Mesoporous Ionic Liquid‐Functionalized Triazine‐Based Covalent Organic Polymer: A Heterogeneous Catalyst for the Synthesis of Pyranopyrazoles and Pyranocoumarins Under Sustainable Conditions

This sustainable protocol enables one-pot synthesis of pyranopyrazole and pyranocoumarin derivatives in excellent yields (88%-95%) within 15-22 minutes, using MFP@IL, a micro-mesoporous ionic liquid-functionalized triazine-based covalent organic polymer with bifunctional acid-base sites. The method features mild aqueous conditions, broad substrate scope, simple product isolation, and remarkable catalyst recyclability upto eight cycles, underscoring its efficiency and green potential.

Abstract

Herein, we report the synthesis of a recyclable, mesoporous heterogeneous catalyst (MFP@IL) by functionalizing an ammonium-cation-based ionic liquid onto a melamine-paraformaldehyde covalent organic polymer. The catalytic performance of MFP@IL was evaluated by synthesizing a library of pyranopyrazoles and pyranocoumarins via a one-pot, multicomponent reaction under sustainable reaction conditions. The reactions were performed at room temperature (RT) in an aqueous medium. MFP@IL displayed excellent catalytic efficacy, high thermochemical stability, and high reusability for up to eight catalytic cycles. MFP@IL was extensively characterized by various spectroscopic techniques, such as Energy Dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), and Thermal Gravimetric (TG) analyses. The high efficiency of the protocol was demonstrated by its broad compatibility with various aldehydes and the ability to achieve excellent yields (88%–95%) within a short reaction time (15–22 min). A simple workup procedure, high purity of the title compounds, easy catalyst recovery, and use of water as a green solvent are other notable features of this methodology.

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