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

Abstract

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.