Palladium N-Heterocyclic Carbene Catalysts for the Ultrasound-Promoted Suzuki-Miyaura Reaction in Glycerol

Abstract

Novel palladium N-heterocyclic-carbene (NHC)-based complexes with 3,4,5-trimethoxybenzyl, alkyl and sulfonate N-substituents were obtained and fully characterized. The new complexes were used as pre-catalysts in the Suzuki–Miyaura coupling of various aryl halides/boron sources in glycerol under pulsed-ultrasound (P-US) activation. High yields were obtained under mild reaction conditions, without formation of undesired by-products. The pure final cross-coupling products were easily recovered without column chromatography and the catalytic/solvent system could be recycled. TEM (transmission electron microscopy) and XPS (X-ray photoelectron spectroscopy) were used to characterize the nanoparticles and to investigate the fate of the catalysts.