Microwave assisted one pot three component synthesis of propargylamine, tetra substituted propargylamine and pyrrolo[1,2-a]quinolines using CuNPs@ZnO–PTh as a heterogeneous catalyst

Abstract

The present work deals with the investigation and catalytic activity analysis of copper nanoparticles (CuNPs) supported on a zinc oxide–polythiophene (ZnO–PTh) nanocomposite. CuNPs@ZnO–PTh was prepared using a simple impregnation method and characterized using various techniques (XRD, XPS, FT-IR, SEM, ICP-AES, TEM, TEM-EDS and EDAX). HR-TEM indicates that CuNPs supported on ZnO–PTh were of spherical shape and distributed uniformly over the nanocomposite with a particle size of ∼2–8 nm. Further, the synthesized CuNPs@ZnO–PTh was used as a heterogeneous catalyst for the synthesis of propargylamine, tetra substituted propargylamine (A³ and KA² coupling reactions) and pyrrolo[1,2-a]quinoline (A³ coupling reactions) using a microwave technique in ethylene glycol as a recyclable, green and biodegradable solvent with 98% yield. The high catalytic activity of CuNPs@ZnO–PTh was due to the high surface area and synergetic effect of both the CuNPs and ZnO–PTh nanocomposite, which makes it cost effective and environmentally benign with high atom economy. Considering all above facts, this protocol was found to be more efficient and sustainable as compared to the available commercial methods.