No abstract

A concise and efficient approach to synthesizing coumarin-fused pyrazolo[3,4-b]pyridine via silica sulfuric acid (SSA) catalyzed three-component domino reaction under microwave irradiation has been demonstrated. Participation of various alcohols in construction of coumarin derivatives has been described for the first time. Short reaction time, high yields, one-pot procedure, usage of eco-friendly catalyst, and solvent are the key features of this method.

Coumarin and pyrazolo[3,4-b]pyridine are structurally essential elements in biologically active natural compounds and are extremely important in medicinal chemistry by serving as key pharmacophores in drug discovery. In this article, the efficient synthesis of coumarin-fused pyrazolo[3,4-b]pyridine via three-component domino reaction of aldehydes, coumarin derivative and 5-aminopyrazole in one step catalyzed by niobic acid modified with phosphoric acid under microwave irradiation has been achieved. The one-pot procedure, eco-friendly catalyst and solvent as well as simple operation are the key features of this method. The structures of the products were identified by IR, NMR, and HRMS spectra.