, affording a high yield of benzodiazepines. The effect of the aluminium content of the catalyst and the catalyst concentration on the above process was investigated. The catalyst was also successfully employed for the preparation of various derivatives of 1,5-benzodiazepine using substituted OPDAs and various ketones. In all cases, the reactions are highly selective and are completed within 1–2.5 h. The catalyst showed excellent activity in all the cases, showing 85–97% isolated yield of the corresponding derivatives of 1,5-benzodiazepine. The high activity of the catalyst is mainly due to its high acidity, excellent textural parameters such as high surface area, large pore volume, and cage type 3D porous structure.