A green protocol for synthesis of pyran annulated hetrocyclic systems using Na2SO4 as an efficient catalyst

Na2SO4 as an inexpensive and effective catalyst has provided a green protocol for the synthesis of tetrahydrobenzo[b]pyran, pyrano[2,3-d]pyrimidinone and dihydropyrano[3,2c]chromene derivatives from the three-component domino reaction of aromatic aldehydes and malononitrile with 4-hydroxycoumarin/ dimedone/ barbituric acid in ethanol/water as a mixture of solvent that, this mixture entirely is green solvent. Products could simply be separated from the catalyst. Using neutral and mild conditions, short reaction time, environmentally benign procedure, high to excellent yields of the products and easy work-up without using column chromatography are the advantages of this method. By virtue of these advantages, sodium sulfate can be used as catalyst in the organic transformations.