Simple, Highly Efficient Synthesis 2-Amino-4-phenyl-4,5,6,7-tetrahydropyrano[3,2-c]carbazole-3-carbonitrile Derivatives Using Silica Supported Dodeca-Tungstophosphoric Acid DTP/SiO2

The one-pot multicomponent efficient and easily operational protocol has been developed for the synthesis of tetrahydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives. The methods work via the multicomponent reaction between 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one , aldehyde and malononitrile  catalyzed by the silica-supported dodeca tungstophosphoric acid (DTP/SiO2) catalyst. The protocol is practically green, milder reaction condition, higher yield, with short reaction times and recyclability of the catalyst.