Borax: An Ecofriendly and Efficient Catalyst for One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones under Solvent-Free Conditions

Abstract

Borax in the presence of a very small amount of 5 M sulfuric acid efficiently catalyses the three-component condensation of an aldehyde, β-ketoester, and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or 3,4-dihydropyrimidin-2(1H)-thiones in good to excellent yields under solvent-free conditions at 80 °C. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yield, short reaction time (1–2 h), easy workup, and no use of volatile organic solvent.

Keywords:

• Biginelli reaction
• borax
• 3,4-dihydropyrimidin-2(1H)-ones
• solvent free

ACKNOWLEDGMENTS

J. N. thanks head, Centre for the Environment Indian Institute of Technology Guwahati, for his encouragement and support to publish this work. Thanks are also due to the Department of Chemistry and CIF, Indian Institute of Technology Guwahati, for providing instrument facilities.

Notes

^a Reaction conditions: benzaldehyde 1 mmol; ethyl acetoacetate 1 mmol; 80 °C.

^b Isolated yield.