A Novel Synthesis of 3,4-Discubstituted-1H-pyrazolo[3,4-b]quinolines

Abstract A simple and efficient synthesis of pyrazolo[3,4-b] quinolines is described. The synthesis involves reaction of 2-amino-3-cyanoquinoline-4-carboxylates(1) with hydrazine hydrate to give regioselectively only pyrazolo[3,4-b]quinolines (2). No formation of pyridazino quinolines (3) is observed.