Cellulose Sulfuric Acid as an Eco-Friendly Catalyst for Novel Synthesis of Pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones

A novel synthesis of a series of pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones has been developed from reactions of 1-(5-methyl-1-phenyl-1H-pyrazol-4-yl)-3-arylprop-2-en-1-ones and 7-amino-1,3-disubstituted[1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-ones in dioxane under thermal conditions, using cellulose sulfuric acid as an eco-friendly acid catalyst. The reaction mechanism was proposed and the structures of the newly synthesized compounds were established on the basis of spectral data (mass spectrometry, infrared, H-1 and C-13 nuclear magnetic resonance) and elemental analyses.