Phosphine-Free Hydrazone−Pd Complex as the Catalyst Precursor for a Suzuki−Miyaura Reaction under Mild Aerobic Conditions

Glyoxal bis(N-methyl-N-phenylhydrazone) (1) and its related compounds such as 2-pyridinecarboxaldehyde N-methyl-N-phenylhydrazone (3) were prepared and examined as ligands for the Suzuki−Miyaura cross-coupling reaction of aryl halides and arylboronic acids. We found phosphine-free catalysts, such as Pd(OAc)2/hydrazone ligand 1 or 3, to be efficient catalysts for a variety of substrates to produce the coupling products in good yields.