Synthesis of phenol esters by direct C–H activation of aldehydes using a highly efficient and reusable copper-immobilized polyimide covalent organic framework (Cu@PI-COF)

Abstract

In the present study, we report the design and fabrication of a thermally and chemically stable copper-based polyimide covalent organic framework (Cu@PI-COF) via a facile and straightforward synthetic approach. The as-synthesized Cu@PI-COF proves its supremacy in the synthesis of biologically significant phenol esters by the reaction of 2-hydroxyacetophenone with a series of aldehydes. The obtained catalyst was thoroughly investigated by various physico-chemical techniques, such as FT-IR, XRD, SEM, TEM, AAS, TGA, EDX, ¹³C NMR, BET and ED-XRF. The superior prowess of Cu@PI-COF was demonstrated in the synthesis of phenol esters with good to excellent yields, a wider substrate scope and shorter reaction times under ambient reaction conditions. Besides showcasing remarkable catalytic activity, the catalyst also exhibited excellent recoverability and recyclability in up to seven consecutive runs with no reduction in its catalytic performance, which offers the potential for scale-up in various pharmaceutical applications.