NaHSO₄·H₂O as a Heterogeneous Acidic Reagent for Mild and Convenient Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Derivatives

Abstract

One-pot cyclocondensation reaction of aromatic aldehydes, 1,3-dicarbonyl compounds and urea/thiourea in the presence of NaHSO₄·H₂O produced 4-aryl substituted 3,4-dihydropyrimidin-2(1H)-ones and their sulfur analogs in high to excellent yields. The reactions were carried out in refluxing n-hexane and were completed within 2.5–11 h.

Keywords:

• Biginelli synthesis
• 3,4-dihydropyrimidin-2(1H)-one
• heterogeneous
• NaHSO₄·H₂O

The authors gratefully acknowledge the financial support of this work by the Research Council of Urmia University.

Notes

^a Benzaldehyde, ethyl acetoacetate and urea were used in a molar ratio of 1:1:1.2, respectively.

^b The reactions were carried out under reflux conditions.

^a All reactions were carried out with a molar ratio of aldehyde/β-dicarbonyl/urea (thiourea)/NaHSO₄ (1:1:1.2:2.8) in refluxing n-hexane.

^b Yields refer to isolated pure products.

^b The reactions were carried out in CH₃CN under reflux conditions;

^c The reactions were carried out in oil bath at 80°C under solvent-free conditions.