One-Pot Synthesis of Pyrano[2,3-d]pyrimidinone Derivatives Catalyzed by L-Proline in Aqueous Media

An efficient protocol has been developed for the synthesis of various pyrano[2,3-d]pyrimidinones from condensation of aromatic aldehydes, malononitrile and barbituric-or thiobarbituric acid in aqueous ethanol using L-proline as a neutral bifunctional catalyst.