Green, Catalyst-Free Protocol for Synthesis of Dihydropyrano[3,2-C]chromenes in Ionic Liquid [bmim]Br as an Efficient Promoting Medium

Abstract

A simple and green procedure for the synthesis of dihydropyrano[3,2-c]chromene derivatives by one-pot three-component reaction of 4-hydroxycoumarin, aromatic aldehydes and malononitrile using [bmim]Br, a neutral ionic liquid, as an efficient medium without any catalysts has been developed. The present methodology offers several advantages, such as simple procedure with an easy work-up, excellent yields, short reaction times, environmentally benign milder reaction conditions.