Multi-component reaction between aromatic aldehyde, ethyl acetoacetate and urea catalyzed by Brönsted ionic liquid under microwave irradiation

Abstract

[(SO3H)4C4C1Im]HSO4 is a Brönsted ionic liquid, which was found to be an effective catalyst for organic synthesis. Ionic liquid was prepared from 1-methylimidazole and 1,4-butanesultone (ratio = 1:1), structure of [(SO3H)4C4C1Im]HSO4 was characterized by using nuclear magnetic resonance NMR spectroscopy and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS). Ionic liquid was used as a catalyst for multi-component reaction, which afforded the desired products in high yields (over 80%) and short reaction time (5 min) under microwave irradiation. The catalyst could be recycled several times without loss of efficient catalytic activity.