Domino Knoevenagel condensation, Michael addition, and cyclization using ionic liquid, 2-hydroxyethylammonium formate, as a recoverable catalyst

The Knoevenagel condensation reaction of aromatic aldehydes with malononitrile or dimedone was investigated. Also, the three-component and one-pot synthesis of 2-amino-5-oxo-4-aryl-4,5-dihydropyrano [3,2-c]chromene-3-carbonitrile derivatives by condensing 4-hydroxycoumarin, aldehydes and malononitriles using a catalytic amount of 2-hydroxyethylammonium formate as an effective ionic liquid without using any additional co-catalyst under solvent-free conditions at room temperature is reported. Furthermore, the domino Knoevenagel condensation, conjugate addition, and cyclization for the preparation of tetrahydrobenzo[b]pyran, and spirooxindole derivatives in high atomic efficiency take place in excellent yields. (C) 2010 Elsevier B.V. All rights reserved.