- Synthesis and optical resolution of a double helicate consisting of ortho-linked hexaphenol strands bridged by spiroborates
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(Figure Presented) Double Twist: The first spiroborate-based helicate was synthesized and shown to be stable in the solid state as well as in solution. The double-stranded structure (see picture) was characterized by 1H NMR spectroscopy, ESI MS
- Katagiri, Hiroshi,Miyagawa, Toyoharu,Furusho, Yoshio,Yashima, Eiji
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Read Online
- Functionalized organocuprates: Structures of lithium and magnesium grignard 2-methoxyphenylcuprates
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Lithium and magnesium Grignard diorganocuprates incorporating the functionalized aryl group 2-methoxyphenyl have been prepared and structurally characterized in the solid state. [Cu4Li2(C 6H4OMe-2)6(T
- Bomparola, Roberta,Davies, Robert P.,Lal, Steven,White, Andrew J. P.
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Read Online
- 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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- Pd-catalyzed oxidative homocoupling of arylboronic acids in WEPA: A sustainable access to symmetrical biaryls under added base and ligand-free ambient conditions
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Symmetrical and unsymmetrical biaryls comprises a diverse class of biologically eloquent organic compounds. We herein report, a quick and eco-friendly protocol for the synthesis of biaryls by an oxidative (aerobic) homocoupling of arylboronic acids (ABAs) using Pd(OAc)2 in water extract of pomogranate ash (WEPA) as an efficient agro-waste(bio)-derived aqueous (basic) media. The reactions were executed at ambient aerobic conditions in the absence of external base and ligand to result symmetrical biaryls in excellent yields. The use of renewable media with an effective exploitation of waste, short reaction times, excellent yields of products, easy separation of the products, unnecessating the external base, oxidant, ligand or volatile organic solvents and ambient reaction conditions are the vital insights of the present protocol.
- Appa, Rama Moorthy,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Venkateswarlu, Katta
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- Identification of a Surprising Boronic Acid Homocoupling Process in Suzuki-Miyaura Cross-Coupling Reactions Utilizing a Hindered Fluorinated Arene
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The Suzuki-Miyaura cross-coupling reaction of 2-bromo-1,3-bis(trifluoromethyl)benzene with arylboronic acids was evaluated and determined to suffer from the formation of large amounts of boronic acid homocoupling products in conjunction with dehalogenation. Homocoupling product formation in this process likely occurs through a rare protonolysis/second transmetalation event rather than by the well-established mechanism requiring the involvement of O 2. The scope of this boronic acid homocoupling reaction was investigated and shown to predominate with electron-deficient arylboronic acids. Finally, a good yield of cross-coupling products could be obtained by employing dicyclohexyl(2′,6′-dimethoxybiphenyl-2-yl)phosphine (SPhos) as the ligand.
- Gargaro, Samantha L.,Dunson, Bre'Shon,Sieber, Joshua D.
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supporting information
p. 511 - 516
(2020/09/21)
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- Sustainable Synthesis of Biaryls Using Silica Supported Ferrocene Appended N-Heterocyclic Carbene-Palladium Complex
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Abstract: A novel silica supported ferrocene appended N-heterocyclic carbene-palladium complex (SilFemBenzNHC@Pd) has been prepared and characterized by using fourier transform infrared (FT-IR), fourier transform Raman (FT-Raman), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and energy dispersive X-ray analysis (EDX). This novel complex served as a robust heterogeneous catalyst for the synthesis of biaryls via homocoupling of aryl boronic acids under base-free conditions in water. Recyclability experiments were executed successfully for six successive runs. Graphic Abstract: [Figure not available: see fulltext.]
- Khanapure, Sharanabasappa,Pore, Dattaprasad,Jagadale, Megha,Patil, Vaishali,Rashinkar, Gajanan
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p. 2237 - 2249
(2021/01/11)
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- Tandem Mn–I Exchange and Homocoupling Processes Mediated by a Synergistically Operative Lithium Manganate
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Pairing lithium and manganese(II) to form lithium manganate [Li2Mn(CH2SiMe3)4] enables the efficient direct Mn–I exchange of aryliodides, affording transient (aryl)lithium manganate intermediates which in turn undergo spontaneous C?C homocoupling at room temperature to furnish symmetrical (bis)aryls in good yields under mild reaction conditions. The combination of EPR with X-ray crystallographic studies has revealed the mixed Li/Mn constitution of the organometallic intermediates involved in these reactions, including the homocoupling step which had previously been thought to occur via a single-metal Mn aryl species. These studies show Li and Mn working together in a synergistic manner to facilitate both the Mn–I exchange and the C?C bond-forming steps. Both steps are carefully synchronized, with the concomitant generation of the alkyliodide ICH2SiMe3 during the Mn–I exchange being essential to the aryl homocoupling process, wherein it serves as an in situ generated oxidant.
- Uzelac, Marina,Mastropierro, Pasquale,de Tullio, Marco,Borilovic, Ivana,Tarrés, Màrius,Kennedy, Alan R.,Aromí, Guillem,Hevia, Eva
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supporting information
p. 3247 - 3253
(2020/12/11)
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- Tunable and Practical Homogeneous Organic Reductants for Cross-Electrophile Coupling
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The syntheses of four new tunable homogeneous organic reductants based on a tetraaminoethylene scaffold are reported. The new reductants have enhanced air stability compared to current homogeneous reductants for metal-mediated reductive transformations, such as cross-electrophile coupling (XEC), and are solids at room temperature. In particular, the weakest reductant is indefinitely stable in air and has a reduction potential of -0.85 V versus ferrocene, which is significantly milder than conventional reductants used in XEC. All of the new reductants can facilitate C(sp2)-C(sp3) Ni-catalyzed XEC reactions and are compatible with complex substrates that are relevant to medicinal chemistry. The reductants span a range of nearly 0.5 V in reduction potential, which allows for control over the rate of electron transfer events in XEC. Specifically, we report a new strategy for controlled alkyl radical generation in Ni-catalyzed C(sp2)-C(sp3) XEC. The key to our approach is to tune the rate of alkyl radical generation from Katritzky salts, which liberate alkyl radicals upon single electron reduction, by varying the redox potentials of the reductant and Katritzky salt utilized in catalysis. Using our method, we perform XEC reactions between benzylic Katritzky salts and aryl halides. The method tolerates a variety of functional groups, some of which are particularly challenging for most XEC transformations. Overall, we expect that our new reductants will both replace conventional homogeneous reductants in current reductive transformations due to their stability and relatively facile synthesis and lead to the development of novel synthetic methods due to their tunability.
- Barth, Emily L.,Charboneau, David J.,Germe, Cameron C.,Hazari, Nilay,Huang, Haotian,Mercado, Brandon Q.,Uehling, Mycah R.,Zultanski, Susan L.
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supporting information
p. 21024 - 21036
(2021/12/14)
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- Highly Active Fe3O4@SBA-15@NHC-Pd Catalyst for Suzuki–Miyaura Cross-Coupling Reaction
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A novel Pd-NHC functionalized magnetic Fe3O4@SBA-15@NHC-Pd was synthesized and used as an efficient heterogeneous catalyst in the Suzuki–Miyaura C–C bond formation reactions. The Fe3O4@SBA-15@NHC-Pd characterized by X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy?(TEM), Energy Dispersive X-ray analysis (EDX), Thermogravimetric Analysis (TGA), Differential Thermal Analysis (DTA). The Inductively Coupled Plasma-Optical emission spectroscopy (ICP-OES)?analysis was used to determine the exact amount of Pd (0.33?wt%) in Fe3O4@SBA-15@NHC-Pd. The TEM images of the catalyst showed the existence of palladium nanoparticles immobilized in the catalyst's structure, while no reducing agent was used. The NHC moieties in the catalyst structure could be stabilize Pd(0) nanoparticles prevents agglomeration. The magnetic catalyst was effectively used in the Suzuki–Miyaura cross-coupling reaction of substituted phenylboronic acid derivatives with (hetero)aryl bromides in the presence of a K2CO3 at room temperature in aqueous media and magnetic catalyst could be simply extracted from the reaction mixture by an external magnet. Different aryl bromides were converted to coupled-products in excellent yields with spectacular TOFs values (up to 1,960,339?h?1); in the presence of 1?mg of Fe3O4@SBA-15@NHC-Pd catalyst (contains 3.1 × 10–6?mol% Pd) at room temperature in aqueous media. After reusability experiments, it is found that this catalyst was effectively used up to ten times in the reaction with almost consistent catalytic efficiency. A decrease in the activity of the 10th reused catalyst was found as 9%. Graphic Abstract: [Figure not available: see fulltext.]
- ?zdemir, ?smail,Akko?, Mitat,Alt?n, Serdar,Bu?day, Nesrin,Ya?ar, Sedat
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- Pd-catalyzed cross-electrophile Coupling/C-H alkylation reaction enabled by a mediator generatedviaC(sp3)-H activation
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Transition-metal-catalyzed cross-electrophile C(sp2)-(sp3) coupling and C-H alkylation reactions represent two efficient methods for the incorporation of an alkyl group into aromatic rings. Herein, we report a Pd-catalyzed cascade cross-electrophile coupling and C-H alkylation reaction of 2-iodo-alkoxylarenes with alkyl chlorides. Methoxy and benzyloxy groups, which are ubiquitous functional groups and common protecting groups, were utilized as crucial mediatorsviaprimary or secondary C(sp3)-H activation. The reaction provides an innovative and convenient access for the synthesis of alkylated phenol derivatives, which are widely found in bioactive compounds and organic functional materials.
- Jiang, Hang,Wu, Zhuo,Zhang, Yanghui
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p. 8531 - 8536
(2021/07/02)
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- Porphyrin n-pincer pd(Ii)-complexes in water: A base-free and nature-inspired protocol for the oxidative self-coupling of potassium aryltrifluoroborates in open-air
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Metalloporphyrins (and porphyrins) are well known as pigments of life in nature, since representatives of this group include chlorophylls (Mg-porphyrins) and heme (Fe-porphyrins). Hence, the construction of chemistry based on these substances can be based on the imitation of biological systems. Inspired by nature, in this article we present the preparation of five different porphyrin, meso-tetraphenylporphyrin (TPP), meso-tetra(p-anisyl)porphyrin (TpAP), tetra-sodium meso-tetra(p-sulfonatophenyl)porphyrin (TSTpSPP), meso-tetra(m-hydroxyphenyl)porphyrin (TmHPP), and meso-tetra(m-carboxyphenyl)porphyrin (TmCPP) as well as their N-pincer Pd(II)-complexes such as Pd(II)-meso-tetraphenylporphyrin (PdTPP), Pd(II)-meso-tetra(p-anisyl)porphyrin (PdTpAP), Pd(II)-tetrasodium meso-tetra(p-sulfonatophenyl)porphyrin (PdTSTpSPP), Pd(II)-meso-tetra(m-hydroxyphenyl)porphyrin (PdTmHPP), and Pd(II)-meso-tetra(m-carboxyphenyl)porphyrin (PdTmCPP). These porphyrin N-pincer Pd(II)-complexes were studied and found to be effective in the base-free self-coupling reactions of potassium aryltrifluoroborates (PATFBs) in water at ambient conditions. The catalysts and the products (symmetrical biaryls) were characterized using their spectral data. The high yields of the biaryls, the bio-mimicking conditions, good substrate feasibility, evading the use of base, easy preparation and handling of catalysts, and the application of aqueous media, all make this protocol very attractive from a sustainability and cost-effective standpoint.
- Prasad, Sana Siva,Naidu, Bandameeda Ramesh,Hanafiah, Marlia M.,Lakshmidevi, Jangam,Marella, Ravi Kumar,Lakkaboyana, Sivarama Krishna,Venkateswarlu, Katta
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- A Bio-Inspired Magnetically Recoverable Palladium Nanocatalyst for the Ullmann Coupling reaction of Aryl halides and Arylboronic acids In Aqueous Media
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Palladium nanoparticles supported on polydopamine-coated iron oxide nanoparticles (Pd/Fe3O4@PDA) were found to catalyze the Ullmann homocoupling of a wide variety of aryl halides, arylboronic acids and aryldiazonium salts in aqueous media in the presence of randomly methylated β-cyclodextrin (RM-β-CD). The synthesized nanoparticles were characterized by techniques such as TEM, SEM, EDX, XPS, ICP-AES and XRD. The synthesized catalyst can be easily recovered magnetically and reused up to five cycles without any significant loss of activity. This is the first report demonstrating the use of magnetically recoverable catalyst for Ullmann homocoupling reactions of aryl halides, arylboronic acids and aryldiazonium salts in water.
- Dubey, Abhishek V.,Kumar, A. Vijay
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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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- Aerobic and Ligand-Free Manganese-Catalyzed Homocoupling of Arenes or Aryl Halides via in Situ Formation of Aryllithiums
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Ligand-free manganese-catalyzed homocoupling of arenes or aryl halides can be carried out under aerobic conditions via the in situ formation of the corresponding aryllithiums. A wide range of biaryls and derivatives has been obtained, and a mechanism involving monomeric manganese-oxo complexes has been proposed on the basis of DFT calculations.
- Liu, Yujia,Bergès, Julien,Zaid, Yassir,Chahdi, Fouad Ouazzani,Van Der Lee, Arie,Harakat, Dominique,Clot, Eric,Jaroschik, Florian,Taillefer, Marc
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p. 4413 - 4420
(2019/03/26)
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- PdAu alloy nanoparticles supported on nitrogen-doped carbon black as highly active catalysts for Ullmann coupling and nitrophenol hydrogenation reactions
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Noble metal-based catalysts have been proven to be active for catalytic organic reactions. The selectivity and conversion can be improved by integration with proper carrier materials, and further modulated by tuning the composition as well as the electronic structure of the active noble metals. Compared with unsupported monometallic catalysts, the synergistic interactions between neighboring metals and the combined effects between the carrier materials and the active components often give rise to positive influences on the enhancement of the catalytic efficiency and selectivity. In this work, we report a facile process for the fabrication of nitrogen-doped carbon black (NCB) supported PdAu bimetallic nanoparticles (NPs) with a uniform dispersion and narrow size distribution. The PdAu/NCB catalyst with a Pd/Au mole ratio of 1/1 shows the highest activity towards both Ullmann coupling reactions of aryl halides and the hydrogenation reaction of nitrophenols. Moreover, this bimetallic catalyst also exhibits a superior recycling durability to that of monometallic Pd/NCB and Au/NCB catalysts. The enhanced catalytic performance of the bimetallic catalyst is mainly due to the large BET specific surface area (125.45 m2 g-1) and the synergy between the individual components of the catalyst.
- Han, Fengyan,Xia, Jiawei,Zhang, Xinglong,Fu, Yongsheng
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p. 17812 - 17823
(2019/06/24)
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- Probing the Existence of a Metastable Binding Site at the β2-Adrenergic Receptor with Homobivalent Bitopic Ligands
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Herein, we report the development of bitopic ligands aimed at targeting the orthosteric binding site (OBS) and a metastable binding site (MBS) within the same receptor unit. Previous molecular dynamics studies on ligand binding to the β2-adrenergic receptor (β2AR) suggested that ligands pause at transient, less-conserved MBSs. We envisioned that MBSs can be regarded as allosteric binding sites and targeted by homobivalent bitopic ligands linking two identical pharmacophores. Such ligands were designed based on docking of the antagonist (S)-alprenolol into the OBS and an MBS and synthesized. Pharmacological characterization revealed ligands with similar potency and affinity, slightly increased β2/β1AR-selectivity, and/or substantially slower β2AR off-rates compared to (S)-alprenolol. Truncated bitopic ligands suggested the major contribution of the metastable pharmacophore to be a hydrophobic interaction with the β2AR, while the linkers alone decreased the potency of the orthosteric fragment. Altogether, the study underlines the potential of targeting MBSs for improving the pharmacological profiles of ligands.
- Gaiser, Birgit I.,Danielsen, Mia,Marcher-R?rsted, Emil,R?pke J?rgensen, Kira,Wróbel, Tomasz M.,Frykman, Mikael,Johansson, Henrik,Br?uner-Osborne, Hans,Gloriam, David E.,Mathiesen, Jesper Mosolff,Sejer Pedersen, Daniel
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p. 7806 - 7839
(2019/09/07)
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- Room-temperature borylation and one-pot two-step borylation/Suzuki-Miyaura cross-coupling reaction of aryl chlorides
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A highly efficient room-temperature borylation strategy of aryl chlorides is described. Utilizing Buchwald's second-generation preformed catalyst, boronate esters were obtained for a wide range of substrates in high yield. The method was also applied to Suzuki-Miyaura cross-coupling reaction in a one-pot two-step sequential manner, providing a facile and convenient access to the direct synthesis of biaryl compounds from aryl chlorides.
- Ji, Hong,Wu, Li-Yang,Cai, Jiang-Hong,Li, Guo-Rong,Gan, Na-Na,Wang, Zhao-Hua
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p. 13643 - 13648
(2018/04/24)
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- WEPA: a bio-derived medium for added base, π-acid and ligand free Ullmann coupling of aryl halides using Pd(OAc)2
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A bio-derived sustainable medium based on water extract of pomegranate ash (WEPA) has, for the first time, been developed for the homocoupling of aryl halides under palladium-assistance. Avoiding the requirement of an external base, ligand and π-acid, the use of the proposed renewable medium offers remarkable attributes like wide substrate scope, good to nearly quantitative yields of biphenyls with exceptional chemoselectivity and scale up viability.
- Lakshmidevi, Jangam,Appa, Rama Moorthy,Naidu, Bandameeda Ramesh,Prasad, S. Siva,Sarma, Loka Subramanyam,Venkateswarlu, Katta
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supporting information
p. 12333 - 12336
(2018/11/30)
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- One-pot two-step stannylation/Stille homocoupling of aryl bromides and iodides under solvent-free conditions
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A new highly efficient solvent-free method for aryl bromide (iodide) homocoupling comprising the use of Pd(OAc)2/PCy3 system in the presence of CsF is suitable for substrates bearing functional groups not tolerant to lithium-, magnesium-, zincorganic reagents and strong bases.
- Gribanov, Pavel S.,Golenko, Yulia D.,Topchiy, Maxim A.,Philippova, Anna N.,Kirilenko, Nikita Yu.,Krivoshchapov, Nikolai V.,Sterligov, Grigorii K.,Asachenko, Andrey F.,Bermeshev, Maxim V.,Nechaev, Mikhail S.
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p. 323 - 325
(2018/05/30)
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- Fast, Efficient and Low E-Factor One-Pot Palladium-Catalyzed Cross-Coupling of (Hetero)Arenes
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The homocoupling of aryl halides and the heterocoupling of aryl halides with either aryl bromides or arenes bearing an ortho-lithiation directing group are presented. The use of a Pd catalyst, in combination with t-BuLi, allows for the rapid and efficient formation of a wide range of polyaromatic compounds in a one pot procedure bypassing the need for the separate preformation of an organometallic coupling partner. These polyaromatic structures are obtained in high yields, in 10 min at room temperature, with minimal waste generation (E-factors as low as 1.5) and without the need for strict inert conditions, making this process highly efficient and practical in comparison to classical methods. As illustration, several key intermediates of widely used BINOL-derived structures are readily prepared.
- Pinxterhuis, Erik B.,Visser, Paco,Esser, Iwan,Gualtierotti, Jean-Baptiste,Feringa, Ben L.
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supporting information
p. 9452 - 9455
(2017/10/23)
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- Dimerization of Aromatic Compounds Using Palladium-Carbon-Catalyzed Suzuki-Miyaura Cross-Coupling by One-Pot Synthesis
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The aromatic dimers play a significant role in many aspects. Herein, we report a simple palladium-carbon catalyst that is highly effective for the dimerization of brominated aromatic compounds under mild conditions using abundant brominated aromatic compounds, bis(pinacolate)diboron and potassium acetate by a 'one-pot' method. This process, which we believe proceeds via a Suzuki-Miyaura cross-coupling reaction mechanism, allows access to a variety of aromatic compounds under mild reaction conditions and has a good functional group tolerance with moderate to high yields.
- Du, Fangyu,Zhou, Qifan,Liu, Dongdong,Fang, Ting,Shi, Yajie,Du, Yang,Chen, Guoliang
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supporting information
p. 779 - 784
(2018/02/09)
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- Nickel-Catalyzed Electrochemical Reductive Homocouplings of Aryl and Heteroaryl Halides: A Useful Route to Symmetrical Biaryls
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Due to their widespread presence in functional materials and pharmaceuticals, biaryls are of fundamental importance in organic chemistry. Methods for the synthesis of symmetrical biaryls generally involve both metallic reduction and transition-metal catalysis. In this work, we show that electroreduction can also constitute a very relevant way to achieve the nickel-catalyzed reductive synthesis of symmetrical biaryl compounds. Therefore, it is demonstrated that both aryl and heteroaryl halides undergo reductive coupling to furnish the corresponding symmetrical biaryls in fair to excellent yields. Reactions are performed under very mild conditions thus ensuring important functional group tolerance.
- Rahil, Rima,Sengmany, Stéphane,Le Gall, Erwan,Léonel, Eric
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p. 146 - 154
(2017/09/28)
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- A Copper-Catalyzed Reductive Defluorination of β-Trifluoromethylated Enones via Oxidative Homocoupling of Grignard Reagents
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An efficient copper-catalyzed reductive defluorination of β-trifluoromethylated enones via an oxidative homocoupling of Grignard reagents is reported. The reaction proceeded smoothly with a wide range of substrates, including the ones bearing aromatic heterocycles, such as furyl and thienyl ring systems in high yields (80-92%, except one example) under mild conditions. This provides a practical method for synthesis of gem-difluoroolefin ketones. It is also worth noting that this homocoupling process of Grignard reagents using β-trifluoromethylated enones as oxidizing reagents is effective for both the Csp2-Csp2 and Csp3-Csp3 bond formations, including for substrates whose β-hydride elimination of the corresponding transition metal alkyl complex is particularly facile, affording coupling products with high yields (83-95%), simultaneously.
- Wu, Xiaoting,Xie, Fang,Gridnev, Ilya D.,Zhang, Wanbin
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p. 1638 - 1642
(2018/03/23)
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- Synthesis, characterization and crystal structure of Cu(II) complex of trans-cyclohexane-1,2-diamine: Application in synthesis of symmetrical biaryls
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A new Cu(II) complex [Cu(cyhxn)2(H2O)2][OTf]2 was synthesised by the reaction of ligand cyhxn (cyhxn?=?trans-cyclohexane-1,2-diamine) with Cu(OTf)2 in methanol at room temperature. The complex was fully characterized by elemental analysis (CHN), FT-IR, UV–Vis and EPR spectroscopic techniques. The structure of the complex was confirmed by single crystal X-ray diffraction study. The EPR spectrum is isotropic type having giso?=?2.078, which indicates a distorted octahedral geometry of the complex. The complex was found to be an active homogeneous catalyst for the homocoupling reactions of arylboronic acid to obtain symmetrical biaryls at room temperature in methanol without the use of any additives such as a base and or an oxidant.
- Agrahari, Bhumika,Layek, Samaresh,Kumari, Shweta,Anuradha,Ganguly, Rakesh,Pathak, Devendra D.
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- Carbon-carbon bond forming reactions via Pd-catalyzed detellurative homocoupling of diorganyl tellurides
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A simple and highly efficient method for the constructions of Csp-Csp, Csp2-Csp2 and Csp3-Csp3 bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl2 as a catalyst in the presence of Ag2O and Na2CO3. Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively.
- Zhang, Shaozhong,Kolluru, Lalitha,Vedula, Souseelya K.,Whippie, Drew,Jin, Jin
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p. 3594 - 3597
(2017/08/23)
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- Bimetallic Au-Pd nanochain networks: Facile synthesis and promising application in biaryl synthesis
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A simple and facile method is described for the morphology-controlled synthesis of bimetallic Au-Pd alloyed nanochain networks (NNCs) that show high catalytic performance for the Ullmann intermolecular homocoupling of aromatic or alkyl halides (X = I, Br, Cl) in aqueous media and can be reused at least five times, which can also be applied to intramolecular homocoupling.
- Wang, Zheng-Jun,Wang, Xia,Lv, Jing-Jing,Feng, Jiu-Ju,Xu, Xinhua,Wang, Ai-Jun,Liang, Zhiwu
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p. 3894 - 3899
(2017/07/12)
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- Copper-free palladium-catalysed desulfinative homocoupling of sodium arylsulfinates under mild and aerobic conditions
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A Pd(II)-catalysed homocoupling of sodium arylsulfinates has been successfully achieved under mild conditions. This transformation is a new method for the homocoupling reaction of sodium arylsulfinates, thus providing an alternative synthesis of symmetric biaryls. The reported homocoupling reaction is tolerant to many common functional groups, such as ester, halo, cyano and nitro and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported desulfinative homocoupling does not require Cu salts, ligands and bases, making this newly developed transformation attractive.
- Zhang, Wei
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- Oxidative homocoupling reaction of aryltrimethylsilanes by Pd/o-chloranil catalysis
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A practical oxidative homocoupling reaction of aryltri-methylsilanes has been achieved by Pd/o-chloranil catalytic system. The reaction shows the good functional group tolerability toward bromo, fluoro, ester, and methoxy groups to give a series of biaryls bearing electron-withdrawing and -donating groups. The boronate group is also retained on biaryls without any ArB bond cleavage, which is highly advantageous for orthogonal coupling.
- Shibata, Mari,Ito, Hideto,Itami, Kenichiro
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supporting information
p. 1701 - 1704
(2017/11/23)
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- Palladium-catalyzed reductive homocoupling of aryl sulfonates via cleavage of C─O bond at room temperature
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Palladium-catalyzed reductive homocoupling of aryl sulfonates has been successfully achieved under mild conditions. This transformation is a new method for the homocoupling reaction of aryl sulfonates at room temperature via the cleavage of C─O bonds, thus providing an alternative synthesis of symmetric biaryls. The reported reductive homocoupling reaction is tolerant of many common functional groups regardless of electron-donating or electron-withdrawing nature, making this newly developed transformation important for complementing Ullmann coupling. Experimental Section. Typical procedure for the products.
- Zhong, Shuangling,Chen, Mengxin,Liu, Ge,Sun, Chenggang,Liu, Wencong
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- Resorcinarene-Based o-Biarylphosphines in Palladium-Catalysed Suzuki–Miyaura Cross-Coupling Reactions of Bulky Substrates
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Two o-biarylphosphines, in which the arene ring remote from the phosphorus atom is part of a resorcin[4]arene cavitand, have been synthesised, characterised by X-ray diffraction and assessed in the cross-coupling reactions of bulky aryl chlorides with sterically hindered arylboronic acids. Only atropisomers with externally located P atoms were obtained. The resorcinarene ligand with the o-PCy2C6H4substituent was found to be more efficient than the Buchwald analogue SPhos in catalysing coupling reactions, reacting around 1.4 times faster. Its superior performance has been attributed to the permanent exo positioning of the metal centre, which engenders steric interactions with two pentyl substituents and therefore facilitates the reductive elimination step.
- Elaieb, Fethi,Sémeril, David,Matt, Dominique
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supporting information
p. 685 - 693
(2017/02/05)
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- Palladium Nanoparticles Supported on a Porous Organic Polymer: An Efficient Catalyst for Suzuki-Miyaura and Sonogashira Coupling Reactions
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A new porous organic polymer (POP) with high thermal stability and large surface area has been synthesized and applied in the preparation of Pd/POP catalyst. Pd/POP was characterized by XRD, TGA, SEM and TEM. The catalyst consists of highly dispersed palladium nanoparticles of 0.9-4 nm size on POP with a large surface area of 650 m2/g. It presents high catalytic activity for Suzuki-Miyaura and Sonogashira reactions. The catalyst was reusable for three to five times without significant loss of activity. A new porous organic polymer (POP) was synthesized and applied in the preparation of Pd/POP catalyst. Pd/POP exhibits high catalytic activity for Suzuki-Miyaura and Sonogashira reactions and is reusable in these heterogeneous catalytic reactions.
- Ren, Xiaomeng,Kong, Shengnan,Shu, Qiding,Shu, Mouhai
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p. 373 - 380
(2016/04/26)
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- Homocoupling reactions of terminal alkynes and arylboronic compounds catalyzed by in situ formed Al(OH)3-supported palladium nanoparticles
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Palladium nanoparticles supported on newly generated Al(OH)3was found to be a highly efficient catalyst in oxidative homo-couplings of (Het)aryl alkynes, (Het)arylboronic acids and potassium (Het)aryltrifluoroborates, respectively. Moderate to excellent yields of symmetrical 1,3-diynes and biaryls were obtained under mild conditions.
- Li, Xing,Li, Dongjun,Bai, Yana,Zhang, Congxia,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
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supporting information
p. 6996 - 7002
(2016/10/14)
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- A Copper-Based Metal-Organic Framework Acts as a Bifunctional Catalyst for the Homocoupling of Arylboronic Acids and Epoxidation of Olefins
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A copper(I)-based metal-organic framework ({[Cu2Br2(pypz)]na.nH2O} (Cu-Br-MOF) [pypz=bis[3,5-dimethyl-4-(4'-pyridyl)pyrazol-1-yl] methane] has been synthesized by using an elongated and flexible bridging ligand. The structure analysis reveals that each pypz ligand acts as a tritopic ligand connected to two Cu2Br2 dimeric units, forming a one-dimensional zig-zag chain, and these chains further connected by a Cu2Br2 unit, give a two-dimensional framework on the bc-plane. In the Cu2Br2 dimeric unit, the copper ions are four coordinated, thereby possessing a tetrahedral geometry; this proves to be an excellent heterogeneous catalyst for the aerobic homocoupling of arylboronic acids under mild reaction conditions. This method requires only 3 mol % of catalyst and it does not require any base or oxidant-compared to other conventional (Cu, Pd, Fe, and Au) catalysts-for the transformation of arylboronic acids in very good yields (98 %). The shape and size selectivity of the catalyst in the homocoupling was investigated. The use of the catalyst was further extended to the epoxidation of olefins. Moreover, the catalyst can be easily separated by simple filtration and reused efficiently up to 5 cycles without major loss of reactivity.
- Parshamoni, Srinivasulu,Telangae, Jyothi,Sanda, Suresh,Konar, Sanjit
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p. 540 - 547
(2016/03/12)
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- Miyaura Borylation and One-Pot Two-Step Homocoupling of Aryl Chlorides and Bromides under Solvent-Free Conditions
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Solvent-free protocols for Miyaura borylation and the one-pot, two-step homocoupling of aryl halides are reported for the first time. Bis(dibenzylideneacetone)palladium(0) [Pd(dba)2] is an optimal source of palladium for Miyaura borylation, while for one-pot two-step homocoupling palladium(II) acetate [Pd(OAc)2] gives highest yields. Aryl bromides are coupled most efficiently using the DPEphos ligand. Chlorides are coupled using XPhos. The developed protocols are robust, versatile and easily reproducible on a large scale.
- Dzhevakov, Pavel B.,Topchiy, Maxim A.,Zharkova, Daria A.,Morozov, Oleg S.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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p. 977 - 983
(2016/04/05)
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- Palladium-Catalyzed, tert-Butyllithium-Mediated Dimerization of Aryl Halides and Its Application in the Atropselective Total Synthesis of Mastigophorene A
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A palladium-catalyzed direct synthesis of symmetric biaryl compounds from aryl halides in the presence of tBuLi is described. In situ lithium-halogen exchange generates the corresponding aryl lithium reagent, which undergoes a homocoupling reaction with a second molecule of the aryl halide in the presence of the palladium catalyst (1 mol %). The reaction takes place at room temperature, is fast (1 h), and affords the corresponding biaryl compounds in good to excellent yields. The application of the method is demonstrated in an efficient asymmetric total synthesis of mastigophorene A. The chiral biaryl axis is constructed with an atropselectivity of 9:1 owing to catalyst-induced remote point-to-axial chirality transfer. It takes two: A palladium-catalyzed direct homocoupling of aryl halides in the presence of tBuLi enabled the synthesis of even tetra-ortho-substituted symmetric biaryl compounds in high yield (see scheme). The method was applied to the asymmetric synthesis of mastigophorene A in just eight steps through straightforward enantioselective installation of the benzylic quaternary stereocenter and highly diastereoselective homocoupling.
- Buter, Jeffrey,Heijnen, Dorus,Vila, Carlos,Hornillos, Valentín,Otten, Edwin,Giannerini, Massimo,Minnaard, Adriaan J.,Feringa, Ben L.
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supporting information
p. 3620 - 3624
(2016/03/23)
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- The design of second generation MOP-phosphonites: Efficient chiral hydrosilylation of functionalised styrenes
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A series of enantiopure MOP-phosphonite ligands, with tailored steric profiles, have been synthesised and are proven to be very successful in high-yielding, regio- and enantioselective catalytic hydrosilylation reactions of substituted styrenes, affording important chiral secondary alcohols.
- Fleming, James T.,Ficks, Arne,Waddell, Paul G.,Harrington, Ross W.,Higham, Lee J.
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supporting information
p. 1886 - 1890
(2016/02/09)
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- A modified Cu(0)-Cu(I)-mediated Caryl-CarylUllmann coupling for the synthesis of biaryls
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A novel Cu(0)-Cu(I)-mediated Caryl-CarylUllmann coupling has been successfully developed. The use of Cu(I) salts allowed the reactions to proceed under relatively mild conditions (65?°C in DMSO for 15–72?h). The developed method was compatible with a relatively wide range of functional groups simultaneously present on the aromatic ring of different electronic nature. The aryl halides with an electron-withdrawing group ortho to the halide or an electron-donating group meta or para to the halide furnished the corresponding products in good to excellent yields (up to 98%).
- Yasamut, Kittisak,Jongcharoenkamol, Jira,Ruchirawat, Somsak,Ploypradith, Poonsakdi
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p. 5994 - 6000
(2016/09/14)
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- Cobalt-Catalyzed Oxidative Homocoupling of Arylzinc Species
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A novel procedure for the synthesis of functionalized symmetrical biaryl compounds is described. The reaction proceeds via the oxidative homocoupling of arylzinc species formed by cobalt catalysis in the presence of air or p-benzoquinone depending on the nature of the functional group.
- Bourne-Branchu, Yann,Moncomble, Aurélien,Corpet, Martin,Danoun, Gregory,Gosmini, Corinne
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p. 3352 - 3356
(2016/09/12)
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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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- Pd-PEPPSI Complexes bearing bulky [(1,2-Di-(tert-butyl)acenaphthyl] (DtBu-An) on N-heterocarbene backbones: Highly efficient for suzuki-miyaura cross-coupling under aerobic conditions
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With the goal of achieving highly efficient palladium-catalyzed cross-coupling reactions under mild reaction conditions, the Pd-PEPPSI complexes C1 and C2 bearing 1,2-di(tert-butyl)acenaphthyl (DtBu-An) backbones were synthesized and characterized, and their use in Suzuki-Miyaura cross-coupling was investigated. The effects of catalyst structure and reaction conditions on the cross-coupling efficiency were evaluated in detail. The significant differences in catalytic activity compared with classical PEPPSI-IPr and PEPPSI-IPrAn precatalysts are discussed, where the axial sterics on the backbone play an important role. At low palladium loadings of 0.05-0.1 mol % and upon the addition of the relatively weak base K3PO4, the palladium complex C1 was found to be highly efficient for the coupling of (hetero)aryl chlorides with arylboronic acids under aerobic conditions, affording the corresponding biaryls in excellent yields.
- Lan, Xiao-Bing,Chen, Fu-Min,Ma, Bei-Bei,Shen, Dong-Sheng,Liu, Feng-Shou
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p. 3852 - 3860
(2016/12/07)
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- The Influence of Imidazolylidene Ligands with Bulky Resorcinarenyl Substituents on Catalysts for Suzuki-Miyaura Coupling
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PEPPSI-type imidazolylidene palladium complexes having their carbenic ring N-substituted with an aryl ring and a cavity-shaped unit [25,26,27,28-tetrapropyloxycalix[4]aren-5-yl or 6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]aren-5-yl (TPR)] have been prepared and assessed in Suzuki-Miyaura cross-couplings. Remarkable efficiency in the coupling of aryl chlorides with sterically hindered arylboronic acids was observed for the carbene ligand having its N atoms (N1, N2) substituted by a mesityl and a TPR group, respectively. This good performance possibly arises from strong steric interactions between the pentyl-substituted cavitand unit and the catalytic centre, which favours reductive elimination. Two of the imidazolium salts used for complex synthesis were characterised by X-ray diffraction analysis.
- Kalo?lu, Murat,Sémeril, David,Brenner, Eric,Matt, Dominique,?zdemir, Ismail,Toupet, Lo?c
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p. 1115 - 1120
(2016/03/15)
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- Arylcalixarenyl Phosphines in Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions
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Two electron-rich arylcalixarenylphosphines have been synthesized in three steps from the appropriate 5-bromocalix[4]arene precursor 1. The combination of 5-(2-diisopropylphosphinophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (5) and 5-(2-dicyclohexylphosphinophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (6), respectively, with [Pd2(dba)3] (dba = dibenzylideneacetone) generated effective catalysts for the cross-coupling reactions of hindered aryl chlorides and arylboronic acids. Dicyclohexylphosphino-substituted ligand 6 had a higher activity that that of 5, and the structures of ligand 5 and [AuCl·5] were determined by single-crystal X-ray diffraction studies. The solid-state structure of [AuCl·5] revealed that the gold atom lies above the outer face of the calixarene unit, with distances of 3.08 and 3.28 ? between the gold atom and the two closest aromatic carbon atoms of the calixarene moiety.
- Elaieb, Fethi,Hedhli, Ahmed,Sémeril, David,Matt, Dominique
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supporting information
p. 1867 - 1873
(2016/05/09)
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- Ligand-, base-, co-catalyst-free copper fluorapatite (CuFAP) as a versatile, ecofriendly, heterogeneous and reusable catalyst for an efficient homocoupling of arylboronic acid at ambient reaction conditions
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This paper describes the first report in which copper species containing copper fluorapatite (CuFAP) acts as a versatile, eco-friendly, recyclable, heterogeneous catalyst for an efficient synthesis of symmetric biaryls from the homo-coupling of arylboronic acids in methanol solvent at ambient reaction conditions. The developed protocol is ligand-, base-, and co-catalyst-free, sustainable, mild, inexpensive, and compatible with a wide range of aromatic/heterocyclic boronic acids and provides the corresponding products in excellent yields without purification. The catalyst was easily recovered from the reaction mixture and reused several times without loss of activity.
- Mulla, Shafeek A. R.,Chavan, Santosh S.,Pathan, Mohsinkhan Y.,Inamdar, Suleman M.,Shaikh, Taufeekaslam M. Y.
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p. 24675 - 24680
(2015/03/30)
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- In water homocoupling of arylboronic acids using nano-rod shaped and reusable copper oxide(II) catalyst at room temperature
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The work describes a simple in situ soft chemical synthesis of rod shaped nano CuO, characterization and study of its catalytic performance in the aerobic homocoupling of arylboronic acids to synthesize symmetrical biphenyls. The catalyst is simple to prepare, environmentally benign, efficient, easy recovery, reusable, stable and heterogeneous in nature.
- Raul, Prasanta Kumar,Mahanta, Abhijit,Bora, Utpal,Thakur, Ashim Jyoti,Veer, Vijay
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p. 7069 - 7073
(2015/12/01)
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- Oxidative homocoupling of arylboronic acids catalyzed by a 4-aminoantipyrine-Pd(II)complex
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A one-step synthesis of symmetric biaryls is reported under very mild conditions via the homocoupling reaction of substituted arylboronic acids using an air- and moisture-stable 4-aminoantipyrine-Pd(II) complex as catalyst. The reaction is conducted at a low catalyst loading of 0.1 mol% at room temperature in methanol in the presence of K2CO3 as the base and KMnO4 as the oxidant. The catalytic methodology is shown to be compatible with diverse functional groups and affords the desired biphenyls in good to excellent yields.
- Contreras-Celedón, Claudia Araceli,Rincón-Medina, José Arturo,Mendoza-Rayo, Darío,Chacón-García, Luis
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p. 439 - 442
(2015/06/30)
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- Recyclable and reusable Pd(OAc)2/PPh3/PEG-2000 system for homocoupling reaction of arylboronic acids under air without base
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A stable and efficient Pd(OAc)2/PPh3/PEG-2000 catalytic system for homocoupling of arylboronic acids has been developed. In the presence of Pd(OAc)2 and PPh3, the homocoupling reaction of arylboronic acids was carried out smoothly in PEG-2000 at 70°C under air without base to afford a variety of symmetric biaryls in good to excellent yields. The isolation of the products was readily performed by extractionwith diethyl ether, and the Pd(OAc)2/PPh3/PEG-2000 systemcould be easily recycled and reused six times without significant loss of catalytic activity.
- Xia, Jianhui,Cheng, Mingzhu,Chen, Qiurong,Cai, Mingzhong
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p. 113 - 116
(2015/01/30)
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- Immobilization of Pd(II) on MOFs as a highly active heterogeneous catalyst for Suzuki-Miyaura and Ullmann-type coupling reactions
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Palladium chloride was successfully immobilized on MOF-253, a MOF material with un-coordinated 2,2′-bipyridine moieties, through post-synthetic modification. The coordination interaction between the 2,2′-bipyridine moieties and Pd cations in the MOF-253·PdCl2 material was demonstrated by X-ray photoelectron spectroscopy (XPS) analysis. The prepared MOF-253·0.05PdCl2 was shown to be highly active, selective, and recyclable for the Suzuki-Miyaura cross-coupling and Ullmann homocoupling of a wide range of aryl halides including electron-rich and electron-poor aryl iodides/bromides, heteroaryl iodides, and even aryl chlorides, affording the corresponding biaryl compounds in good to excellent yields under mild reaction conditions. It is suggested that the 2,2′-bipyridine moieties in MOF-253 provide electron-rich environment for Pd(II) cations, and thus facilitate the initial adsorption and insertion of aryl halides molecules to Pd active sites during the carbon-carbon coupling reactions. Moreover, MOF-253·PdCl2 showed remarkably higher activity than the homogeneous Pd(bpy)Cl2 and PdCl2(CH3CN)2, which might be due to the presence of charge transfers between adjacent ligands and metals in the MOF catalyst. The superior catalytic performances of metal ions immobilized on MOFs to their homogenous counterparts might bring new opportunities in the development of highly efficient metal catalysts combining advantages of both homogeneous and heterogeneous catalysis.
- Chen, Liyu,Gao, Zhiqiang,Li, Yingwei
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p. 122 - 128
(2015/03/04)
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- Synthesis and reactions of PdII complexes with aryl, aroyl, and iminoaroyl ligands - Insertion of CO and RNC into the Pd-Ar bond and intermolecular coupling of the ligands
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The arylpalladium(II) complexes [PdIAr(bpy)] (Ar = Ph, C6H3-3,5-Me2, C6H4-4-OMe, C6H4-2-OMe, C6H4-4-C6H4-4-I, 1-naphthyl; bpy = 2,2′-bipyridine) undergo insertion of CO and CNR (R = tBu, C6H3-2,6-Me2) into the Pd-aryl bond to produce [PdI(COAr)(bpy)] and [PdI{C(=N-R)Ar}(bpy)]. The dinuclear complex [C6H3-3,5-{(OCH2CH2)2C6H4-3-PdI(bpy)}2] is synthesized by the oxidative addition reaction of 1,3-bis[(3-iodophenyl)-1,4,7-trioxaheptyl]benzene to [Pd(dba)2] (dba = dibenzylideneacetone). The addition of AgBF4 to the arylpalladium(II) complexes [PdIAr(bpy)] (Ar = C6H4-4-OMe, C6H4-2-OMe, 1-naphthyl) produces the intermolecular coupling products of the aryl ligands, Ar-Ar. The reactions of AgBF4 with the aroylpalladium(II) complexes [PdI(COAr)-(bpy)] (Ar = C6H3-3,5-Me2, C6H4-2-OMe) result in decarbonylation and intermolecular coupling of the ligands to yield the diarylketones. The iminoaroylpalladium(II) complex [PdI{C(=NtBu)C6H3-3,5-Me2}(bpy)] undergoes hydrolysis of the ligand to yield tBuNHCO(C6H3-3,5-Me2). The addition of AgBF4 to the dinuclear complex [C6H3-3,5-{(OCH2CH2)2C6H4-3-PdI(bpy)}2] yields a mixture of the cyclic oligomers cyclo-[C6H3-3,5-{(OCH2CH2)2C6H4-3-}2]n (n = 1-4) by inter- and intramolecular coupling of the aryl ligands.
- Suzaki, Yuji,Shirokawa, Masanori,Yagyu, Takeyoshi,Osakada, Kohtaro
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p. 421 - 429
(2015/02/05)
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- Controlling the Course of a Two-Way Switchable Pd-Catalyzed Process by means of Empirical Multivariate Models
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A two-way switchable Pd-catalyzed process that can pursue two different mechanisms, namely hydro- and methoxy-deiodination was discovered, developed, and optimized by means of statistical experimental design, multivariate modelling, and response surface methodology. The investigation revealed that the two-way switchable process might be controlled either by ligand alone, or by ligand and other process variables in combination. The present study represents the first example of a catalytic system that provides either hydro- or methoxy-deiodination selectively by simply fine-tuning the experimental variables.
- Sandtorv, Alexander H.,Bj?rsvik, Hans-René
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p. 2196 - 2205
(2015/11/24)
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- Pd-Catalyzed Cross-Coupling of Aryllithium Reagents with 2-Alkoxy-Substituted Aryl Chlorides: Mild and Efficient Synthesis of 3,3′-Diaryl BINOLs
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Palladium-catalyzed cross-coupling of aryllithium reagents with 2-alkoxy-substituted aryl chlorides is described. The reactions proceed under mild conditions with short reaction times and provide a wide range of 2-alkoxy-substituted biaryls. This new methodology is applied to the efficient preparation of 3,3′-diaryl BINOLs and represents the first synthesis of this important class of chiral compounds from the corresponding 3,3′-dichloro BINOLs. (Chemical Equation Presented).
- Castelló, Luis M.,Hornillos, Valentín,Vila, Carlos,Giannerini, Massimo,Fa?anás-Mastral, Martín,Feringa, Ben L.
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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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supporting information
p. 2385 - 2388
(2015/10/19)
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- In situ-generated nano-palladium-catalyzed ligand-free Suzuki-Miyaura reaction of potassium aryltrifluoroborates at room temperature
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A mild and simple protocol is described for the palladium-catalyzed ligand-free Suzuki-Miyaura reaction of potassium aryltrifluoroborates in aqueous ethanol at room temperature. Palladium nanoparticles are generated in situ in the reaction and demonstrate high activity towards a wide range of aryl bromides and potassium aryltrifluoroborates, providing biphenyls in good to excellent yields. Interestingly, only 1 equiv of K2CO3 is used in this catalytic system. Moreover, the key biaryl intermediate of 2-cyano-4′-methylbiphenyl within valsartan is prepared in a 95% yield after 2 h.
- Liu, Chun,Li, Xinmin,Gao, Zhanming,Wang, Xinnan,Jin, Zilin
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supporting information
p. 3954 - 3959
(2015/06/02)
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