N-Heterocyclic Carbene Palladium Complexes with Different N-Coordinated Ligands: Comparison of Their Catalytic Activities in Suzuki-Miyaura and Mizoroki-Heck Reactions

Abstract

In this paper, we have reported the synthesis and catalytic activities of four new anthracene substituted imidazole-based palladium N-heterocyclic carbene complexes. The synthesized complexes, 2a–d, were stabilized with different N-heterocycles, namely pyridine, N-methylimidazole, N-vinylimidazole and 4,5-dimethylthiazole, respectively. The complexes were completely characterized using 1H NMR, 13C NMR, IR, LC–MS spectroscopic methods and elemental analyses. The crystal structures of 2a, 2c and 2d were also reported. The catalytic activities of all the complexes were tested for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions in aqueous medium. According to the results, for the Suzuki-Miyaura reaction, the pyridine bearing complex 2a, and for the Mizoroki-Heck reaction, the 4,5-dimethylthiazole bearing complex 2d were found to be the most active catalysts. © 2019 Elsevier Ltd