CSA Catalyzed Multi-component Synthesis of Polycyclic Pyrazolo[4,3-e]pyridines Under Ultrasonic Irradiation and Their Antioxidant Activity

Abstract

New fused pyrazolo[4,3-e]pyridines were obtained by three-component reaction of 1,3-dimethyl-1H-pyrazol-5-amine or 3-phenyl-1H-pyrazol-5-amine, aromatic aldehydes and indan-1,3-dione in the presence of camphor-10-sulfonic acid (CSA) as an effective catalyst under ultrasound promoted conditions. The antioxidant activity of the pyrazolopyridine compounds 4b, 5c, 5e, 7a, 7b and 7c were determined.