Two efficient ligand-assisted systems of two different ionic Schiff base ligands for palladium chloride catalyzed in Suzuki-Miyaura reaction

Abstract

The bis- methyl imidazolium chloride-salophen Schiff base ligand as cationic Schiff base ligand (L1) was synthesized by the reaction of methyl imidazoliumsalicylaldehyde chloride (S1) and phenylendiamine. The phenylendiamine was also reacted by monosodium 5-sulfonatosalycilaldehyde (S2) to give the bis-sodium sulfonate-salophen Schiff base ligand (L2) as the anionic ligand. These two ligands were characterized by the 1H-NMR, 13C-NMR, IR, UV–visible and mass spectroscopy, as well as elemental analysis. The ligand assisted PdCl2 catalyst was investigated in the Suzuki-Miyaura reaction by using the L1 and L2 as cationic and anionic Schiff base ligands and different reaction conditions such as temperature, solvent and mol% of PdCl2 were optimized. The results revealed that the anionic ligand assistance had a better activity for the catalytic system of PdCl2 in Suzuki-Miyaura reaction. Two ionic Schiff base ligands (bis- methyl imidazolium chloride-salophen as cationic and bis-sodium solphonate-salophen as anionic Schiff base ligands) were synthesized. The ligand-assisted PdCl2 catalyst was investigated in the Suzuki-Miyaura reaction by using these ionic Schiff base ligands and the results revealed that the anionic ligand-assisted had a better activity for the catalytic system of PdCl2 in Suzuki-Miyaura reaction.