Pyridinium-Based Brønsted Acidic Ionic Liquid as a Highly Efficient Catalyst for One-Pot Synthesis of Dihydropyrimidinones

Abstract

In this work, the synthesis and characterization of 3-carboxypyridinium hydrogensulfate ([Hcpy]HSO₄) as a new Brønsted acidic ionic liquid are reported. This reusable, inexpensive, and green catalyst was employed for one-pot condensation of 1,3-dicarbonyl compounds, aromatic aldehydes and urea or thiourea for the synthesis of the corresponding 3,4-Dihydropyrimidin-2(1H)-ones. The reactions were carried out under solvent-free and green conditions. The procedure gave the products in excellent yields within very short reaction times.

GRAPHICAL ABSTRACT

Keywords:

• Biginelli reaction
• Brønsted acidic ionic liquid
• 3-carboxypyridinium hydrogensulfate
• dihydropyrimidinone
• one-pot
• solvent-free

ACKNOWLEDGMENTS

We gratefully acknowledge the funding support received for this project from the Isfahan University of Technology (IUT), Iran (A. R. H.). Further financial support from the Center of Sensor and Green Chemistry Research (IUT) is gratefully acknowledged.

Notes

^a 3-Nitrobenzaldehyde (1 mmol), urea (1.5 mmol), ethylacetoacetate, and IL as catalyst.

^b Isolated yields after purification.

^a Isolated yields after purification.