A Green and Efficient Method for the Synthesis of 3,4- Dihydropyrano[c]chromene using Phosphate Fertilizers (MAP, DAP and TSP) as Heterogeneous Catalysts

Abstract

This article presents a simple and green method for the synthesis of 3,4-dihydropyrano[c]chromenes, they have been obtained by the condensation of an aromaticaldehyde, malononitrile and 4-hydroxycoumarin in presence of phosphate fertilizers(Monoammonium phosphate MAP, Diammonium phosphate DAP and Triple superphosphateTSP) as heterogeneous catalysts and ethanol as an ecological solvent. This method hasremarkable advantages, such as excellent catalytic performance of the catalysts used inthe ethanol and the facility of preparation of the desired products with high to excellentyields (>92%) in short reaction times varying from 30 to 45 min, the long-term durabilityand easy recovery of catalysts, constitute a good heterogeneous system. All theseadvantages added to the low cost of these catalysts and their ecological profile haveallowed them to be an alternative to the other synthetic and toxic catalysts used previously.