Brønsted-Acidic Imidazolium Ionic Liquid [bmim(SO3H)][OTf]: A Mild Catalyst for Highly Efficient Synthesis of Coumarins

Abstract

The use of Brønsted-acidic imidazolium ionic liquid [bmim(SO₃H)][OTf] as a catalyst for the high yielding synthesis of a wide variety of coumarins under mild conditions via Pechmann condensation has been demonstrated. This method is simple and has benefits from the easy way to isolate coumarins in good yields. In comparison with the classical Pechmann condensation, this new method consistently has the advantage of high yields and good purity.