- Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes
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A novel catalyst-free approach to benzoannulated oxygen-containing heterocycles from fluorinated oligophenylenes is reported. Unlike existing methods, the presented reaction does not require an oxygen-containing precursor and relies on an external oxygen source, potassium tert-butoxide, which serves as an O2? synthon. The radical nature of the reaction facilitates nucleophilic substitution even in the presence of strong electron-donating groups and enables de-tert-butylation required for the complete annulation. Also demonstrated is the applicability of the method to introduce five-, six-, and seven-membered rings containing oxygen, whereas multiple annulations also open up a short synthetic path to ladder-type O-heteroacenes and oligodibenzofurans.
- Feofanov, Mikhail,Akhmetov, Vladimir,Takayama, Ryo,Amsharov, Konstantin
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supporting information
p. 5199 - 5203
(2021/02/21)
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- Zirconium-redox-shuttled cross-electrophile coupling of aromatic and heteroaromatic halides
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Transition metal-catalyzed cross-electrophile coupling (XEC) is a powerful tool for forging C(sp2)–C(sp2) bonds in biaryl molecules from abundant aromatic halides. While the synthesis of unsymmetrical biaryl compounds through multimetallic XEC is of high synthetic value, the selective XEC of two heteroaromatic halides remains elusive and challenging. Herein, we report a homogeneous XEC method, which relies on a zirconaaziridine complex as a shuttle for dual palladium-catalyzed processes. The zirconaaziridine-mediated palladium (ZAPd)-catalyzed reaction shows excellent compatibility with various functional groups and diverse heteroaromatic scaffolds. In accord with density functional theory (DFT) calculations, a redox transmetallation between the oxidative addition product and the zirconaaziridine is proposed as the crucial elementary step. Thus, cross-coupling selectivity using a single transition metal catalyst is controlled by the relative rate of oxidative addition of Pd(0) into the aromatic halide. Overall, the concept of a combined reducing and transmetallating agent offers opportunities for the development of transition metal reductive coupling catalysis.
- Fu, Yue,Liu, Fang-Jie,Liu, Peng,Tang, Jian-Tao,Toste, F. Dean,Wu, Ting-Feng,Ye, Baihua,Zhang, Yue-Jiao
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supporting information
p. 1963 - 1974
(2021/07/07)
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- Synthesis of biaryl compounds via Suzuki homocoupling reactions catalyzed by metal organic frameworks encapsulated with palladium nanoparticles
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Heterogeneous homocoupling reactions of phenylboronic acids were greatly accelerated via Suzuki homocoupling reactions. In this work, a tandem route was designed which firstly one part of phenylboronic acids reacted with iodine to form iodobenzenes, then another part of phenylboronic acids coupled with iodobenzenes to produce biaryl compounds. The tandem reaction were catalyzed by a bifunctional heterogeneous catalyst of metal organic frameworks encapsulated with palladium nanoparticles (Pd?MOFs). This strategy for forming symmetric C-C bond between benzene rings has obvious advantages such as high efficiency, easy separation, good recyclability and no addition of toxic halogenated benzene.
- Bao, Yan-Sai,Cui, Xin-Yu,Han, Zheng-Bo,Li, Xin,Tang, Hong,Yang, Ming,Zhang, Yu-Yang,Zhao, Kun,Zhou, Mei-Li
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- Alumina-promoted oxodefluorination
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A simple protocol for the clean preparation of heterocyclic compounds containing dibenzofuran's core via oxodefluorination of fluoroarenes on activated γ-Al2O3 is reported. Alumina can be considered as a reliable oxygen source enabling one-pot substitution of fluorine atoms and yielding benzoannulated furan derivatives. The corresponding C-F bond activation is selective towards less stable C-Br/C-I and occurs under metal- A nd solvent-free conditions.
- Amsharov, Konstantin,Mikhail, Feofanov,Vladimir, Akhmetov
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p. 10879 - 10882
(2020/03/27)
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- Palladium/Sensory Component-Catalyzed Homocoupling Reactions of Aryl Halides
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A novel and efficient catalyst system was developed for homocoupling reactions of aryl halides. The catalyst system consists of Pd(OAc) 2and the peppery sensory component of tobacco leaves. This is the first time that a sensory component has been used in an organic reaction. Experiments using the catalyst system showed that the reactions proceeded smoothly under air in the absence of both an additional ligand and a reductant. Furthermore, the catalyst system can be applied to the coupling reactions of hetaryl iodides. Many functional groups (including a hydroxy group) are tolerated.
- Bai, Haixin,Bao, Fengyu,Chai, Guobi,Liu, Pengfei,Liu, Zhikai,Zhang, Haiyan,Zhang, Qidong
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supporting information
(2020/09/09)
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- Glucopyranoside-substituted imidazolium-based chiral ionic liquids for Pd-catalyzed homo-coupling of arylboronic acids in water
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Chiral ionic liquids (CILs) are widely used solvents and materials with prominent properties. Carbohydrate-derived imidazolium-based CILs represent a distinctive type of CILs possessing multiple chiral centers from natural chiral pool. Herein, a series of glucopyranoside-substituted imidazolium-based CILs (Glu-imi-CILs) were synthesized and evaluated as ligands for Pd-catalyzed homo-coupling reactions of arylboronic acids in water. The glucopyranoside substituent was instrumental for improving the catalytic activity of the resulting catalysts. Moreover, a Glu-imi-CIL with a free hydroxyl group for additional coordination was found to be the most efficient ligand. A series of symmetric biaryl compounds (13 examples) were synthesized from arylboronic acids by this method in high isolated yields (85?99percent).
- Huang, Zhiqiang,Kong, Lingfang,Li, Jing,Wu, Yue,Xue, Jun,Yuan, Yangyang,Zhou, Zhonggao
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- Efficient Pd-catalyzed oxidative homocoupling of arylboronic acids in aqueous NaClO
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An efficient, mild and practical method was developed for the synthesis of biaryls via the Pd-catalyzed oxidative homocoupling of aromatic/heteroaromatic boronic acids in aqueous NaClO.
- Li, Min-Xin,Tang, Yan-Ling,Gao, Hui,Mao, Ze-Wei
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supporting information
(2020/03/04)
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- Palladium-mediated radical homocoupling reactions: A surface catalytic insight
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In this contribution, we report a palladium nanoparticle-promoted reductive homocoupling of haloarenes that proceeds efficiently to produce corresponding bis-aryls in moderate to excellent yields using relatively low catalyst loading (1 mol%), and exhibits broad functional group tolerance. This work sheds light on how the surface state of Pd(0) nanoparticles plays a crucial role in the reactivity of catalytic systems. Notably, the appropriate choice of palladium salts for the preparation of the preformed nanocatalysts was a key parameter having a major impact on the catalytic activity; thus, the effect of halide anions on the reactivity of the as-prepared palladium nanoparticles could be assessed, with iodide anions being capable of inhibiting the corresponding homocoupling reaction. The homocoupling reaction mechanism has been further studied by means of radical trap and electron paramagnetic resonance (EPR) experiments, revealing that the reaction proceeds via radical intermediates. Taking into account these data, a plausible reaction mechanism based on single-electron transfer processes on the palladium nanoparticle surface is discussed.
- Favier, Isabelle,Toro, Marie-Lou,Lecante, Pierre,Pla, Daniel,Gómez, Montserrat
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p. 4766 - 4773
(2018/09/29)
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- The Rolling-Up of Oligophenylenes to Nanographenes by a HF-Zipping Approach
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Intramolecular aryl–aryl coupling is the key transformation in the rational synthesis of nanographenes and nanoribbons. In this respect the C?F bond activation was shown to be a versatile alternative enabling the synthesis of several unique carbon-based nanostructures. Herein we describe an unprecedentedly challenging transformation showing that the C?F bond activation by aluminum oxide allows highly effective domino-like C?C bond formation. Despite the flexible nature of oligophenylene-based precursors efficient regioselective zipping to the target nanostructures was achieved. We show that fluorine positions in the precursor structure unambiguously dictate the “running of the zipping-program” which results in rolling-up of linear oligophenylene chains around phenyl moieties yielding target nanographenes. The high efficiency of zipping makes this approach attractive for the synthesis of unsubstituted nanographenes which are difficult to obtain in pure form by other methods.
- Steiner, Ann-Kristin,Amsharov, Konstantin Y.
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supporting information
p. 14732 - 14736
(2017/10/23)
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- Pd(OAc)2 catalyzed homocoupling of arenediazonium salts in ionic liquids: Synthesis of symmetrical biaryls
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A facile, high yielding, and simple method for the synthesis of a library of symmetrical biaryls by homocoupling of arenediazonium salts is reported, employing catalytic amounts of Pd(OAc)2 and the readily available imidazolium ionic liquids (ILs), without oxidants, ligands, additives, or volatile solvents. Simple product isolation and recycling/reuse of the IL represent additional advantages of this method.
- Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 663 - 667
(2016/01/26)
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- Dimerization of Aryl Sulfonates by in situ Generated Nickel(0)
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A mild and user-friendly nickel-catalyzed method for the reductive homocoupling of aromatic tosylates is presented. The reaction proceeds between room temperature and 60 °C, with stable substrates (ArOTs) easily prepared from inexpensive and commercially available phenols or naphthols. It relies on a catalytic amount (10 mol%) of a robust catalyst (NiBr2bipy) that does not require the preparation of sensitive organometallic intermediates. Yields are good to excellent.
- Maddaluno, Jacques,Durandetti, Muriel
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p. 2385 - 2388
(2015/10/19)
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- The transition-metal-catalyst-free oxidative homocoupling of organomanganese reagents prepared by the insertion of magnesium into organic halides in the presence of MnCl2·2LiCl
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Organomanganese reagents were prepared by the insertion of magnesium into aryl halides in the presence of MnCl2·2LiCl. These organomanganese reagents smoothly undergo 1,2-addition, acylation, and Pd-catalyzed cross-coupling with various electrophiles. Especially, the oxidative homocoupling of organomanganese reagents was completed in one pot without an additional transition-metal catalyst.
- Peng, Zhihua,Li, Na,Sun, Xinyang,Wang, Fang,Xu, Lanjian,Jiang, Cuiyu,Song, Linhua,Yan, Zi-Feng
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p. 7800 - 7809
(2014/12/10)
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- Fe3O4 nanoparticle-supported Cu(ii)-β- cyclodextrin complex as a magnetically recoverable and reusable catalyst for the synthesis of symmetrical biaryls and 1,2,3-triazoles from aryl boronic acids
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We report here on the preparation of an efficient, easily recoverable and reusable Fe3O4 magnetic nanoparticle-supported Cu(ii)-β-cyclodextrin complex catalyst for the synthesis of symmetrical biaryls and 1,2,3-triazoles from arylboronic acids. The presented Fe 3O4 magnetic nanoparticle-supported Cu(ii)-β- cyclodextrin complex catalyst was characterized by TEM, XRD, VSM, TGA, and FT-IR spectrometer. By using the catalyst, we have developed an efficient protocol for the homocoupling of aryl boronic acids for the synthesis of biaryls. The catalyst is also active in the synthesis of 1,2,3-triazoles via a one-pot reaction of an arylboronic acid with sodium azide in water followed by a click cyclization reaction with an alkyne at room temperature in air without any additives. The reusability of the prepared nanocatalyst was successfully examined four times with only a very slight loss of catalytic activity.
- Kaboudin, Babak,Mostafalu, Ramin,Yokomatsu, Tsutomu
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p. 2266 - 2274
(2013/09/24)
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- CuSO4-mediated homocoupling of arylboronic acids under ligand- and base-free conditions in air
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The homocoupling of arylboronic acids mediated by very inexpensive and air stable copper(II) sulfate in N,N-dimethylformamide affords the corresponding symmetrical biaryls in moderate to good yields. The homocoupling reaction proceeds in air at 50 C in the presence of molecular sieves without any additives such as base and ligand. Georg Thieme Verlag Stuttgart · New York.
- Kaboudin, Babak,Haruki, Terumitsu,Yokomatsu, Tsutomu
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experimental part
p. 91 - 96
(2011/02/28)
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- Ethanol-promoted reductive homocoupling reactions of aryl halides catalyzed by palladium on carbon (Pd/C)
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Homocoupling reactions of aryl bromides or iodides proceeded smoothlywith palladium on carbon (Pd/C) catalyst, ethanol and base in dimethyl sulfoxide (DMSO) to afford exclusively symmetric biaryls in good to excellent yields. Ethanol was first used as a reducing agent in situ to reduce the Pd 2+/C species into Pd0/C active species to complete the catalytic redox cycle. It was found that ethanol can promote the Pd/C-catalyzed reductive homocoupling of aryl iodides and bromides efficiently in the presence of base. A reaction mechanism has been put forward and discussed. Copyright
- Shao, Linjun,Du, Yijun,Zeng, Minfeng,Li, Xiudong,Shen, Wenting,Zuo, Shufeng,Lu, Yueqing,Zhang, Xian-Man,Qi, Chenze
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experimental part
p. 421 - 425
(2010/08/06)
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- Decarboxylative homocoupling of (hetero)aromatic carboxylic acids
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A variety of hetero(aromatic) carboxylic acids are shown to undergo decarboxylative homocoupling, mediated by a Pd/Ag system. This novel methodology for the synthesis of symmetrical biaryls avoids the use of haloarenes and organometallic compounds as starting materials.
- Cornella, Josep,Lahlali, Hicham,Larrosa, Igor
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supporting information; experimental part
p. 8276 - 8278
(2010/12/19)
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- Palladium-catalyzed reductive homocoupling of aromatic halides and oxidation of alcohols
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Palladium-catalyzed reductive homocoupling of aromatic halides can be performed in alcohol solutions without any auxiliary reducing reagents. Pd(dppf)Cl2 [dppf = 1,1′-bis(diphenylphosphino)ferrocene] has been shown as the most effective catalyst among the palladium catalysts screened for the model reductive homocoupling of iodobenzene in alcoholic solutions. The reduction of iodobenzene is stoichiometrically coupled with the oxidation of solvent alcohol (3-pentanol). The X-ray photoelectron spectroscopic (XPS) studies clearly indicate that the oxidation of solvent alcohol molecules is involved with the in situ regeneration of the reductive Pd0(dppf) active species, indicating that the solvent alcohol also reacts as a reducing reagent for the reductive homocoupling of aromatic halides. Elimination of the external reducing reagents will simplify the product separation and purification. Base is essential for the success of the Pd(dppf)Cl 2-catalyzed redox reaction as 2 molar equiv of base is needed to neutralize the acid byproduct formed. Biaryls are the predominant products for the Pd(dppf)Cl2-catalyzed reductions of the unsubstituted aromatic halides in 3-pentanol solution, whereas the dehalogenation products are predominant for the Pd(dppf)Cl2-catalyzed reductions of the substituted aromatic halides. The reaction mechanisms have been discussed for the palladium-mediated concomitant reduction of aromatic halides and oxidation of alcohols without any auxiliary reductants and oxidants.
- Zeng, Minfeng,Du, Yijun,Shao, Linjun,Qi, Chenze,Zhang, Xian-Man
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experimental part
p. 2556 - 2563
(2010/09/11)
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- Palladium catalyzed reductive homocoupling reactions of aromatic halides in dimethyl sulfoxide (DMSO) solution
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Biaryls were obtained in good to excellent yields from the palladium catalyzed reductive homocoupling reactions of various aryl iodides and bromides in dimethyl sulfoxide (DMSO) solution without the need for any additional reducing reagents. Pd(dppf)Cl2 is the most effective among the screened palladium catalysts for the homocoupling reactions. Fluorides, carbonates, acetates and hydroxides can be used as bases at promoting the palladium catalyzed reductive homocoupling of aryl halides in DMSO solution. X-ray photoelectron spectroscopic (XPS) analysis shows that the oxidative Pd2+(dppf) species can be reduced into the Pd0(dppf) active species by solvent DMSO molecules to furnish the catalytic cycle, indicating that DMSO plays a dual role as both solvent and reducing reagent. A plausible reaction mechanism has been discussed. Elimination of additional reducing reagents will not only reduce the reaction operation cost, but will also simplify the product separation and purification.
- Qi, Chenze,Sun, Xudong,Lu, Cuiyun,Yang, Jinzhi,Du, Yijun,Wu, Huajiang,Zhang, Xian-Man
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experimental part
p. 2912 - 2916
(2009/10/23)
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- An efficient high yielding approach for the homocoupling of aryl boronic acids
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A concise, mild, and high yielding method yielding C2-symmetric biaryls is described. The addition of Cu(II) nitrate enhances the rate and the yield of the desired biaryl products. The conditions employed have yielded a number of substituted symmetric biaryls including 1,1′ and 2,2′ BINAP and are useful for the producing symmetric biaryls from their corresponding aryl boronic acids.
- Koza, Darrell J.,Carita, Eric
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p. 2183 - 2186
(2007/10/03)
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- Catalysis by nickel-2,2'-dipyridylamine complexes of the electroreductive coupling of aromatic halides in ethanol
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Nickel-2,2'-dipyridylamine complexes are efficient catalysts for achieving in pure ethanol electroreductive dimerisation of aromatic halides or arylation of activated olefins.
- Courtois, Valerie,Barhdadi, Rachid,Condon, Sylvie,Troupel, Michel
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p. 5993 - 5996
(2007/10/03)
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- Activation of Reducing Agents. Sodium Hydride Containing Complex Reducing Agents. 31. NiCRAL's as Very Efficient Agents in Promoting Homo-Coupling of Aryl Halides
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Homo-coupling of aryl bromides and chlorides is efficiently performed with nickel-containing complex reducing agents NiCRA-bpy.In a number of cases the presence of alkali iodides improves the procedure.Yields are very high and a number of functional groups are resistant.The mechanistic and catalytic aspect of these reactions are discussed.
- Lourak, Mouhsine,Vanderesse, Regis,Fort, Yves,Caubere, Paul
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p. 4840 - 4844
(2007/10/02)
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- Activation of Reducing Agents. Sodium Hydride Containing Complex Reducing Agents. 32. NiCRAL's as Very Efficient Agents in Promoting Cross-Coupling of Aryl Halides
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Nickel-containing complex reducing agents NiCRA-bpy are shown to be the first nickel reagents able to efficiently perform cross-coupling of aryl halides.The presence of KI in the reaction medium generally improves the procedure.The mechanism and influence of the structures of the substrates are discused.
- Lourak, Mouhsine,Vanderesse, Regis,Fort, Yves,Caubere, Paul
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p. 4844 - 4848
(2007/10/02)
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- A zerovalent nickel-2,2'-bipyridine complex: an efficient catalyst for electrochemical homocoupling of ortho-substituted halides and their heterocoupling with meta- and para-substituted halides
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Electroreduction of ortho-substituted halides Ar-X in a nickel-2,2'-bipyridyl system and N-methylpyrrolidone as solvent gave the homocoupling product ArAr.The nickel-2,2'-bipyridyl system is also a catalyst for the electrochemical heterocoupling of ArX with meta- or para-substituted halides Ar'X'.
- Meyer, Gilbert,Rollin, Yolande,Perichon, Jacques
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p. 263 - 268
(2007/10/02)
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- PALLADIUM(II)-CATALYZED OXIDATIVE COUPLING OF ARENES BY THALLIUM(III)
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Oxidation of benzenes with electron-donating and moderate electron-withdrawing substituents by thallium(III) trifluoroacetate in the presence of catalytic amounts of palladium(II) acetate affords biaryls in good yields.The GLC study of the isomer distribution has shown that 4,4'-biaryls are the major products.Thus, the 4,4'-biaryls can be easily isolated either by recrystallization or column chromatography.The competitive experiments and kinetic study using arenes and arylthallium derivatives as starting materials as well as quenching experiments have demonstrated the first step of the reaction to be fast thallation of arene to form arylthallium intermediate ArTl(OOCCF3)2.The latter undergoes the rate-determining transmetallation step reacting with monomeric complex Pd(OAc)2, which is formed upon depolymerization of trimer Pd3(OAc)6.Subsequent fast decomposition of arylpalladium species gives the final reaction products.The thallation of arene and substitution of TlIII for PdII in ArTl(OOCCF3)2 are characterized by the slopes of Hammet plots of -5.6 (?+) and -3.0 (?), respectively.
- Yatsimirsky, Anatoly K.,Deiko, Sergei A.,Ryabov, Alexander D.
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p. 2381 - 2392
(2007/10/02)
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