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    An efficient palladium catalyzed mizoroki-heck cross-coupling in water: synthesis, characterization and catalytic activities
    (Pergamon-Elsevier Science Ltd, 2024) Bensalah, Donia; Mansour, Lamjed; Sauthier, Mathieu; Gurbuz, Nevin; Ozdemir, Ismail; Gatri, Rafik; Hamdi, Naceur
    A series of new palladium complexes known as PEPPSI-type complexes 3 were successfully synthesized by reacting benzimidazolium salts 2a -e , potassium carbonate (K 2 CO 3 ), and palladium chloride (PdCl 2 ) in pyridine for 16 h at 80 degrees C. Both the benzimidazolium salts 2a -e and the resulting complexes 3 were characterized through spectroscopic data and elemental analysis. The Mizoroki-Heck coupling reaction, catalyzed by the homogeneous Pd, was effectively carried out in water without the need for any additional substances under aerobic conditions. The optimization of various key reaction parameters was performed to enhance the yield of the desired cross coupling product. The catalytic performance of these complexes in a catalytic system containing palladium complexes 3a , Et 3 N, and H 2 O was evaluated in the Mizoroki-Heck coupling reaction. The PEPPSI-type palladium complex 3a /Et 3 N/H 2 O/98 degrees C catalyst system exhibited high activity, with a turnover frequency (TOF) ranging from 12 to 14 /hour towards achieving the excellent yield of the Mizoroki-Heck coupling products for a wide range of electron withdrawing as well as electron donating aryl bromide and chlorides in shortest reaction time.
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    Palladium(ii)/N-heterocyclic carbene (NHC) catalyzed direct C-H arylation of heteroarenes with different aryl bromides and chlorides
    (Royal Soc Chemistry, 2023) Bensalah, Donia; Mansour, Lamjed; Sauthier, Mathieu; Gurbuz, Nevin; Ozdemir, Ismail; Koko, Waleed S.; Gatri, Rafik
    The growing interest of industry in the field of bi(hetero)arene compounds motivated us to synthesize these compounds via a homogeneous catalytic route using Pd PEPPSI-type complexes through direct arylation. In this study, new Pd PEPPSI-type complexes bearing NHC spectator ligands were synthesized and characterized using spectroscopic techniques, such as (HNMR)-H-1, C-13 NMR, MS spectrometry, FTIR spectroscopy and elemental analysis (PEPPSI = pyridine enhanced precatalyst preparation stabilization and initiation). All the synthesized Pd(II) complexes were stable. The catalytic properties of these complexes were evaluated in the direct C-5 mono-arylation of furan, 2-acetylthiophene and N-methylpyrrole-2-carboxaldehyde derivatives with a wide variety of (hetero)aryl halides. This environmentally attractive procedure was found to be tolerant of a wide variety of functional groups on the aryl halides and good yields were obtained in the presence of 1 mol% catalyst loading at 150 degrees C for 2 hours. In addition, the conversions for substrates containing electron-withdrawing groups were higher than those for substituents containing electron-donating groups.
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    Plausible PEPPSI catalysts for direct C-H functionalization of five-membered heterocyclic bioactive motifs: synthesis, spectral, X-ray crystallographic characterizations and catalytic activity
    (Royal Soc Chemistry, 2023) Bensalah, Donia; Mansour, Lamjed; Sauthier, Mathieu; Gurbuz, Nevin; Ozdemir, Ismail; Beji, Lotfi; Gatri, Rafik
    In this study, a series of benzimidazolium salts were synthesized as asymmetric N-heterocyclic carbene (NHC) precursors. Nine novel palladium complexes with the general formula [PdX2(NHC)(pyridine)] were synthesized using benzimidazolium salts in the PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) theme. All synthesized Pd(ii) complexes are stable. The synthesized compounds were thoroughly characterized by respective spectroscopic techniques, such as 1HNMR, 13C NMR, FTIR spectroscopy, X-ray crystallography and elemental analysis. The geometric structure of the palladium N-heterocyclic carbene has been optimized in the framework of density functional theory (DFT) using the B3LYP-D3 dispersion functional with LANL2DZ as a basis set. The on/off mechanism of pyridine assisted Pd-NHC complexes made them the best C-H functionalized catalysts for regioselective C-5 arylated products. Five membered heterocyclic compounds such as 2-acetyl furan, furfuryl acetate 2-acetylthiophene and N-methylpyrrole-2-carboxaldehyde were treated with numerous aryl bromides and arylchlorides under optimal catalytic reaction conditions. Interestingly, all the prepared catalysts possessed essential structural features that facilitated the formation of desired coupling products in quantitative yield with excellent selectivity. The arylation reaction of bromoacetophenone was highly catalytically active with only 1 mol% catalyst loading at 150 degrees C for 2 hours. To check the efficiency of the synthesized complexes, three different five member heterocyclic substrates (2-acetylfuran, 2-acetylthiophen, 2-propylthaizole) were tested with a number of aryl bromides bearing both electron-donating and electron-withdrawing groups on para position. The data in Tables 2-4. Indicated that electron-donating groups on the para position of aryl halide decreased the catalytic conversion while electron-withdrawing groups increased the catalytic conversion this was due to the high nucleophilicity of the electron-donating substituents. In this study, a series of benzimidazolium salts were synthesized as asymmetric N-heterocyclic carbene (NHC) precursors.
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    Synthesis of palladium complexes containing benzimidazole core and their catalytic activities in direct C-H functionalization of five-membered heterocyclic bioactive motifs
    (Elsevier, 2024) Touj, Nedra; Bensalah, Donia; Mansour, Lamjed; Sauthier, Mathieu; Gurbuz, Nevin; Ozdemir, Ismail; Hamdi, Naceur
    Herein, we reported the synthesis of nine new PEPPSI-Pd(II)-N-heterocyclic carbene (NHC) complexes 3a-h containing benzimidazole core and examined their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides and arylchlorides. Nine new Pd benzimidazole complexes were synthesized and their structures were elucidated by 1H and 13C NMR spectroscopy, FT-IR spectroscopy, and elemental analysis methods. In the 13C NMR spectra, NCHN peaks of Pd(II) complexes were observed between 159.7-161.5 ppm. Further, direct arylation reaction, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides and chlorides, and 2-acetyl furan, and furfuryl acetate 2-acetylthiophene and N-methylpyrrole-2- carboxaldehyde. Moreover, moderate to hig yields were obtained in the direct arylation of heteroarenes and aryl bromides under 1 mol% catalyst loading at 150 degrees C for 2 h loading conditions. The results showed that electron-donating and electron-withdrawing substituents on the aryl halides might produce coupling products in good yields in the presence of complexes 2a-d. Taken together, our findings are expected to contribute to the synthesis and design of palladium complexes containing benzimidazole core structures.
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    Synthesis, Characterization, Antimicrobial Properties, and Antioxidant Activities of Silver-N-Heterocyclic Carbene Complexes
    (Hindawi Ltd, 2023) Bensalah, Donia; Gurbuz, Nevin; Ozdemir, Ismail; Gatri, Rafik; Mansour, Lamjed; Hamdi, Naceur
    The emergence of antimicrobial resistance has become a major handicap in the fight against bacterial infections, prompting researchers to develop new, more effective, and multimodal alternatives. Silver and its complexes have long been used as antimicrobial agents in medicine because of their lack of resistance to silver, their low potency at low concentrations, and their low toxicity compared to most commonly used antibiotics. N-Heterocyclic carbenes (NHCs) are widely used for coordination of transition metals, mainly in catalytic chemistry. In this study, several N-alkylated benzimidazolium salts 2a-j were synthesized. Then, the N-heterocyclic carbene (NHC) precursor was treated with Ag2O to give silver (I) NHC complexes (3a-j) at room temperature in dichloromethane for 48 h. Ten new silver-NHC complexes were fully characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and LC-MSMS (for complexes) techniques. The antibacterial and antioxidant activities of salt 2 and its silver complex 3 were evaluated. All of these complexes were more effective against bacterial strains than comparable ligands. With MIC values ranging from 6.25 to 100 g/ml, the Ag-NHC complex effectively showed strong antibacterial activity. Antioxidant activity was also tested using conventional techniques, such as 2, 2-diphenyl-1-picrylhydrazine (DPPH) and hydrogen peroxide scavenging assays. In DPPH and ABTS experiments, compounds 3a, 3b, 3c, 3e, 3g, and 3i showed significant clearance.