- meta-Selective C?H Arylation of Fluoroarenes and Simple Arenes
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Fluorine is known to promote ortho-C?H metalation. Based upon this reactivity, we employed an activated norbornene that traps the ortho-palladation intermediate and is then relayed to the meta position, leading to meta-selective C?H arylation of fluoroarenes. Deuterium experiment suggests that this meta-arylation is initiated by ortho C?H activation and the catalytic cycle is terminated by C-2 protonation. A dual-ligand system is crucial for the observed high reactivity and site selectivity. Applying this approach to simple benzene or other arenes also affords arylation products with good yield and site selectivity.
- Liu, Luo-Yan,Qiao, Jennifer X.,Yeung, Kap-Sun,Ewing, William R.,Yu, Jin-Quan
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- NiIICl(1-Naphthyl)(PCy3)2, An Air-Stable σ-NiII Precatalyst for Quantitative Cross-Coupling of Aryl C-O Electrophiles with Aryl Neopentylglycolboronates
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Advances in nickel catalysis have enabled the employment of the widely available and environmentally benign phenol derivatives as aryl electrophiles in Suzuki-Miyaura cross-coupling reactions. NiII-phosphine complexes such as NiIICl
- Malineni, Jagadeesh,Jezorek, Ryan L.,Zhang, Na,Percec, Virgil
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- Bathocuproine-Enabled Nickel-Catalyzed Selective Ullmann Cross-Coupling of Two sp 2-Hybridized Organohalides
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Cross-coupling reactions are essential for the synthesis of complex organic molecules. Here, we report a nickel-catalyzed Ullmann cross-coupling of two sp 2-hybridized organohalides, featuring high cross-selectivity when the two coupling partners are used in a 1:1 ratio. The high chemoselectivity is governed by the bathocuproine ligand. Moreover, the mild reductive reaction conditions allow that a wide range of functional groups are compatible in this Ullmann cross-coupling.
- Li, Yuqiang,Yin, Guoyin
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supporting information
p. 1657 - 1661
(2021/09/13)
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- Cobalt-catalyzed C(sp2)?CN bond activation: Cross-electrophile coupling for biaryl formation and mechanistic insight
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Herein, we report a cross-electrophile coupling of benzonitrile derivatives and aryl halides with a simple cobalt-based catalytic system under mild conditions to form biaryl compounds. Even though the cobalt catalyst is able to activate the C(sp2)?CN bond alone, the use of the AlMe3 Lewis acid enhances the reactivity of benzonitriles and improves the cross-selectivity with barely any influence on the functional group compatibility. X-ray structure determination of an original low-valent cobalt species combined with catalytic and stoichiometric reactions reveals a catalytically active cobalt(I) species toward the aryl halide partner. On the other hand, experimental insights, including cyclic voltammetry experiments, suggest the involvement of a cobalt complex of a lower oxidation state to activate the benzonitrile derivative. Finally, density functional theory calculations support the proposed mechanistic cycle involving two low-valent cobalt species of different oxidation states to perform the reaction.
- Dorval, Céline,Tricoire, Maxime,Begouin, Jeanne-Marie,Gandon, Vincent,Gosmini, Corinne
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p. 12819 - 12827
(2020/11/18)
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- Decarbonylative Phosphorylation of Carboxylic Acids via Redox-Neutral Palladium Catalysis
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We describe the direct synthesis of organophosphorus compounds from ubiquitous aryl and vinyl carboxylic acids via decarbonylative palladium catalysis. The catalytic system shows excellent scope and tolerates a wide range of functional groups (>50 examples). The utility of this powerful methodology is highlighted in the late-stage derivatization directly exploiting the presence of the prevalent carboxylic acid functional group. DFT studies provided insight into the origin of high bond activation selectivity and P(O)-H isomerization pathway.
- Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
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supporting information
p. 9256 - 9261
(2019/11/19)
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- Palladacycles derived from arylphosphinamides for mild Suzuki-Miyaura cross-couplings
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We present a type of palladacyclic complexes derived from arylphosphinamides which can be used as efficient and versatile precatalysts for mild Suzuki-Miyaura cross-coupling. With the presence of 1.0 mol% of palladacycles, a wide variety of aryl bromides and boronic acids could be coupled very efficiently at ambient temperature and under air atmosphere without the need of external supporting ligands. Moreover, the mild conditions also allow for smooth coupling of electron-deficient, i.e., the less stable aryl triflates. In addition to the highly catalytic activity, the palladacyclic complexes can be very easily prepared through a two-step procedure from the readily affordable diphenyl-phosphinic chloride and exhibit excellent stability toward air and moisture. Due to these prominent properties, the new palladacycles would find practical use in Suzuki-Miyaura couplings.
- Wu, Guo-Jie,Han, Fu-She,Zhao, Yu-Long
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p. 69776 - 69781
(2015/09/01)
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- Nickel catalyzed cross-coupling of aryl C-O based electrophiles with aryl neopentylglycolboronates
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The efficiency of mesylates, sulfamates, esters, carbonates, carbamates, and methyl ethers as C-O-based electrophiles attached to the 1- or 2-position of naphthalene and to activated and nonactivated phenyl substrates was compared for the first time in Ni-catalyzed cross-coupling with phenyl neopentylglycolboronates containing electron-rich and electron-deficient substituents in their para-position. These experiments were performed in the presence of four different Ni(II)- and Ni(0)-based catalysts. Ni(II)-based catalysts mediate the cross-coupling of most 2-naphthyl C-O electrophiles with both arylboronic acids and with neopentylglycolboronates when K 3PO4 is used as base. The same catalysts are not efficient when CsF is used as base. However, Ni(0)-based catalysts exhibit selective efficiency, and when reactive, their efficiency is higher than that of Ni(II)-based catalysts in the presence of both K3PO4 and CsF. These results provide both reaction conditions for the cross-coupling, and for the elaboration of orthogonal cross-coupling methodologies of various C-O based electrophiles with aryl neopentylglycolboronates. With the exception of mesylates and sulfamates the efficiency of all other 2-naphthyl C-O electrophiles was lower in cross-coupling with aryl neopentylglycolboronates than with arylboronic acids
- Leowanawat, Pawaret,Zhang, Na,Percec, Virgil
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experimental part
p. 1018 - 1025
(2012/03/22)
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- Nickel-catalyzed cross-coupling of aryl phosphates with arylboronic acids
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The Suzuki-Miyaura cross-coupling of aryl phosphates using Ni(PCy 3)2Cl2 as an inexpensive, bench-stable catalyst is described. Broad substrate scope and high efficiency are demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules. The poor reactivity of aryl phosphates relative to aryl halides is successfully employed to construct polyarenes by selective cross-coupling using Pd and Ni catalysts.
- Chen, Hu,Huang, Zhongbin,Hu, Xiaoming,Tang, Guo,Xu, Pengxiang,Zhao, Yufen,Cheng, Chien-Hong
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experimental part
p. 2338 - 2344
(2011/05/30)
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- Nickel-catalyzed cross-coupling of phenols and arylboronic acids through an in situ phenol activation mediated by PyBroP
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A new method for the Suzuki-Miyaura cross-coupling of phenols and arylboronic acids through in situ phenol activation mediated by PyBroP is presented. The reaction proceeds efficiently by using cost-effective, markedly stable [NiCl2(dppp)] (dppp=1,3-bis(diphenylphosphino)propane) as the catalyst in only 5 mol % loading, as well as in the absence of extra ligands. The method exhibits broad applicability and high efficiency towards a wide range of both phenols and boronic acids, including activated, nonactivated, deactivated, and heteroaromatic coupling partners. In addition, various functional groups, such as ether, amino, cyano, ester, and ketone groups, are compatible with this transformation. Notably, arylboronic acids containing an unprotected NH2 group and 2-heterocyclic boronic acids, which are generally problematic for coupling under conventional conditions, are also viable substrates, although moderate yields were obtained for sterically hindered substrates. Consequently, the in situ cross-coupling methodology coupled with the use of an inexpensive and stable nickel catalyst provides a rapid and efficient pathway for the assembly of biaryls and heterobiaryls with structural diversity from readily available phenol compounds.
- Chen, Guo-Jun,Huang, Jie,Gao, Lian-Xun,Han, Fu-She
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supporting information; experimental part
p. 4038 - 4042
(2011/05/05)
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- Nickel-catalyzed cross-coupling of aryl methyl ethers with aryl boronic esters
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(Chemical Equation Presented) To C-OMe and go: The title reaction, involving cleavage of a C-OMe bond, is demonstrated for the coupling of aryl methyl ethers on fused aromatic systems, such as naphthalene and phenanthrene, as well as anisoles containing electron-withdrawing groups with a wide range of boronic esters. cod=cycloocta-1,5-diene, Cy=cyclohexyl.
- Tobisu, Mamoru,Shimasaki, Toshiaki,Chatani, Naoto
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experimental part
p. 4866 - 4869
(2009/02/08)
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- Use of functionalized onium salts as a soluble support for organic synthesis
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The invention relates to the use of a onium salt functionalized by at least one organic function, as a soluble support, in the presence of at least one organic solvent, for organic synthesis of a molecule, in a homogenous phase, by at least one transformation of said organic function. The onium salt enables the synthesized molecule to be released. The onium salt is present in liquid or solid form at room temperature and corresponds to formula A1+, X1?, wherein A1+ represents a cation and X1? represents an anion.
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Page/Page column 51
(2010/11/25)
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- Poly(ethylene glycol) supported liquid phase synthesis of biaryls
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The liquid phase synthesis of biaiyls via Suzuki cross-coupling reaction on polyethylene glycol) supports (PEGs) is described. The reaction is exemplified by parallel coupling of polymer bound aryl halides with boronic acids. Four different PEGs were employed as soluble polymer supports for parallel synthesis. The generated libraries include both sterically hindered aryl halides (2b, 2d) and boronic acids. The reactions were run in the homogeneous phase and the synthetic sequences performed in parallel fashion. Quantitative conversion in the Suzuki couplings was verified by 1H-NMR analysis (3a-r). The polymer bound products were isolated in good to excellent (52% to 98%) yields by either simple precipitation of the soluble support or column filtration.
- Blettner, Carsten G.,K?nig, Wilfried A.,Stenzel, Wolfgang,Schotten, Theo
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p. 295 - 297
(2007/10/03)
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