Sustainable and selective synthesis of benzimidazole scaffolds using deep eutectic solvents

Abstract

In the present article, the catalytic activity of Zr based DESs (DES 1-DES 3) and Ce based DESs (DES 4-DES 7) was compared for the synthesis of benzimidazole derivatives. Among the seven DESs, excellent conversion was observed for DES 1 (formed from ZrOCl2·8H2O and urea at 1:5 ratio). This might be due to the higher acidity and lower viscosity of DES 1 compared to others. The present method was found to be efficient for the synthesis of 2-substituted benzimidazoles with interesting characteristics such as easy preparation of the catalyst, high product yield, simple reaction procedure and the reusability of the catalyst. It is for the first time, a recyclable and selective protocol for the synthesis of benzimidazoles using deep eutectic solvent was reported.

Keywords

• Deep eutectic solvents
• Recyclable catalyst
• Benzimidazole synthesis
• Substituent effect