Novel and efficient catalysts for the one-pot synthesis of 3,4-dihydropyrano[ c]chromene derivatives in aqueous media

Abstract

Diammonium hydrogen phosphate, (NH 4) 2HPO 4(DAHP), efficiently catalyzes the one-pot, three-component reaction of an aromatic aldehyde, malononitrile and 4-hydroxycoumarin in aqueous media under mild conditions at room temperature, to afford the corresponding dihydropyrano[ c]chromenes in high yields. ( S)-Proline has also been used as another neutral catalyst for this reaction at reflux.