Palladium(II) N-heterocyclic carbene complexes as catalysts for the direct arylation of pyrrole derivatives with aryl chlorides

[Display omitted] •The new Ag(I) and Pd(II)-NHC complexes were prepared.•These complexes were characterized by elemental analysis, IR, 1H, 13C NMR spectroscopy.•The new PdII complexes were tested as catalysts in direct arylation of pyrrole derivatives. Silver(I) N-heterocyclic carbene complexes were synthesized in good yields by the reactions of 1,3-dialkylperhydrobenzimidazolyum salts with silver(I) oxide and used as transmetallation reagents for the synthesis of palladium(II) N-heterocyclic carbene complexes. All of the complexes were characterized using elemental analysis, 1H NMR and 13C NMR spectroscopy. The catalytic activity of Pd(II)-NHC complexes in the direct arylation of pyrrole derivatives was investigated. These Pd(II)-NHC complexes showed the good catalytic performance for the direct arylation of pyrrole derivatives with readily available and inexpensive aryl chlorides. The arylation reactions regioselectively produced C2- or C5-arylation products in moderate to good yields by using 1mol% of the palladium complex.