- Synthesis of biaryls via unusual deoxygenative dimerization of 1,4-epoxy-1,4-dihydroarenes catalyzed by palladium complexes
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matrix presented Treatment of various 1,4-epoxy-1,4-dihydroarenes with trichlorosilane in toluene in the presence of a palladium complex affords the corresponding biaryls in good to excellent yields. The process appears to occur via a novel palladium-catalyzed hydrosilylative dimerization of 1,4-epoxy-1,4-dihydroarenes and subsequent elimination of HOSiCl3 and H2O.
- Shih, Huai-Ting,Shih, Hung-Hsin,Cheng, Chien-Hong
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- Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox-Switchable 20π, 19π, and 18π 5,10,15,20-Tetraaryl-5,15-diazaporphyrinoids
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In spite of significant advances in redox-active porphyrin-based materials and catalysts, little attention has been paid to 20π and 19π porphyrins because of their instability in air. Here we report the meso-modification of 5,10,15,20-tetraarylporphyrin with two nitrogen atoms, which led to redox-switchable 20π, 19π, and 18π 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (TADAPs). Three kinds of metal(II) complexes and free bases of TADAP were prepared by the metal-templated annulation of the corresponding metal-bis(dipyrrin) complexes. The inductive and resonance effects of the meso-nitrogen atoms on the aromatic, optical, electrochemical, and magnetic properties of the entire TADAP π-systems were assessed by using various spectroscopic measurements and density functional theory calculations. The aromaticity and π–π* electronic transition energies of the TADAPs varied considerably, and were shown to be dependent on the oxidation states of the π-systems. In contrast to the isoelectronic 5,10,15,20-tetraarylporphyrin derivatives, the 20π and 19π TADAPs were chemically stable under air. In particular, the 19π TADAP radical cations were extremely stable towards dioxygen, moisture, and silica gel. This reflected the low-lying singly occupied molecular orbitals of their π-systems and the efficient delocalization of their unshared electron spin. The capability of MgTADAP to catalyze aerobic biaryl formation from aryl Grignard reagents was demonstrated, which presumably involved a 19π/20π redox cycle.
- Sudoh, Keisuke,Satoh, Takaharu,Amaya, Toru,Furukawa, Ko,Minoura, Mao,Nakano, Haruyuki,Matano, Yoshihiro
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- Visible Light Induced Aerobic Coupling of Arylboronic Acids Promoted by Hydrazone
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A visible-light-induced oxidative coupling of arylboronic acids has been developed for the synthesis of biaryls. The reaction that employs polydentate hydrazones as the bifunctional catalyst works smoothly under room temperature. It is compatible with a w
- Wang, Ganghu,Xia, Hongyu,Zhao, Dongbo,Zhu, Chunyin
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supporting information
(2022/02/10)
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- Reductive Coupling of Aryl Halides via C—H Activation of Indene
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This paper describes the first case of a reductive coupling reaction with indene, a non-heteroatom olefin used as a reducing agent. The scope of the substrate is wide. The homo-coupling, cross-coupling, and synthesis of 12 and 14-membered rings were realized. The control experiment, indene-product curve and density functional theory calculations showed that the η3-palladium indene intermediate was formed by C—H activation in the presence of cesium carbonate. We speculate that the final product was obtained through a Pd (IV) intermediate or aryl ligand exchange. In addition, we excluded the formation of palladium anion (Pd(0)?) intermediates.
- Zhang, Bo-Sheng,Yang, Ying-Hui,Wang, Fan,Gou, Xue-Ya,Wang, Xi-Cun,Liang, Yong-Min,Li, Yuke,Quan, Zheng-Jun
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p. 1573 - 1579
(2021/05/28)
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- Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C-H amidation reactions
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A mild, efficient electrochemical approach to the site-selective direct C-H amidation of benzene and its derivatives with acetonitrile and benzonitrile has been developed. It has been shown that joint electrochemical oxidation of various arenes in the presence of a copper salt as a catalyst and nitriles leads to the formation of N-phenylacetamide from benzene and N-benzylacetamides from benzyl derivatives (up to 78% yield). A favorable feature of the process is mild conditions (room temperature, ambient pressure, no strong oxidants) that meet the criteria of green chemistry.
- Budnikova, Yulia,Kononov, Alexander,Rizvanov, Ildar,Strekalova, Sofia
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p. 37540 - 37543
(2021/12/07)
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- The Anionic Pathway in the Nickel-Catalysed Cross-Coupling of Aryl Ethers
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The Ni-catalysed cross-coupling of aryl ethers is a powerful method to forge new C?C and C?heteroatom bonds. However, the inert C(sp2)?O bond means that a canonical mechanism that relies on the oxidative addition of the aryl ether to a Ni0 centre is thermodynamically and kinetically unfavourable, which suggests that alternative mechanisms may be involved. Here, we provide spectroscopic and structural insights into the anionic pathway, which relies on the formation of electron-rich hetero-bimetallic nickelates by adding organometallic nucleophiles to a Ni0 centre. Assessing the rich co-complexation chemistry between Ni(COD)2 and PhLi has led to the structures and solution-state chemistry of a diverse family of catalytically competent lithium nickelates being unveiled. In addition, we demonstrate dramatic solvent and donor effects, which suggest that the cooperative activation of the aryl ether substrate by Ni0-ate complexes plays a key role in the catalytic cycle.
- Borys, Andryj M.,Hevia, Eva
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supporting information
p. 24659 - 24667
(2021/10/20)
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- Oxidative Intramolecular C-C Bond Formation Reactions of 1,2-Diarylbenzenes: Syntheses of Highly Conjugated Double-Bridged Polycyclic Aromatic Hydrocarbons
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Oxidation reactions of 1,2-diarylbenzenes induce intramolecular C-C bond formation. The substrates studied were prepared by the stepwise Suzuki-Miyaura coupling reaction that introduced 2-naphthyl, 2-anthranyl, and 2-pyrenyl groups on the ortho -positions
- Hirabayashi, Kazunori,Islam, Md. Rafikul,Nishinaga, Tohru,Shimizu, Toshio,Sugiura, Ken-Ichi
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- Ni-Catalyzed Aryl Sulfide Synthesis through an Aryl Exchange Reaction
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A Ni-catalyzed aryl sulfide synthesis through an aryl exchange reaction between aryl sulfides and a variety of aryl electrophiles was developed. By using 2-pyridyl sulfide as a sulfide donor, this reaction achieved the synthesis of aryl sulfides without using odorous and toxic thiols. The use of a Ni/dcypt catalyst capable of cleaving and forming aryl-S bonds was important for the aryl exchange reaction between 2-pyridyl sulfides and aryl electrophiles, which include aromatic esters, arenol derivatives, and aryl halides. Mechanistic studies revealed that Ni/dcypt can simultaneously undergo oxidative additions of aryl sulfides and aromatic esters, followed by ligand exchange between the generated aryl-Ni-SR and aryl-Ni-OAr species to furnish aryl exchanged compounds.
- Isshiki, Ryota,Kurosawa, Miki B.,Muto, Kei,Yamaguchi, Junichiro
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supporting information
p. 10333 - 10340
(2021/07/21)
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- Nickel-Catalyzed Homocoupling of Aryl Ethers with Magnesium Anthracene Reductant
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Nickel-catalyzed reductive homocoupling of aryl ethers has been achieved with Mg(anthracene)(thf) 3as a readily available low-cost reductant. DFT calculations provided a rationale for the specific efficiency of the diorganomagnesium-type two-electron reducing agent. The calculations show that the dianionic anthracene-9,10-diyl ligand reduces the two aryl ether substrates, resulting in the homocoupling reaction through supply of electrons to the Ni-Mg bimetallic system to form organomagnesium nickel(0)-ate complexes, which cause two sequential C-O bond cleavage reactions. The calculations also showed cooperative actions of Lewis acidic magnesium atoms and electron-rich nickel atoms in the C-O cleavage reactions.
- Rawat, Vishal Kumar,Higashida, Kosuke,Sawamura, Masaya
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supporting information
p. 3397 - 3403
(2021/06/28)
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- MICRO-ELECTROLYSIS REACTOR FOR ULTRA FAST, OXIDANT FREE, C-C COUPLING REACTION AND SYNTHESIS OF DACLATASVIR ANALOGS THEREOF
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The present invention relates to a continuous micro-electro-flow reactor system for ultra-fast, oxidant free, C—C coupling reaction for making symmetrical biaryls and analogs thereof. This invention further relates to the said process for preparation of antiviral drug, daclatasvir of general formula I.
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Paragraph 0105-0110; 0127-0132
(2020/12/01)
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- Exploration of mechanochemical activation in solid-state fluoro‐grignard reactions
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Owing to the strength of the C–F bond, the ‘direct’ preparation of Grignard reagents, i.e., the interaction of elemental magnesium with an organic halide, typically in an ethereal solvent, fails for bulk magnesium and organofluorine compounds. Previously described mechanochemical methods for preparing Grignard reagents have involved ball milling powdered magnesium with organochlorines or bromines. Activation of the C–F bond through a similar route is also possible, however. For example, milling 1- and 2-fluoronaphthalene with an excess of magnesium metal for 2 h, followed by treatment with FeCl3 and additional milling, produces the corresponding binaphthalenes, albeit in low yields (ca. 20%). The yields are independent of the particular isomer involved and are also comparable to the yields from corresponding the bromonaphthalenes. These results may reflect similar charges that reside on the α-carbon in the naphthalenes, as indicated by density functional theory calculations.
- Hanusa, Timothy P.,Speight, Isaiah R.
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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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- Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
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A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
- Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
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p. 254 - 258
(2020/01/25)
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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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- Reductive Cross-Coupling between Unactivated C(aryl)-N and C(aryl)-O Bonds by Chromium Catalysis Using a Bipyridyl Ligand
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Reductive cross-coupling between two chemically inert bonds remains a great challenge in synthetic chemistry. We report here the reductive cross-coupling between unactivated C(aryl)-N and C(aryl)-O bonds that was achieved by chromium catalysis. The simple and inexpensive CrCl2 salt, combined with important bipyridyl ligand and magnesium reductant, shows high reactivity in the successive cleavage of C(aryl)-N bonds of aniline derivatives and C(aryl)-O bonds of aryl esters, allowing the cross-coupling of these two unactivated and different bonds to occur in a reductive fashion to form a C(aryl)-C(aryl) bond. Mechanistic studies by deuterium-labeling experiments indicate that the C(aryl)-N bonds in anilines are preferentially cleaved by reactive Cr species, in which the ligation of bipyridyl with Cr by adopting a coordination model in 1:1 ratio can be considered.
- Cong, Xuefeng,Fan, Fei,Luo, Meiming,Tang, Jinghua,Zeng, Xiaoming,Zhao, Lixing
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supporting information
p. 12834 - 12840
(2020/08/21)
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- C-F activation for C(sp2)-C(sp3) cross-coupling by a secondary phosphine oxide (SPO)-nickel complex
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A secondary phosphine oxide (SPO)-nickel catalyst allowed the activation of otherwise inert C-F bonds of unactivated arenes in terms of challenging couplings with primary and secondary alkyl Grignard reagents. The C-F activation is characterized by mild reaction conditions and high levels of branched selectivity. Electron-rich and electron-deficient arenes were suitable electrophiles for this transformation. In addition, this strategy also proved suitable to heterocycles and for the activation of C-O bonds under slightly modified conditions.
- Müller, Valentin,Ghorai, Debasish,Capdevila, Lorena,Messinis, Antonis M.,Ribas, Xavi,Ackermann, Lutz
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supporting information
p. 7034 - 7040
(2020/09/15)
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- Transition-Metal-Free Oxidative Cross-Coupling of Tetraarylborates to Biaryls Using Organic Oxidants
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Readily prepared tetraarylborates undergo selective (cross)-coupling through oxidation with Bobbitt's salt to give symmetric and unsymmetric biaryls. The organic oxoammonium salt can be used either as a stoichiometric oxidant or as a catalyst in combination with in situ generated NO2 and molecular oxygen as the terminal oxidant. For selected cases, oxidative coupling is also possible with NO2/O2 without any additional nitroxide-based cocatalyst. Transition-metal-free catalytic oxidative ligand cross-coupling of tetraarylborates is unprecedented and the introduced method provides access to various biaryl and heterobiaryl systems.
- Gerleve, Carolin,Studer, Armido
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supporting information
p. 15468 - 15473
(2020/05/06)
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- Chemoselective Cross-Coupling between Two Different and Unactivated C(aryl)-O Bonds Enabled by Chromium Catalysis
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We report here the first example of cross-coupling between two different and unactivated C(aryl)-O bonds with chromium catalysis. The combination of a low-cost Cr(II) salt, 4,4′-di-tert-butyl-2,2′-dipyridyl (dtbpy) as the ligand, and magnesium as the reductant shows high reactivity in promoting the reductive cross-coupling of aryl methyl ether derivatives with aryl esters by cleavage and coupling of two different C(aryl)-O bonds under mild conditions. The formation of active low-valent Cr species by reduction of CrCl2 with Mg can be considered, which prefers to initially activate the C(aryl)-O bond of phenyl methyl ether with the chelation help of dtbpy and an o-imine auxiliary. The subsequent consecutive reduction, second C(aryl)-O activation, and reductive elimination allow for the achievement of selective cross-coupling of C(aryl)-O/C(aryl)-O bonds.
- Tang, Jinghua,Liu, Liu Leo,Yang, Shangru,Cong, Xuefeng,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 7715 - 7720
(2020/05/20)
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- Micro-electro-flow reactor (μ-EFR) system for ultra-fast arene synthesis and manufacture of daclatasvir
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The World Health Organization (WHO) has listed daclatasvir (DCV), symmetrical arene, as one of the essential medicines for human health. DCV manufacturing is usually carried out in a non-continuous or "batch" approach over multiple locations and is severely limited by long production times (3-10 days), resulting in non-affordability (highly expensive) and disruption of the potential chain supply. Here, we report the total process system including the development of a novel electro-flow reactor containing patterned electrodeposited Ni or Pt nanoparticles over a copper electrode for a C-C coupling reaction in a co-reductant/oxidant-free, ultra-fast process for symmetrical substituted/unsubstituted biphenyl synthesis. This method was further extended to a new generation commercial batch synthetic route for continuous flow ultra-fast daclatasvir synthesis in 33.2 min. We envisage that this micro-electro-flow reactor (μ-EFR) system platform will substantially enable advances in continuous-μ-flow fine chemical manufacturing, multistep reaction sequences, reaction devising equipment, and real-time extraction.
- Mahajan, Bhushan,Mujawar, Taufiqueahmed,Ghosh, Subhash,Pabbaraja, Srihari,Singh, Ajay K.
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p. 11852 - 11855
(2019/10/11)
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- Synergistic Activities in the Ullmann Coupling of Chloroarenes at Ambient Temperature by Pd-Supported Calcined Ferrocenated La2O3
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Novel palladium-doped nanoparticles have been explored to serve as the first metal oxide-derived heterogeneous catalyst for Ullmann reaction of chloroarenes under mild condition (34?°C). This heterogeneous catalyst exhibited high catalytic activity towards the Ullmann homocoupling of chloroarenes into a series of useful symmetrically biaryl products with good to excellent yields in the presence of ethanol and NaOH, thereby leading to green and economical Ullmann reaction. The produced nanoparticles were successfully characterized by various techniques including PXRD, XPS, HRTEM, SEM-EDS, BET, TGA techniques, elemental mapping analysis and ICP-OES. Interestingly, based on characterization and experimental data, a reasonable mechanism has been proposed. Also, the formation of aryl methyl ketone as a by-product has been further confirmed by isotopic labelling experiments that the acetyl moiety is derived from ethanol. Moreover, the catalyst was stable and could be easily reused up to 5 times under atmospheric air without suffering significant loss in catalytic activity.
- Chumkaeo, Peerapong,Poonsawat, Thinnaphat,Meechai, Titiya,Somsook, Ekasith
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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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- Sterically controlled C-H/C-H homocoupling of arenes: Via C-H borylation
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A mild one-pot protocol for the synthesis of symmetrical biaryls by sequential Ir-catalyzed C-H borylation and Cu-catalyzed homocoupling of arenes is described. The regiochemistry of the biaryl formed is sterically controlled as dictated by the C-H borylation step. The methodology is also successfully extended to heteroarenes. Some of the products obtained by this approach are impossible to obtain via the Ullmann or the Suzuki coupling protocols. Finally, we have shown a one-pot sequence describing C-H borylation/Cu-catalyzed homocoupling/Pd-catalyzed Suzuki coupling to obtain π-extended arene frameworks.
- Pei, Xiaocong,Zhou, Guan,Li, Xuejing,Xu, Yuchen,Panicker, Resmi C.,Srinivasan, Rajavel
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p. 5703 - 5707
(2019/06/19)
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- Nickel Carbodicarbene Catalyzes Kumada Cross-Coupling of Aryl Ethers with Grignard Reagents through C–O Bond Activation
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The development of a cross-coupling reaction protocol between aryl ethers and Grignard reagents catalyzed by carbodicarbene (CDC) nickel complexes to afford biaryl compounds through C–O cleavage is reported. Aromatic substrates featuring a broad range of electron neutral, donating, or withdrawing groups are introduced at the desired position. The method has proven effective over a wide range of naphthyl methyl ethers, anisoles, and Grignard reagents. The robustness of the protocol is validated by performing multiple cleavage reactions, gram scale synthesis, and arylation of a dimethoxy esterdiol derivative.
- Ambre, Ram,Yang, Hsuan,Chen, Wen-Ching,Yap, Glenn P. A.,Jurca, Titel,Ong, Tiow-Gan
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p. 3511 - 3517
(2019/08/12)
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- Aerobic Homocoupling of Arylboronic Acids Catalyzed by Regenerable Pd(II)@MIL-88B-NH2(Cr)
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A fast and operationally simple method for the aerobic homocoupling of arylboronic acids is described. The process is catalyzed by Pd(II) complexes supported on the metal-organic framework MIL-88B-NH2(Cr). The benefits of this approach include the use of a benign oxidant/solvent mixture at room temperature with catalytic amounts of base, easy recovery of the catalyst, and easy isolation of the products. Very high conversions and good yields were achieved for a variety of substrates, and the process was also carried out on a larger scale with the same efficiency. The catalyst was found to suffer deactivation due to progressive reduction and agglomeration of palladium into inactive metal clusters/particles. An innovative procedure for the oxidative redispersion and regeneration of the active Pd(II)@MOF species is presented.
- Valiente, Alejandro,Carrasco, Sergio,Sanz-Marco, Amparo,Tai, Cheuk-Wai,Bermejo Gómez, Antonio,Martín-Matute, Belén
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p. 3933 - 3940
(2019/05/22)
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- Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki-Miyaura Reactions of Aryl Carbonates
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Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles in cross-coupling reactions. Here, after performing a thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki-Miyaura reactions using a variety of aryl carbonates as substrates. Mechanistic studies indicate that (dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(0) active species and (ii) it minimizes comproportionation reactions between the Ni(0) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I) species. In contrast, the state of the art precatalyst (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1-bis(diphenylphosphino)ferrocene), which contains a bidentate phosphine that binds in a cis geometry, forms Ni(I) species during activation and is essentially inactive for aryl carbonate couplings. Although the exact reasons on a molecular level why the dcypf system is more active than the dppf system are unclear, our results indicate that in general Ni catalysts supported by the dcypf ligand will give better performance for catalytic reactions involving substrates which undergo relatively slow oxidative addition, such as aryl carbonates.
- Barth, Emily L.,Davis, Ryan M.,Mohadjer Beromi, Megan,Walden, Andrew G.,Balcells, David,Brudvig, Gary W.,Dardir, Amira H.,Hazari, Nilay,Lant, Hannah M. C.,Mercado, Brandon Q.,Peczak, Ian L.
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supporting information
p. 3377 - 3387
(2019/09/30)
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- Nickel/copper-cocatalyzed decarbonylative silylation of acyl fluorides
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Ni/Cu-cocatalyzed decarbonylative silylation of acyl fluorides with silylboranes has been developed to afford various arylsilanes with high efficiency and good functional-group compatibility via carbon-fluorine bond cleavage and carbon-silicon bond formation. Such transformation can not only extend the functionalization type of acyl fluorides but complement the synthetic route for arylsilanes.
- Wang, Xiu,Wang, Zhenhua,Nishihara, Yasushi
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supporting information
p. 10507 - 10510
(2019/09/06)
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- Desulfurization of Diaryl(heteroaryl) Sulfoxides with Benzyne
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Two benzyne-enabled desulfurization reactions have been demonstrated which convert diaryl sulfoxides and heteroaryl sulfoxides to biaryls and desulfurized heteroarenes, respectively. The reaction accessing biaryls tolerates a variety of functional groups, such as halides, pseudohalides, and carbonyls. Mechanistic studies reveal that both reactions proceed via a common assembly process but divergent disassemblies of the generated tetraaryl(heteroaryl) sulfuranes.
- Chen, De-Li,Sun, Yan,Chen, Mengyuan,Li, Xiaojin,Zhang, Lei,Huang, Xin,Bai, Yihui,Luo, Fang,Peng, Bo
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supporting information
(2019/06/13)
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- Heterogeneous Nickel-Catalyzed Cross-Coupling between Aryl Chlorides and Alkyllithiums Using a Polystyrene-Cross-Linking Bisphosphine Ligand
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A polystyrene-cross-linking bisphosphine ligand PS-DPPBz was used for Ni-catalyzed cross-coupling with organolithiums. A bench-stable precatalyst [NiCl2(PS-DPPBz)] enabled efficient coupling reactions between aryl chlorides and alkyllithiums. The heterogeneous Ni system showed good reusability. (Figure presented.).
- Yamazaki, Yuki,Arima, Nozomi,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 2250 - 2254
(2019/03/21)
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- Palladium (II)-Catalyzed Decarboxylative Cross-Dehydrogenative Coupling: Direct Synthesis of meta-Substituted Biaryls from Aromatic Acids
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A palladium-catalyzed tandem process of simple aromatic acids has been achieved to afford meta-substituted biaryls in moderate to good yields. The reaction proceeds via carboxyl-directed intermolecular cross-dehydrogenative coupling and subsequent decarboxylation. The new C?C bonds in this transformation are formed in the ortho position of carboxyl and the reaction tolerates electron-rich acids. Both symmetrical and unsymmetrical meta-substituted biaryls can be directly synthesized via this method. (Figure presented.).
- Pu, Fan,Zhang, Lin-Yan,Liu, Zhong-Wen,Shi, Xian-Ying
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supporting information
p. 2644 - 2649
(2018/07/29)
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- Nickel-Catalyzed Heteroarenes Cross Coupling via Tandem C-H/C-O Activation
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Inert aryl methyl ethers as coupling components via C-O activation have been established with a Ni catalyst for C-H activation of heteroarene. The key to simultaneous C-H/C-O bond activation is the use of sterically demanding o-tolylMgBr. The protocol is effective for a wide scope of substrates including naphthyl methyl ethers, anisoles, and a variety of other heteroarene derivatives. Detailed mechanistic studies indicated that the C-O cleavage is assisted via synergistic effect of nickel and Grignard reagent in this C-H/C-O reaction, which is supported by DFT calculation. At this stage, single-electron transfer can be ruled out as a main operative process for this tandem strategy.
- Wang, Ting-Hsuan,Ambre, Ram,Wang, Qing,Lee, Wei-Chih,Wang, Pen-Cheng,Liu, Yuhua,Zhao, Lili,Ong, Tiow-Gan
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p. 11368 - 11376
(2018/11/23)
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- Intramolecular Desulfitative Coupling: Nickel-Catalyzed Transformation of Diaryl Sulfones into Biaryls via Extrusion of SO2
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As a new transformation of organosulfur compounds, intramolecular desulfitative coupling of diaryl sulfones to the corresponding biaryls has been developed with the aid of nickel-NHC catalysts. This catalytic elimination of SO2 was also applicable to alkenyl aryl sulfone to furnish the corresponding alkenyl arene.
- Takahashi, Fumiya,Nogi, Keisuke,Yorimitsu, Hideki
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supporting information
p. 6601 - 6605
(2018/10/20)
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- An Active Palladium Colloidal Catalyst for the Selective Oxidative Heterocoupling of (Hetero)Aryl Boronic Acids
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A highly selective oxidative heterocoupling protocol for (hetero)aryl boronic acids with an active palladium colloidal catalyst was developed. The judicious choice of electronically different aryl boronic acids made possible such couplings under mild conditions, with air as oxidant, while embracing a wide substrate scope. This successful approach further allowed the development of a unique one-pot sequential oxidative heterocoupling/Suzuki–Miyaura cross-coupling tandem process for accessing substituted terphenyls.
- Sable, Vaibhav,Maindan, Karan,Bhilare, Shatrughn,Chrysochos, Nicolas,Schulzke, Carola,Kapdi, Anant R.
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supporting information
p. 2489 - 2498
(2018/09/10)
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- Palladium-Catalyzed Regio- and Stereoselective Coupling-Addition of Propiolates with Arylsulfonyl Hydrazides: A Pattern for Difunctionalization of Alkynes
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A new pattern for difunctionalization of alkynes via a palladium-catalyzed regio- and stereoselective coupling-addition of propiolates with arylsulfonyl hydrazides is disclosed. The approach enables the synthesis of various highly functionalized (E)-vinylsulfones in satisfactory yields. Arylsulfonyl hydrazides act as both aryl and sulfonyl sources via selective cleavage of Ar(C)-S and S-N bonds, which are simultaneously incorporated onto the terminal carbon atom of an alkyne molecule.
- Liu, Lixin,Sun, Kang,Su, Lebin,Dong, Jianyu,Cheng, Lei,Zhu, Xiaodong,Au, Chak-Tong,Zhou, Yongbo,Yin, Shuang-Feng
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supporting information
p. 4023 - 4027
(2018/07/15)
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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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- Palladium-Catalysed Cross-Coupling of Benzylammonium Salts with Boronic Acids under Mild Conditions
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Herein, we give a full account of the development of the palladium-catalysed cross-coupling of benzylammonium salts with boronic acids. A range of benzylamine-derived quaternary ammonium salts can be coupled with boronic acids under relatively mild conditions. Our optimization has identified ligands that can be used to chemoselectively cross-couple at the ammonium in the presence of chlorides. We demonstrate that intramolecular palladium-catalysed C-H activation is also a viable pathway for the putative benzyl-Pd(II) intermediate obtained upon oxidative addition and have optimised this to obtain fluorene in good yield.
- Türtscher, Paul L.,Davis, Holly J.,Phipps, Robert J.
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p. 793 - 803
(2017/10/07)
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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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- Synthesis, characterization and reactivity of vanadium, chromium, and manganese PNP pincer complexes
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The synthesis of a series of vanadium, chromium, and manganese PNP complexes of the types [M(PNP)Cl3] (M = V, Cr) and [M(PNP)Cl2] (M = Cr, Mn) is reported. Vanadium and manganese PNP pincer complexes are described for the first time. All complexes are characterized by their magnetic moments, elemental analysis, and ESI MS. In addition, some compounds are characterized by X-ray crystallography. In a preliminary study, these complexes catalyze the oxidative homo-coupling of aryl Grignard reagents in the presence of MeI as oxidizing agents to give symmetrical biaryls, but are inactive in Kumada cross-coupling reactions. The reactivity of V(III), Cr(III), Cr(II) and Mn(II) is compared with related Fe(II) and Co(II) complexes of the types [Fe(PNP-iPr)Cl2], and [Co(PNP-iPr)Cl2]. In all cases, good to excellent isolated yields are obtained. However, since the respective metal chlorides in the absence of PNP ligands exhibited comparable reactivities, the new PNP complexes offer no real advantage for this type of coupling reactions.
- Mastalir, Matthias,Glatz, Mathias,St?ger, Berthold,Weil, Matthias,Pittenauer, Ernst,Allmaier, Günter,Kirchner, Karl
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p. 707 - 714
(2016/12/02)
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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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- Oxidative Addition of Aryl Electrophiles to a Prototypical Nickel(0) Complex: Mechanism and Structure/Reactivity Relationships
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Detailed kinetic studies of the reaction of a model Ni0 complex with a range of aryl electrophiles have been conducted. The reactions proceed via a fast ligand exchange pre-equilibrium, followed by oxidative addition to produce either [NiIX(dppf)] (and biaryl) or [NiII(Ar)X(dppf)]; the ortho substituent of the aryl halide determines selectivity between these possibilities. A reactivity scale is presented in which a range of substrates is quantitatively ranked in order of the rate at which they undergo oxidative addition. The rate of oxidative addition is loosely correlated to conversion in prototypical cross-coupling reactions. Substrates that lead to NiI products in kinetic experiments produce more homocoupling products under catalytic conditions.
- Bajo, Sonia,Laidlaw, Gillian,Kennedy, Alan R.,Sproules, Stephen,Nelson, David J.
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supporting information
p. 1662 - 1672
(2017/04/28)
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- Nickel-mediated decarbonylation of simple unstrained ketones through the cleavage of carbon-carbon bonds
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Despite advances in methods for the decarbonylation of aldehydes, the decarbonylation of ketones has been met with limited success because this process requires the activation of two inert carbon-carbon bonds. All of the decarbonylation reactions of simple unstrained ketones reported to date require the addition of a stoichiometric rhodium complex. We report herein the nickel/N-heterocyclic carbene-mediated decarbonylation of simple diaryl ketones. This reaction shows unique acceleration effects based on the presence of both electron-donating and electron-withdrawing groups.
- Morioka, Toshifumi,Nishizawa, Akihiro,Furukawa, Takayuki,Tobisu, Mamoru,Chatani, Naoto
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supporting information
p. 1416 - 1419
(2017/02/10)
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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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- 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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- Aryl Ketones as Single-Electron-Transfer Photoredox Catalysts in the Nickel-Catalyzed Homocoupling of Aryl Halides
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An intriguing photoredox system for the homocoupling of aryl halides is reported wherein thioxanthone catalyzes a single-electron transfer from an amine reductant to nickel.
- Masuda, Yusuke,Ishida, Naoki,Murakami, Masahiro
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supporting information
p. 5822 - 5825
(2016/12/18)
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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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- 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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- Quinonediimines as redox-active organocatalysts for oxidative coupling of aryl- and alkenylmagnesium compounds under molecular oxygen
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It is revealed that N,N′-diphenyl-p-benzoquinonediimine works as a redox-active organocatalyst for the oxidative homo-coupling of aryl- and alkenylmagnesium compounds under molecular oxygen. The catalytic cycle was formally monitored by 1H NMR experiments.
- Amaya, Toru,Suzuki, Riyo,Hirao, Toshikazu
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p. 7790 - 7793
(2016/07/06)
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- C-O/C-H Coupling of Polyfluoroarenes with Aryl Carbamates by Cooperative Ni/Cu Catalysis
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Cross-coupling of polyfluoroarenes with aryl carbamates through the cleavage of both sp2 C-O and C-H bonds is reported. The reaction conditions are simple, and only transition-metal catalysts and ligands are essential. Mechanistic studies indicated that Ni catalyst played an important role in activating C-O bond, while the Cu one in activating C-H Bond. The developed system proved to be effective for cross-coupling of terminal alkynes with aryl carbamates.
- Wang, Yang,Wu, Song-Bai,Shi, Wen-Juan,Shi, Zhang-Jie
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supporting information
p. 2548 - 2551
(2016/07/06)
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- Nickel-Catalyzed Cross-Coupling of Organolithium Reagents with (Hetero)Aryl Electrophiles
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Nickel-catalyzed selective cross-coupling of aromatic electrophiles (bromides, chlorides, fluorides and methyl ethers) with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene (NHC) complex allows the reaction with a variety of (hetero)aryllithium compounds, including those prepared via metal-halogen exchange or direct metallation, whereas a commercially available electron-rich nickel-bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product. These reactions proceed rapidly (1 h) under mild conditions (room temperature) while avoiding the undesired formation of reduced or homocoupled products. Nickel-catalyzed cross-coupling of aromatic electrophiles with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene complex allows reaction with a variety of (hetero)aryllithium compounds, whereas a commercially available electron-rich nickel bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product.
- Heijnen, Dorus,Gualtierotti, Jean-Baptiste,Hornillos, Valentín,Feringa, Ben L.
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supporting information
p. 3991 - 3995
(2016/03/16)
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- A method of compounding aromatic hydrazine synthesis symmetry biphenyl
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The invention discloses a method for synthesizing symmetrical biphenyl from aromatic hydrazine, which belongs to the field of organic synthesis. The method comprises the following steps: separately adding the aromatic hydrazine, inorganic base and a palladium catalyst into a reaction tube filled with a proper amount of a solvent, wherein the mol ratio of the aromatic hydrazine to the inorganic base to the palladium catalyst is 50: 50: 1; carrying out heating to 50 DEG C and magnetic stirring for 3 h; after completion of a reaction, carrying out cooling to room temperature; and then carrying out filtering, subjecting the solvent to spinning drying and carrying out recrystallization so as to obtain the symmetrical biphenyl. According to the method, reactive denitrification groups are removed in the form of nitrogen, which is green and free of pollution; the reaction takes air as an oxidation agent to promote oxidation denitrification, does not need any gas protection, and can be performed very well in the air without producing any by-product; and symmetrical biphenyl compounds can be prepared from cheap and easily-available aromatic hydrazine, so the method has high practicability and selectivity, and the product yield is normally much higher than the product yield reported in the literature.
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Paragraph 0034-0036
(2018/01/14)
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- Comparison of dppf-Supported Nickel Precatalysts for the Suzuki-Miyaura Reaction: The Observation and Activity of Nickel(I)
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Ni-based precatalysts for the Suzuki-Miyaura reaction have potential chemical and economic advantages compared to commonly used Pd systems. Here, we compare Ni precatalysts for the Suzuki-Miyaura reaction supported by the dppf ligand in 3 oxidation states, 0, I and II. Surprisingly, at 80 °C they give similar catalytic activity, with all systems generating significant amounts of NiI during the reaction. At room temperature a readily accessible bench-stable NiII precatalyst is highly active and can couple synthetically important heterocyclic substrates. Our work conclusively establishes that NiI species are relevant in reactions typically proposed to involve exclusively Ni0 and NiII complexes.
- Guard, Louise M.,Mohadjer Beromi, Megan,Brudvig, Gary W.,Hazari, Nilay,Vinyard, David J.
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supporting information
p. 13352 - 13356
(2015/11/09)
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- Efficient phosphine ligands for the one-pot palladium-catalyzed borylation/Suzuki-Miyaura cross-coupling reaction
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We report the synthesis of 2-(anthracen-9-yl)-1H-inden-3-yl dicyclohexylphosphine and its use in palladium-catalyzed borylation/Suzuki-Miyaura cross-coupling reaction to prepare a variety of symmetrical and unsymmetrical biaryl compounds in excellent yield. This journal is
- Chen, You,Peng, Hui,Pi, Yun-Xiao,Meng, Tong,Lian, Ze-Yu,Yan, Meng-Qi,Liu, Yan,Liu, Sheng-Hua,Yu, Guang-Ao
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supporting information
p. 3236 - 3242
(2015/03/18)
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