Synthesis of Pd(II) complexes with P-N-OH ligands derived from 2(diphenylphosphine)-benzaldehyde and various aminoalcohols and their catalytic evaluation on Suzuki-Miyaura couplings in aqueous media

Abstract

The reactivity of a series of P-N-OH ligands derived from aminoalcohols and 2-(diphenylphosphine)-benzaldehyde was explored towards [Pd(COD)Cl-2] leading to a series of Pd(II) complexes having the ligands behaving either in a bidentate P-N or a tridentate P-N-OH manner. The complexes were fully characterized including the unequivocal determination of the molecular structures of all compounds by single crystal X-ray diffraction analysis. Interestingly, the ligands bearing alpha-substituted amines bind to the metal in a tridentate fashion through the P, N and OH atoms, while the ligand having the unsubstituted amine coordinated to Pd(II) center in a P-N bidentate manner. Furthermore, the catalytic activity of these complexes was explored in Suzuki-Miyaura couplings promoted by microwaves in aqueous media, affording yields up to 91% of biphenyls in 5 min.