4,5-Dihydro-imidazol-2-ylidene-linked palladium complexes as catalysts for the direct C-H bond arylation of azoles

Kaloğlu M., Özdemir N., Özdemir İ.

APPLIED ORGANOMETALLIC CHEMISTRY, 2022 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1002/aoc.6551
  • Dergi Adı: APPLIED ORGANOMETALLIC CHEMISTRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, BIOSIS, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, Metadex, DIALNET, Civil Engineering Abstracts
  • Anahtar Kelimeler: 4, 5-Dihydro-imidazol-2-ylidene, direct C-H bond arylation, N-heterocyclic carbene, palladium, PEPPSI, CROSS-COUPLING REACTIONS, HETEROCYCLIC CARBENE COMPLEXES, RECENT PROGRESS, ARYL CHLORIDES, HETEROAROMATIC-COMPOUNDS, PEPPSI COMPLEXES, FUNCTIONALIZATION, HALIDES, HETEROARENES, IMIDAZOLES
  • İnönü Üniversitesi Adresli: Evet

Özet

Recently, PEPPSI-type palladium-complexes bearing N-heterocyclic carbene (NHC) ligand have commonly been used as the effective catalysts in the direct arylation of heteroaromatic compounds. In most of previous studies catalyzed by such complexes, unsaturated ring carbene ligands such as benzo[d]imidazol-2-ylidene and imidazol-2-ylidene were used. However, the use of saturated ring carbene ligands such as 4,5-dihydro-imidazol-2-ylidene has been highly limited. Therefore, in this study, four novel 4,5-dihydro-1H-imidazolium salts were synthesized as saturated ring carbene precursors. Then, well-defined air- and moisture-stable four novel PEPPSI-type palladium-complexes with 4,5-dihydro-imidazol-2-ylidene ligands were prepared. All synthesized carbene precursors and palladium-complexes were structurally characterized by different spectroscopic and analytical techniques. Further structural characterization of two of the palladium-complexes was performed by single-crystal X-ray diffraction. Next, the palladium-complexes were tested in the direct arylation of azoles such as 4,5-dimethylthiazole and 1-methyl-1H-imidazole with (hetero)aryl halides in presence of 1 mol% catalyst loading at 120 degrees C. The results showed that these novel palladium complexes are effective catalysts.