Ionic Liquid–Catalyzed One-Pot Synthesis of 1H-Pyrano[2,3-d]pyrimidin-2(8aH)-one Derivatives via Three-Component Reaction under Solvent-Free Conditions

Abstract

A series of 1H-pyrano[2,3-d]pyrimidin-2(8aH)-one derivatives were synthesized via one-pot, three-component reaction of aromatic aldehydes, urea or thiourea, and 3,4-dihydro-2H-pyran using the green and inexpensive Brønsted acidic ionic liquid 1-methyl-2-pyrrolidinone hydrosulfate ([Hnmp]HSO₄) as catalyst under solvent-free conditions. The method has several advantages such as mild conditions, shorter reaction time, good yields, and environmentally benign procedure. Moreover, the catalyst could be recovered conveniently and reused at least four times without evident loss of activity.

GRAPHICAL ABSTRACT

Keywords:

• Ionic liquid
• 1H-pyrano[2,3-d]pyrimidin-2(8aH)-one derivatives
• solvent-free
• three-component reaction

ACKNOWLEDGMENT

This work was financially supported by the Research Foundation of Zhejiang Provincial Education Department (No. 20060811).

Notes

^a All reactions were run with 4-fluorophenyl aldehyde (1a, 1 mmol), urea (2, 1 mmol), 3,4-dihydro-2H-pyran (3, 1 mmol), and 10 mol % [Hnmp]HSO₄.

^b Isolated yield.

^a All reactions were run with 4-fluorophenyl aldehyde (1a, 1 mmol), urea (2, 1 mmol), 3,4-dihydro-2H-pyran (3, 1 mmol), and 10 mol% [Hnmp]HSO₄ under solvent-free conditions.

^b Isolated yield.

^a Isolated yield.

^a Isolated yield.