A novel sulfonic acid functionalized ionic liquid catalyzed multicomponent synthesis of 10,11-dihydrochromeno[4,3-b]chromene-6,8(7H,9H)-dione derivatives in water

Three-component reactions of 4-hydroxycoumarin, aldehydes, and cyclic 1,3-dicarbonyl compounds were prompted by novel sulfonic acid functionalized ionic liquids 1,3-dimethyl-2-oxo-1,3-bis(4-sulfobutyl)imidazolidine-1,3-diium hydrogen sulfate ([DMDBSI]·2HSO4) in water at reflux temperature to provide a novel series of 10,11-dihydrochromeno[4,3-b]chromene-6,8(7H,9H)-dione derivatives for the first time in high yields.