Synthesis of Pd-II Triazolylidene Complexes via an Unusual C-sp2-C-sp2 Decoupling Reaction: Applications in alpha-Arylation of Amide and Suzuki-Miyaura Coupling Reactions

摘要

Mononuclear Pd-II complexes bearing mixed MIC/Py/PPh3 donor set ligands are presented starting from a bis-triazolium salt featuring 4,4'-substitution pattern of central biphenyl ring. The mononuclear PEPPSI (pyridine enhanced precatalyst preparation, stabilization and initiation) type complexes bearing triazolylidene donor ligand have been synthesized via an unusual C-sp2-C-sp2 decoupling reaction. The complexes have been characterized by H-1, C-13{H-1} NMR spectroscopy and mass spectrometry. Two of the complexes have also been structurally characterized by single crystal XRD. All the complexes appeared as active precatalysts in alpha-arylation of amide and Suzuki-Miyaura coupling reactions. Catalytic outcomes clearly indicate the superior activities of the Pd-II complexes with mixed MIC/PPh3 donor set ligands compared to the corresponding PEPPSI type complexes in alpha-arylation of oxindole.