Efficient, Green, Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction Catalyzed by Cu(NO₃)₂·3H₂O

Abstract

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones derivatives via a three-component Biginelli reaction using copper nitrate as a catalyst under solventless conditions is reported, providing a green, rapid, efficient, and convenient method for the preparation of Biginelli compounds in good yields.

Keywords:

• Biginelli reaction
• copper nitrate
• 3,4-dihydropyrimidin-2(1H)-ones

ACKNOWLEDGMENT

We are grateful for financial support from the National Nature Science Foundation of China (Grants 20772024 and 20802016).

Notes

^a Reaction conditions: benzaldehyde (3 mmol), ethyl acetoacetate (4.5 mmol), urea (6 mmol), and catalyst stirring in solvent (2 mL, entries 12–16) at 70 °C.

^b Isolated yield.

^c Room temperature.

^a Reaction conditions: aldehyde (3 mmol), ethyl acetoacetate or acetylacetone (4.5 mmol), urea or thiourea (6 mmol), and Cu(NO₃)₂·3H₂O (5 mol%) stirring without a solvent at 70 °C.

^b Isolated yield.

^c 90 °C.