Synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole- 3-carboxylates using nano-ZnZr4(PO4)6 as an efficient catalyst

Nanocrystalline ZnZr4(PO4)6 ceramics as an efficient catalyst have been used for the preparation of methyl 6-amino-5-cyano-4- aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates by the four-component reaction of dimethylacetylenedicarboxylate, hydrazinehydrate, malononitrile and aromatic aldehydes in water at room temperature. In this research, Nano-ZnZr4(PO4)6 coordinates with the active groups (particular C=O, C≡N and active H), thus increasing the activity of the groups. Also, this nanoscale heterogeneous catalysts present higher surface areas, which are mainly responsible for their catalytic activity. These surface atoms behave as the centers where the chemical reactions could be catalytically activated. The key advantages of this process are high yields, shorter reaction times, reusability of the catalyst, easy work-up, milder reaction conditions and being environmentally benign.