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

• Application of CTMAB-bentonite for the synthesis of dihydropyrano[c]chromenes.
• Surfactant modified bentonite presented the highest catalytic activity.
• The surfactant modified bentonite was stable in continuous experiments.
• The recovered catalyst was reused for five cycles without loss of its activities.
• A complete catalytic mechanism is proposed.

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.

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