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    N-Heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation of heteroarene derivatives with aryl bromides: synthesis, and antimicrobial and antioxidant activities
    (Royal Soc Chemistry, 2021) Hamdi, N.; Slimani, I.; Mansour, L.; Alresheedi, Faisal; Gurbuz, N.; Ozdemir, I.
    In this study, a series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides 2a-g with two nitrogen atoms substituted by different alkyl groups were synthesized in high yields as N-heterocyclic carbene (NHC) precursors. These benzimidazolium salts were then converted into the corresponding Pd-NHC complexes of the PEPPSI family (PEPPSI = pyridine-enhanced precatalyst preparation, stabilization, and initiation) 3a-g. The structures of all compounds were characterized by H-1 nuclear magnetic resonance (NMR) spectroscopy, C-13 NMR spectroscopy, infrared spectroscopy, and elemental analysis, which support the proposed structures. The structure of the 3c complex was determined by X-ray crystallography. More detailed structural characterization of the 3c complex was performed through single-crystal X-ray diffraction, which supports the proposed structures. The Pd-NHC-PEPPSI complexes were used as catalysts in the direct C-5-arylation of 2-acetyl furan, 2-acetylthiophene, and 2n-propylthiazole with different aryl bromides. These complexes exhibited moderate-to-high catalytic activities and selectively at the C-5 position. Furthermore, the Pd-NHC-PEPPSI complexes were evaluated for their potential antibacterial properties against a panel of bacterial strains, such as Micrococcus luteus, Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa. The Pd-NHC-PEPPSI complex 3f showed better activity than ampicillin against Micrococcus luteus, with an MIC of 0.035 mg mL(-1). In addition, the antioxidant activities of the complexes 3d and 3f showed considerable free radical scavenging activity.
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    N-Heterocyclic carbene-Pd(II)-PPh3 complexes as a new highly efficient catalyst system for the Sonogashira cross-coupling reaction: Synthesis, characterization and biological activities
    (Taylor & Francis Ltd, 2018) Boubakri, L.; Mansour, L.; Harrath, A. H.; Ozdemir, I.; Yasar, S.; Hamdi, N.
    A novel series of N-heterocyclic carbene-phosphine palladium(II) complexes has been synthesized and fully characterized by IR, H-1 NMR, C-13 NMR, and P-31 NMR spectroscopies, and elemental analysis. The new N-heterocyclic carbene (NHC)-phosphine palladium(II) complexes 3a-h have been easily prepared by the reaction of the corresponding PEPPSI (pyridine-enhanced precatalyst preparation stabilization and initiation) complexes 2a-h and triphenylphosphine in dichloromethane in high yields. These complexes were applied as catalyst precursors which efficiently catalyzed Sonogashira reactions between aryl bromides and phenylacetylene to afford the corresponding products in good yields. The bulky NHC-Pd-PPh3 complexes 3 were tested against Gram-positive and Gram-negative bacteria to study their biological activity. All the complexes exhibit antibacterial against these organisms. Investigation of the antiacetylcholinesterase activity of the studied complexes showed that compounds 3a and 3b exhibited moderate activity at 100 mu g mL-1 and product 3b is the most active.
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    Synthesis and catalytic applications of palladium N-heterocyclic carbene complexes as efficient pre-catalysts for Suzuki-Miyaura and Sonogashira coupling reactions
    (Royal Soc Chemistry, 2017) Boubakri, L.; Yasar, S.; Dorcet, V.; Roisnel, T.; Bruneau, C.; Hamdi, N.; Ozdemir, I.
    A new palladium complex series with N-heterocyclic carbene (NHC), pyridine and phosphine ligands, PdCl2(L)NHC (2a-c)(L = NHC), PdCl2(L-1)NHC(3a-c)(L-1 = pyridine), PdCl2(L-2)NHC(4a-c)(L-2 = triphenyl-phosphine) was synthesised and fully characterized. The catalytic activities of these complexes were screened for the Sonogashira and Suzuki-Miyaura reactions between arylhalides and phenylacetylene, and phenylboronic acid, respectively. The results pointed out that the carbene/phosphine complexes 4a-c exhibited excellent catalytic activities as compared to 2a-c, 3a-c, and the well-known systems for the palladium-catalysed Sonogashira reaction. The reactivity of 4a-c in these preliminary Sonogashira coupling tests seems to be higher than that of previously reported catalytic systems based on Pd(NHC) moieties. These new palladium NHC complexes are among the first reported palladium catalysts that are efficient for catalysing the Sonogashira reaction from arylchloride substrates.