One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Derivatives with H₂SO₄ Supported on Silica Gel or Alumina

Abstract

The one-pot condensation of aromatic aldehydes, β-dicarbonyl compounds, and urea or thiourea in the presence of H₂SO₄ supported on silica gel or alumina (80% m/m) in refluxing n-hexane produces 3,4-dihydropyrimidin-2(1H)-ones and their sulfur derivatives in high to excellent yields.

Keywords:

• Alumina
• Biginelli reaction
• 3,4-dihydropyrimidin-2(1H)-one
• H₂SO₄
• silica gel

The authors gratefully appreciate the financial support of this work by the research council of Urmia University.

Notes

^a All reactions were carried out with 1 mmol of benzaldehyde in 5 mL of solvent under reflux conditions.

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

^b Yields refer to isolated pure products.

^a The reactions with H₂SO₄/SiO₂ or Al₂O₃ and silica sulfuric acid were carried out in refluxing n-hexane and ethanol, respectively.