An environmentally friendly synthesis of 1,4-dihydropyrano [2,3-c]pyrazole derivatives catalyzed by tungstate sulfuric acid

An efficient three-component synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazoles via a reaction between 3-methyl-1-phenyl-2-pyrazolin-5-one, aromatic aldehydes and malononitrile using tungstate sulfuric acid as a catalyst was described. Mild conditions, good to excellent yields, easily available catalyst and easy work-up are the key features of this method. (C) 2014 Bahador Karami. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.