Magnetically separable graphene oxide anchored sulfonic acid: a novel, highly efficient and recyclable catalyst for one-pot synthesis of 3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles in deep eutectic solvent under microwave irradiation

Abstract

Magnetically separable graphene oxide anchored sulfonic acid (Fe₃O₄–GO–SO₃H) nanoparticles were prepared and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) techniques. The synthesized heterogeneous material was found to exhibit high catalytic activity for synthesis of 3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles via one-pot, three-component reaction of 1-phenyl-3-(pyridin-3-yl)-1H-pyrazol-5-amine with 3-oxo-3-(pyridin-3-yl)propanenitrile and aldehydes using choline chloride (ChCl)/glycerol as a green solvent under microwave irradiation. The catalytic system can be successfully reused eight times with no significant loss of its catalytic performance.