Synthesis of a novel poly (ethylene glycol) grafted N,N-dimethylaminopyridine functionalized dicationic ionic liquid and its application in one-pot synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives in water

A novel poly (ethylene glycol) grafted N,N-dimethylaminopyridine functionalized dicationic ionic liquid was prepared and identified. It was used as a recyclable catalyst for the synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives with excellent yields through a one-pot three-component reaction of aromatic aldehydes, malononitrile and 4-hydroxycoumarin in water. This protocol offers several advantages such as mild reaction conditions, wide substrate flexibility, simple operation and environmental friendliness. Furthermore, the catalyst could be reused several times without any obvious loss of catalytic activity.