Microwave-assisted one-pot synthesis in water of carbonylpyrazolo[3,4-b]pyridine derivatives catalyzed by InCl3 and sonochemical assisted condensation with aldehydes to obtain new chalcone derivatives containing the pyrazolopyridinic moiety

Abstract

Pyrazolo[3,4-b]pyridine derivatives have been synthesized via one-pot condensation of 3-methyl-1-phenyl-1H-pyrazolo-5-amine (1), formaldehyde (as paraformaldehyde) (2) and β-diketones (3) under microwave irradiation in aqueous media catalyzed by InCl₃. This process has been found to be useful in the preparation of new N-fused heterocycle products in good to excellent yields. Further treatment of pyrazolopyridines (4a and 4e) with aldehyde aromatics (5a–l) afforded chalcone analogs.