A Novel Triazole Bonded Silica Heterogeneous Catalyst for the One-Pot Synthesis of Pyrazolopyranopyrimidines and Dihydro-1H-pyrano[2,3-c]pyrazol-6-ones

We described here, the preparation of silica bonded n-propyl-4H-1,2,4-triazol-3-amine chloride by the reaction of 3-chloropropyl silica and 3-amino-1,2,4-triazole as a novel heterogeneous catalyst. The structure of the catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), dispersive X-ray spectroscopy (EDX), and scanning electronic microscopy (SEM). These techniques confirmed the catalyst was successfully synthesized. For evaluation of the catalytic activity and reusability of the catalyst, it was employed for the one-pot synthesis of dihydro-1H-pyrano[2,3-c]pyrazol-6-one and pyrazolopyranopyrimidine scaffolds. These compounds were prepared via the four-component catalytic reaction of hydrazine hydrate, ethyl acetoacetate, aromatic aldehydes, and Meldrum's acid or barbituric acid (dimethylbarbituric acid). After completion of the reaction, the rapid separation and facial recycling of the catalyst were accomplished.

Automated summary

In this study, a novel heterogeneous catalyst, silica bonded n-propyl-4H-1,2,4-triazol-3-amine chloride, was prepared. The structure of the catalyst was confirmed through characterization techniques. The catalyst exhibited excellent catalytic activity and reusability in a one-pot reaction.