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    N-Heterocyclic carbene-palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides
    (Beilstein-Institut, 2013) Ozdemir, Ismail; Gurbuz, Nevin; Kaloglu, Nazan; Dogan, Oznur; Kaloglu, Murat; Bruneau, Christian; Doucet, Henri
    New Pd-NHC complexes have been synthesized and employed for palladium-catalyzed direct arylation of pyrrole derivatives by using electron-deficient aryl chlorides as coupling partners. The desired coupling products were obtained in moderate to good yields by using 1 mol % of these air-stable palladium complexes. This is an advantage compared to the procedures employing air-sensitive phosphines, which have been previously shown to promote the coupling of aryl chlorides with heteroarenes.
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    N-Heterocyclic Carbenes: Useful Ligands for the Palladium-Catalysed Direct C5 Arylation of Heteroaromatics with Aryl Bromides or Electron-Deficient Aryl Chlorides
    (Wiley-V C H Verlag Gmbh, 2010) Ozdemir, Ismail; Gok, Yetkin; Ozeroglu, Oezlem; Kaloglu, Murat; Doucet, Henri; Bruneau, Christian
    New Pd-N-heterocyclic carbene complexes have been prepared and employed for palladium-catalysed direct arylation of heteroaromatic derivatives by using aryl halides. These catalyst precursors promote the coupling of challenging aryl halides such as deactivated or congested aryl bromides and also activated aryl chlorides. This procedure employs only 1 mol-% of an air-stable palladium complex. This is a practical advantage over the procedures that employ palladium attached to air-sensitive phosphane ligands, which are often used to promote the coupling of such aryl halides.
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    Palladium Complexes with Tetrahydropyrimidin-2-ylidene Ligands: Catalytic Activity for the Direct Arylation of Furan, Thiophene, and Thiazole Derivatives
    (Amer Chemical Soc, 2015) Karaca, Emine Ozge; Gurbuz, Nevin; Ozdemir, Ismail; Doucet, Henri; Sahin, Onur; Buyukgungor, Orhan; Cetinkaya, Bekir
    The synthesis and characterization of novel 1,3-benzyl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N-hetero-cyclic carbene palladium(II) complexes (1a-d) were described. The crystal structure of trans-dichlorobis[1,3-bis(4-methylbenzyl)-3,4,5,6-tetrahydropyrimidin-2-ylidend- palladium(II) was presented. Pd(II) complexes 1a-d were tested as catalysts in the direct C5 or C2 arylation of furans, thiophenes, and thiazoles, with various aryl bromides at 150 degrees C for 1 h. These complexes exhibited moderate to high catalytic activities under the given conditions.
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    PEPPSI-Type Palladium-NHC Complexes: Synthesis, Characterization, and Catalytic Activity in the Direct C5-Arylation of 2-Substituted Thiophene Derivatives with Aryl Halides
    (Wiley-V C H Verlag Gmbh, 2017) Kaloglu, Murat; Ozdemir, Ismail; Dorcet, Vincent; Bruneau, Christian; Doucet, Henri
    Six benzimidazolium salts, having two nitrogen atoms substituted by various alkyl groups, have been synthesized in high yields. The benzimidazolium salts readily converted into the corresponding PEPPSI-type palladium-NHC complexes (PEPPSI = pyridine-enhanced precatalyst preparation, stabilization, and initiation). The structures of all compounds have been characterized by H-1 NMR, C-13 NMR, and IR spectroscopy, as well as elemental analysis techniques, which support the proposed structures. The molecular structure of one complex has been determined by single-crystal X-ray diffraction. The catalytic activity of the PEPPSI-type palladium-NHC complexes has been evaluated with respect to the direct C5-arylation of 2-substituted thiophene derivatives with various aryl halides. This arylation occurs efficiently and selectively at the C5-position of 2-substituted thiophene derivatives.
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    Synthesis of N-heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation
    (Elsevier Science Sa, 2018) Kaloglu, Nazan; Kaloglu, Murat; Tahir, Muhammad Nawaz; Arici, Cengiz; Bruneau, Christian; Doucet, Henri; Dixneuf, Pierre H.
    A series of benzimidazolium salts having their two nitrogen atoms substituted by bulky groups have been synthesized. The benzimidazolium salts were readily converted into the corresponding palladium-NHC-PEPPSI complexes with general formula [PdBr2(NHC) (Py)], (NHC = N-heterocyclic carbene; PEPPSI = pyridine-enhanced precatalyst preparation, stabilisation, and initiation). The structures of all new compounds were characterized by NMR, IR spectroscopy and microanalysis techniques, which support the proposed structures. The molecular structure of complex 2g was determined by singlecrystal X-ray diffraction study. Next, the palladium-NHC-PEPPSI complexes were used as catalysts in the direct C5-arylation of 1-methylpyrrole-2-carboxaldehyde by aryl halides. These complexes exhibited moderate to high catalytic activities and gave C-H activation selectively at the C5-position of 1methylpyrrole- 2-carboxaldehyde. Both electron-donating and electron-withdrawing substituents were well tolerated with catalytic systems based on these complexes, even non-activated aryl chlorides such as chlorobenzene or 4-chlorotoluene were coupled with pyrrole in moderate yields. (C) 2017 Elsevier B.V. All rights reserved.