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-pyridine-carboxaldehyde 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.