Role of substituents present in bidentate ligand frame of Cu(I) catalysts on Sonogashira cross coupling reactions

Abstract Cu(I) catalysts {[Cu(L1−4)Cl(PPh3)] where L1−4 = condensed product of 2-(1-phenylhydrazinyl)-pyridine with different benzaldehydes} were synthesized, characterized by 1H, 31P NMR, UV–Vis and IR techniques. Complex 2 structure was authenticated by single crystal X-ray method. Different electron donating and withdrawing substituents are present in the ligand frame of Cu(I) catalysts and their role on Sonogashira reaction was investigated. The efficiency order of catalysts for the coupling reaction was found to be 2 > 1>3 > 4, clearly indicated the role of substituents present in the ligand frame was useful to effectively catalyze the Sonogashira reaction. The products were characterized using 1H and 13C NMR.