N-heterocyclic carbene-palladium(II) complexes with benzoxazole or benzothiazole ligands: Synthesis, characterization, and application to Suzuki–Miyaura cross-coupling reaction

• Four new N-heterocyclic carbene-palladium(II) complexes based on benzoxazole or benzothiazole ligands have been conveniently synthesized.
• All of the new complexes have been well characterized.
• The catalytic activity of Pd(II) complexes in the Suzuki–Miyaura coupling of aryl as well as benzyl chlorides with arylboronic acids are investigated.

A series of novel N-heterocyclic carbene-palladium(II) complexes 3 were conveniently prepared from commercially available imidazolium salts, palladium chloride, and benzoxazole or benzothiazole in one step. All of the new complexes have been fully characterized by elemental analysis, 1H, 13C NMR, and IR spectra. In addition, the molecular structures of complexes 3a-d have also been determined by X-ray single-crystal diffraction. The obtained palladium(II) catalysts showed efficient catalytic activity toward the Suzuki–Miyaura coupling of aryl as well as benzyl chlorides with arylboronic acids. Under the optimal reaction conditions, the expected biaryl products were obtained in moderate to high yields.

Figure optionsDownload as PowerPoint slide