# CS-[BiC-PiC]-NiCl4: a green and effective heterogeneous catalyst for one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives

## TL;DR

A new green catalyst was developed for efficiently making 2,3-dihydroquinazolin-4(1H)-one compounds, which are important in pharmaceuticals.

## Contribution

A novel nickel-containing dicationic ionic liquid immobilized on chitosan was developed as a heterogeneous catalyst for sustainable synthesis.

## Key findings

- The catalyst achieved high yields (93–97%) in short reaction times (3–8 minutes) for synthesizing 2,3-dihydroquinazolin-4(1H)-one derivatives.
- The catalyst demonstrated excellent recyclability over five runs with no detectable nickel leaching.
- The method is solvent-free, operationally simple, and allows for easy recovery of the catalyst.

## Abstract

In this study, a novel nickel ion-containing dicationic ionic liquid immobilized on chitosan (CS-[BiC-PiC]-NiCl4) was designed, synthesized, and fully characterized by using various techniques such as Fourier transform infrared spectroscopy (FT-IR), 1H NMR and 13CNMR spectra, X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and inductively coupled plasma (ICP) analysis. The theoretical electronic structure, catalytic mechanism, and identity of most of the active sites in the CS-[BiC-PiC]-NiCl4 system were investigated using a suite of computational methods, including density functional theory (DFT), molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules (QTAIM), and reduced density gradient (RDG) analysis. Its potential was demonstrated in the facile and eco-friendly synthesis of pharmacologically important 2,3-dihydroquinazolin-4(1H)-one derivatives using two distinct protocols, including the reaction of 2-aminobenzamide with aldehydes and the reaction of isatoic anhydride with ammonium acetate and aldehydes under neat conditions at 120 °C, demonstrating excellent recyclability over five runs, achieving high yields (93–97%) with short reaction times (3–8 minutes). This offers a sustainable and practical synthetic platform, facilitated by the synergistic interplay between the nickel Lewis acid sites and the chitosan support. This process provides significant advantages, including operational simplicity, solvent-free conditions, straightforward product isolation, and easy recovery of a cost-effective catalyst, which demonstrated exceptional stability over multiple cycles with no detectable nickel leaching, underscoring its truly heterogeneous nature. Consequently, this methodology represents a sustainable and practical approach for the synthesis of these valuable heterocycles.

In this study, CS-[BiC-PiC]-NiCl4 was designed, synthesized, and fully characterized by using various techniques. In continue this reagent was used for the promotion of the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives.