NCN palladium pincer via transmercuration. Synthesis of [2-(2-oxazoliny)-6-(2-pyridyl)] phenylpalladium(II) chloride and its catalytic activity in Suzuki coupling

The unsymmetrical NCN ligand 1-(2-oxazolinyl)-3-(2-pyridyl)benzene 6 was synthesized starting from m-bromotoluene after a series of transformations. The reaction of 6 and mercury (II) acetate resulted in mercurial derivative 7 which was transformed into the corresponding NCN palladium pincer 8 via transmercuration. The ultraviolet spectra of 6–8 in acetonitrile were also studied. The structures of 6 and 8 were further confirmed by X-ray single crystal diffraction. The carbon–carbon cross coupling reactions between aryl halides and phenylboronic acid catalyzed by 8 were investigated. The results indicate that this palladium pincer is more highly active to the coupling of aryl bromides than aryl chlorides.