[bmim]Br as an Efficient Medium for the Green and Catalyst-Free Synthesis of Biscoumarin Derivatives

Abstract

A series of biscoumarin derivatives were synthesized via the reaction of 4-hydroxycoumarin and aromatic aldehydes in the presence of ionic liquid, 1-butyl-3-methylimidazolium bromide, [bmim]Br, without the use of any catalyst. This method has the advantages of good yields, milder reaction conditions, easier work up, no catalyst and environmentally benign procedure.