Guanidine HCl: a green organo-catalyst for effective multicomponent synthesis of benzodiazepine derivatives under aquatic environment

Abstract

An efficient and environmentally friendly methodology has been developed for the synthesis of 1,5-benzodiazepine derivatives, employing catalytic amounts of guanidine hydrochloride in aqueous conditions. The desired compounds were obtained with high yields by combining variously substituted aryl aldehydes with o-phenylene diamine and dimedone. The protocol offers several advantages, including a rapid reaction time, the use of greener solvents, simple workup procedures, and an uncomplicated purification process, ensuring energy efficiency and versatility. Also, the catalyst can be recycled up to 4-5 cycles without compromising the overall yield, adding to the overall merit of this method. Furthermore, green chemistry metrics such as EcoScale, E-Factor, and Process Mass Intensity (PMI) were employed to evaluate the environmental impact of the process thoroughly.