N-alkylbenzimidazolepalladium(II) complexes: Synthesis and their catalytic activities in direct C-H functionalization of pyrrole, furan and 2-acetylthiophene

Abstract

Herein, we reported the synthesis of six new palladium complexes (2a-2f) containing benzimidazole core and examined their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides. For this purpose, a new series of palladium(II) complexes bearing N-coordinated benzimidazole complexes have been synthesized and fully characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectroscopies. Additionally, the structures of the complexes 2a-2e have been characterized by X-ray crystallography. Further, direct arylation reactions, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides, and 1-methylpyrrole-2-carboxaldehyde, furfuryl acetate, 2-acetylfuran and 2-acetylthiophene. Moreover, moderate to high yields were obtained in the direct arylation of heteroarenes and aryl bromides under 1 % mol catalyst loading conditions.