Palladium(II)-N-heterocyclic carbene-catalyzed direct C2-or C5-arylation of thiazoles with aryl bromides

Herein we report a series of new benzimidazolium chlorides as N-heterocyclic carbene (NHC) ligand and their corresponding palladium(II)-NHC complexes with the general formula [PdCl2(NHC)(2)] were synthesized. All new compounds were characterized by H-1 NMR, C-13 NMR, IR spectroscopy and elemental analysis techniques. The catalytic activity of palladium(II)-NHC complexes was investigated in the direct C2- or C5-arylation of thiazoles with aryl bromides in presence of palladium(II)-NHC at 150(degrees)C for 1 h. These complexes exhibited the good catalytic performance for the direct arylation of thiazoles. The arylation of thiazoles regioselectively produced C2- or C5-arylated thiazoles in moderate to high yields. (C) 2018 Published by Elsevier Ltd.