Surfactant modified bentonite (CTMAB-bentonite) as a solid heterogeneous catalyst for the rapid synthesis of 3,4-dihydropyrano[c]chromene derivatives

CTMAB-bentonite was found to be an efficient catalyst for the synthesis of 3,4-dihydropyrano[c]chromene derivatives by one-pot reaction of 4-hydroxycoumarin, aromatic aldehydes, and malononitrile in aqueous ethanol under mild condition. High yields, short reaction time, easy work-up, eco-friendly, non-toxic and reusable catalyst are the advantages of this procedure.