Synthesis of new Pd(NHC)-PEPPSI type complexes as catalysts toward C-C cross-coupling reactions

Abstract

• A series of palladium- N -heterocyclic carbene complexes were synthesized and characterized. • Pd-NHC complexes used as catalyst the C-C cross-coupling reactions. • They exhibited were found significantly active as catalysts toward these reactions. The goal of our research is to synthesis homogeneous catalysts, for which we take start from two novel precursors of 1-(3-methyloxetane-3-yl)benzimidazole and 5,6-dimethyl-1-((3-methyloxetane-3-yl)benzimidazole. A series of ligands containing 1,3-disubstituted benzimidazolium salts were synthesized from the corresponding precursors to form N-heterocyclic carbene (NHC) ligands. Furthermore, four new Pd(NHC)-PEPPSI type complexes were synthesized from these ligands. The structure elucidation of all the synthesized ligands, and complexes was confirmed by various spectroscopic techniques such as NMR, FT-IR. The compounds 1b, 2b, 3a, 3d were confirmed by the X-ray technique. All these complexes were found significantly active as catalysts toward the C-C cross-coupling reaction.