l-Proline-catalyzed three-component domino reactions in the regioselective synthesis of novel densely functionalized pyrazolo[3,4-b]pyridines

Abstract

The L-proline-catalyzed three-component synthesis of novel 3-methyl-1-aryl-1H-pyrazolo[3,4-b]pyridines in good yields from the reaction of 3-methyl-1-aryl-1H-pyrazol-5-amines, 1,3-dicarbonyl compounds and aromatic aldehydes in ethanol is described. This domino transformation presumably involves the formation of two C–C bonds and one C–N bond in a single synthetic operation.