Copper‐amine complex immobilized on nano NaY zeolite as a recyclable nanocatalyst for the environmentally friendly synthesis of 2‐amino‐4H‐chromenes

Abstract

The nano NaY zeolite‐supported copper‐amine complex was prepared by postmodification of the nano NaY zeolite with 3‐chloropropyl trimethoxysilane (CPTMS) and [2‐({3‐[(2‐aminoethyl)thio]propyl}thio)ethyl]amine followed by coordination with Cu (I) ion. Various techniques such as Fourier transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron micrograph (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), t‐plot, energy dispersive spectroscopy (EDS), inductively coupled plasma (ICP), and elemental analyses were used to characterize the structure of the synthesized catalyst. The catalytic activity of the synthesized nano‐sample was evaluated in a three‐component synthesis of 2‐amino‐4H‐chromene derivatives, which resulted in high reaction yields and short reaction times under green conditions. The catalyst is separated by filtration and can be reused for at least seven consecutive runs without significant loss of catalytic activity. The nature of the supported [2‐({3‐[(2‐aminoethyl)thio]propyl}thio)ethyl]amine (NN) on the zeolite's surface improved the catalytic activity of the zeolite, provided homogeneity to the catalyst, and enhanced the capability of coordination with copper ions. Facile catalyst recovery and reuse, simple setup procedure and generality of the method, high turnover number (TON), and aqueous ethanol as a green solvent make this procedure an environmentally benign approach for preparing the titled heterocycles. The findings in this work revealed that the introduced catalytic system could be used to prepare other beneficial heterocyclic compounds under environmentally benign conditions.