Bioinspired AgNPs: Effective and Recyclable Catalysts towards the One‐Pot Synthesis of Hexahydroquinoline Derivatives via Three‐Component Coupling Reaction

Abstract

AbstractGreen synthesis of silver nanoparticles (AgNPs) was carried out using aqueous bark extract of Shorea robusta(Sal tree) as the reducing and capping agent. AgNPs were characterized using modern characterization tools like UV‐Vis, PXRD, FT‐IR, SEM, and HR‐TEM. The catalytic application of the prepared AgNPs in three‐component coupling reaction of aldehyde, malononitrile, and cyclic enamino ketone resulted in good to excellent yields of hexahydroquinoline derivatives. Moreover, the catalyst can be recycled up to 5 times without compromising too much yield. The mechanistic pathway was investigated employing GC‐Mass spectroscopy and supported through the Density Functional Theory (DFT) calculations. A two‐step mechanism has been proposed for the coupling reaction, and the presence of electron‐withdrawing group in the aldehyde component is found to be more favorable than electron‐releasing one in terms of yield with lesser time.