Gadolinium oxide loaded zirconia and multi-component synthesis of novel dihydro-pyrazolo[3,4-d]pyridines under green conditions

Abstract

New gadolinium oxide loaded zirconia (Gd2O3/ZrO2) was synthesised, and its structural properties were fully established by powder XRD, SEM, BET, TEM and FT-IR analyses. We report the superior catalytic activity of Gd2O3/ZrO2 in the synthesis of fourteen novel dihydropyrazolo[3,4-b]pyridine scaffolds in excellent yields (90–96%) in a swift reaction (25–30 min). The three-component condensation reaction at room temperature with ethanol as the medium involved 3-amino-1H-pyrazole, benzyl acetoacetate and chosen benzaldehyde as precursors. The heterogeneous catalyst performed with similar catalytic efficacy up to five runs without significant loss of its activity. Simple workup, speedy reaction, mild reaction conditions, superb yields, reusability, avoidance hazardous reagents and no need for chromatography purification are the advantages of the protocol.