Ionic liquid-mediated synthesis of coumarin-3-carboxylic acids via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes

摘要

A simple, efficient, and green protocol for synthesis of coumarin-3-carboxylic acids is described via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes in [Hmim]Tfa ionic liquid, which was found to give better results than other ionic liquids. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.