Application of Deep Eutectic Solvents in the Synthesis of Substituted 2-Mercaptoquinazolin-4(3H)-Ones: A Comparison of Selected Green Chemistry Methods

Abstract

In this study, deep eutectic solvents (DESs) were used as green and eco-friendly media for the synthesis of substituted 2-mercaptoquinazolin-4(3H)-ones from different anthranilic acids and aliphatic or aromatic isothiocyanates. A model reaction on anthranilic acid and phenyl isothiocyanate was performed in 20 choline chloride-based DESs at 80 °C to find the best solvent. Based on the product yield, choline chloride:urea (1:2) DES was found to be the most effective, while DESs acted both as solvents and catalysts. Desired compounds were prepared with moderate to good yields using stirring, microwave-assisted, and ultrasound-assisted synthesis. Significantly, higher yields were obtained with mixing and ultrasonication (16–76%), while microwave-induced synthesis showed lower effectiveness (13–49%). The specific contribution of this research is the use of DESs in combination with the above-mentioned green techniques for the synthesis of a wide range of derivatives. The structures of the synthesized compounds were confirmed by 1H and 13C NMR spectroscopy.

Green synthesis of 2‐thioxo‐4‐quinazolinones from 2‐aminobenzamide and isothiocyanates

“…38 Mario et al used choline chloride-based deep eutectic solvents (DES) to synthesize 2-thioxo-4-quinazolinones from various anthranilic acids and aliphatic or aromatic isothiocyanates. 39 Here, we report novel organic solvent-free and additive-free green synthetic methods of straightforward access to 2-thioxo-4-quinazolinones from 2-aminobenzamide and isothiocyanates.…”