Catalytic application of zwitterionic palladium complexes in Mizoroki-Heck reactions using ionic liquid as solvent

摘要

New ligand precursors with different pendent alky chain length were obtained in a single step by reacting appropriate 1-alkyl-2-methyl-1H-imidazoles with chloroacetone in THF at 80 degrees C overnight. Zwitterionic palladium complexes were prepared by reacting PdCl2 with these new imidazole derivatives in DMF with the presence of pyridine and Cs2CO3 as base at room temperature for 5 h. These new compounds were characterized by H-1 and C-13{H-1} NMR spectroscopy, elemental analysis, and electrospray ionization mass spectrometry. They were effectively applied as recyclable catalysts for mediating Mizoroki-Heck reactions in ionic liquids. Transmission emission microscopy revealed that palladium nanoparticles were formed during the catalytic process. (C) 2015 Elsevier B.V. All rights reserved.