Silica-Supported Ionic Liquid Si-[SbSipim][PF₆]: An Efficient Catalyst for the Synthesis of 3,4-Dihydropyrimidine-2-(1H)-ones

Abstract

Silica-supported sulfonic acid–functional ionic liquid (Si-[SbSipim][PF₆]) was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones via a one-pot, three-component Biginelli reaction. The catalyst could be easily separated and reused six times without noticeable reduction inactivity. The process was simple and proceeded in excellent yields.

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GRAPHICAL ABSTRACT

Keywords:

• Biginelli reaction
• reused
• support ionic liquids

ACKNOWLEDGMENT

We are grateful to the Science and Technology Foundation of Shanghai Institute of Technology (No. KJ 2010-08) for financial support.

Notes

^a 5 mmol benzaldehyde, 5 mmol ethyl acetoacetate, 7.5 mmol urea, reflux 3.5 h in ethanol.

^a 5 mmol benzaldehyde, 5 mmol ethyl acetoacetate, 7.5 mmol urea, 0.4 g Si-[SbSipim][PF₆], reflux.

^b Isolated yield.

^a 5 mmol benzaldehyde, 5 mmol ethyl acetoacetate, 7.5 mmol urea, 0.4 g Si-[SbSipim][PF₆].

^b Reflux 3.5 h in ethanol.

^c Reflux 4.5 h in ethanol.

^d Reflux 5 h in ethanol.