C–H functionalization of aromatic amines for azidation catalyzed by Betti base coordinated copper(ii) complexes under ultrasonication

Abstract

Five new Betti base copper(II) complexes (C1–C5) are successfully synthesized and characterized spectroscopically. X-ray diffraction analysis confirmed the square planar geometry of complex C4. Their catalytic application in the C–H functionalization of aromatic amines for azidation was successfully demonstrated under ultrasonication. Complex C5 showed better catalytic activity and produced 2-azidoaniline with a yield of 85%, which is higher than the existing methods; it also performed better than commercial catalysts, with a higher efficiency. The reaction involves a lower catalytic loading and a short reaction time. Control experiments were carried out to predict the reaction pathway. Based on the results, a plausible mechanism involving a free radical pathway accompanied by a single electron transfer mechanism is proposed. The substrate scope was also studied with different aromatic amines, and the corresponding azides were obtained successfully. All the synthesized azides were employed in click reactions to obtain the respective triazoles. The biological relevance of the triazoles was also explored successfully using molecular docking studies against SARS-CoV-2 main protease Omicron P132H.