Nano-CuFe2O4@SO3H Catalyzed Efficient One-Pot Cyclo-Dehydration of Dimedone and Synthesis of Chromeno[4,3-b]chromenes

Chlorosulfonic acid immobilized on CuFe₂O₄ nanoparticles (nano-CuFe₂O₄@SO₃H) was evaluated as a recoverable catalyst for the one-pot cyclo-dehydration of dimedone and synthesis of chromeno4,3-b]chromene derivatives by reaction of arylaldehydes, dimedone or 1,3-cyclohexanedione, with 3-hydroxycoumarine or 4-hydroxycoumarine in good to excellent yield. Also, 2,2′-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was synthesized by the reaction of aromatic aldehyde and dimedone using nano-CuFe₂O₄ in ethanol at room temperature. The catalyst could be recycled several times without significant loss of its catalytic activity. Clean methodologies, easy work-up procedure, high yield and simple preparation of the catalyst are some advantages of this procedure.