Dichlorido(3-chloropyridine-N)[1,3-dialkylbenzimidazol-2-ylidene]palladium(II) complexes: Synthesis, characterization and catalytic activity in the arylation reaction

•PEPPSI themed six novel palladium N-heterocyclic carbene complexes were synthesized.•Their structures were characterized by elemental analysis and spectroscopic methods.•These complexes were tested as catalysts in the direct arylation and they exhibited high catalytic activities.

Six novel Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation (PEPPSI) themed palladium N-heterocyclic carbene (Pd-NHC) complexes (2a–f) were synthesized in good yields from the reaction of 1,3-dialkylbenzimidazolium salts with PdCl2 in the presence of K2CO3 as base in 3-chloropyridine. These synthesized complexes were characterized by means of elemental analysis, FT-IR, 1H and 13C NMR spectroscopic methods. The fully characterized novel complexes (2a–f) were tested as catalysts in the direct arylation of 2-n-propylthiazole, 2-n-butylthiophene and 2-n-butylfuran with different aryl bromides at 130 °C for 1 h. The complexes exhibited fairly high catalytic activities under the given conditions. The highest conversions were achieved when complexes 2a, 2e and 2f were used as catalysts in direct arylation.

Graphical abstractPyridine Enhanced Precatalyst Preparation, Stabilization and Initiation (PEPPSI) themed six novel palladium N-heterocyclic carbene (Pd-NHC) complexes (2a–f) were synthesized and characterized by elemental analysis and spectroscopic methods. These novel complexes (2a–f) were tested as catalysts in the direct arylation of 2-n-propylthiazole, 2-n-butylthiophene and 2-n-butylfuran with different aryl bromides at 130 °C for 1 h. These complexes exhibited high catalytic activities.Figure optionsDownload full-size imageDownload as PowerPoint slide