Palladium(II) Complexes Bearing a Mixed Set of aNHC/Py/PR3/I2 Ligands: Applications in α-Arylation of Amide and Suzuki-Miyaura Coupling Reactions

Abstract

• PEPPSI type complexes with MIC donor ligand. • [Pd(MIC)(PR 3 )I 2 ] type complexes featuring mixed a NHC/PPh 3 /PCy 3 donor ligands as highly efficient catalysts. • α-arylation of oxindole. • Suzuki-Miyaura cross coupling reactions. Complexes possessing abnormal or mesoionic carbene ( a NHC or MIC) ligands are finding widespread applicability in organometallic chemistry owing to their various catalytic applications. Palladium(II) complexes bearing a mixed a NHC/Py/PR 3 /I 2 (R = Ph, Cy) donor set are presented starting from a biphenyl derived triazolium salt. The complexes have been characterized by NMR spectroscopy and ESI mass spectrometry. Two complexes have also been structurally characterized by single crystal XRD. The Pd II complexes have been tested as potent precatalysts for α-arylation of oxindole and Suzuki-Miyaura cross coupling reactions. Different donor ligands such as pyridine, 3-chloropyridine, 4-methoxypyridine, PPh 3 and PCy 3 have been used to compare the catalytic activities. The Pd II complexes containing mixed a NHC/PR 3 /I 2 donor set appeared to be more active catalysts when compared with the complexes bearing mixed a NHC/Py/I 2 donor set in both catalytic transformations.