- Ir-Catalyzed Remote Functionalization by the Combination of Deconjugative Chain-Walking and C-H Activation Using a Transient Directing Group
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An Ir-catalyzed reaction of N-benzylideneanilines with functionalized alkenes such as α,β-unsaturated esters gave ortho-substituted benzaldehyde derivatives with a functional group at the remote position after acidic treatment. The present transformation
- Tang, King Hung Nigel,Uchida, Kanako,Nishihara, Kazuki,Ito, Mamoru,Shibata, Takanori
-
supporting information
p. 1313 - 1317
(2022/02/23)
-
- Dinuclear cobalt complex-catalyzed stereodivergent semireduction of alkynes: Switchable selectivities controlled by H2O
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Catalytic semireduction of internal alkynes to alkenes is very important for organic synthesis. Although great success has been achieved in this area, switchable Z/E stereoselectivity based on a single catalyst for the semireduction of internal alkynes is a longstanding challenge due to the multichemo- and stereoselectivity, especially based on less-expensive earth-abundant metals. Herein, we describe a switchable semireduction of alkynes to (Z)- or (E)-alkenes catalyzed by a dinuclear cobalt complex supported by a macrocyclic bis pyridyl diimine (PDI) ligand. It was found that cis-reduction of the alkyne occurs first and the Z-E alkene stereoisomerization process is formally controlled by the amount of H2O, since the concentration of H2O may influence the catalytic activity of the catalyst for isomerization. Therefore, this protocol provides a facile way to switch to either the (Z)- or (E)-olefin isomer in a single transformation by adjusting the amount of water.
- Chen, Ke,Zhu, Hongdan,Li, Yuling,Peng, Qian,Guo, Yinlong,Wang, Xiaoming
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p. 13696 - 13705
(2021/11/16)
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- METHODS OF BORYLATION AND USES THEREOF
-
The present invention relates, in general terms, to methods of borylation and uses thereof. In particular, the present invention provides a method of borylating an alkene compound by contacting the compound with a boron compound, a Fe pre-catalyst and a protic additive. The borylation occurs at a vicinal (β) position to an electron donating or electron withdrawing moiety of the compound.
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Page/Page column 63
(2021/04/30)
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- Recyclable and reusable PdCl2(PPh3)2/PEG-400/H2O system for the hydrophenylation of alkynes with sodium tetraphenylborate
-
A stable and efficient PdCl2(PPh3)2/PEG-400/H2O catalytic system for the hydrophenylation reaction of alkynes has been developed. In the presence of 3 mol% PdCl2(PPh3)2 and 2 equiv. of HOAc, the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate proceeded smoothly in a mixture of PEG-400 and water at room temperature or 50 °C to afford a variety of phenyl-substituted alkenes in moderate to high yields. The isolation of the products was easily performed by extraction with petroleum ether, and the PdCl2(PPh3)2/PEG-400/H2O system could be readily recycled and reused six times without apparent loss of catalytic activity.
- Liu, Rong,Zhang, Tingli,Huang, Bin,Cai, Mingzhong
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p. 172 - 178
(2020/07/04)
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- Selective hydroboration of equilibrating allylic azides
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The iridium(i)-catalyzed hydroboration of equilibrating allylic azides is reported to provide only the anti-Markovnikov product of alk-1-ene isomers in good yields and with good functional group tolerance.
- Liu, Ruzhang,Xu, Jun,Zhang, Yuanyuan
-
supporting information
p. 8913 - 8916
(2021/09/13)
-
- Efficient in situ palladium nano catalysis for Z-selective semi transfer hydrogenation of internal alkynes using safer 1, 4-butanediol
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Simple and efficient in situ generated palladium nanoparticles (PdNPs) in PEG-4OO catalyzed semi transfer hydrogenation of internal alkynes to Z-alkenes with excellent selectivity along with the formation of beneficial γ-butyrolactone as a byproduct using low quantity of safer and attractive 1, 4-butanediol as a hydrogen source was described.
- Rapeti, Siva Kumar,Kasina, Krishna Chaitanya,Gundepaka, Prasad,Birudaraju, Saritha,Sailaja
-
supporting information
(2019/12/09)
-
- Stereoselective Chromium-Catalyzed Semi-Hydrogenation of Alkynes
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Chromium complexes have found very little applications as hydrogenation catalysts. Here, we report a Cr-catalyzed semi-hydrogenation of internal alkynes to the corresponding Z-alkenes with good stereocontrol (up to 99/1 for dialkyl alkynes). The catalyst comprises the commercial reagents chromium(III) acetylacetonate, Cr(acac)3, and diisobutylaluminium hydride, DIBAL?H, in THF. The semi-hydrogenation operates at mild conditions (1-5 bar H2, 30 °C).
- Gregori, Bernhard J.,Nowakowski, Michal,Schoch, Anke,P?llath, Simon,Zweck, Josef,Bauer, Matthias,Jacobi von Wangelin, Axel
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p. 5359 - 5363
(2020/09/03)
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- ISOMERIZATION OF ALKENES
-
The present invention relates to an isomerization method for alkenes, comprising of reaction an alkene with a Ni(I)-compound. By this method, E-Alkenes are obtained in excellent yield.
- -
-
Page/Page column 20-21; 25
(2020/04/25)
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- Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
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Migratory functionalization of alkenes has emerged as a powerful strategy to achieve functionalization at a distal position to the original reactive site on a hydrocarbon chain. However, an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminal alkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminal alkynes and cobalt-catalyzed hydrogenation of either 2-alkynes or conjugated diene intermediates. Notably, this practical non-noble metal catalytic system enables efficient control of the chemo-, regio-, and stereoselectivity of this transformation.
- Liu, Bingxue,Liu, Qiang,Liu, Xufang
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p. 6750 - 6755
(2020/03/13)
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- Cobalt-Catalyzed Migrational Isomerization of Styrenes
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An efficient cobalt-catalyzed migrational isomerization of styrenes was developed using the thiazoline iminopyridine (TIP) ligand. This reaction is operationally simple and atom-economical using readily available starting materials to access trisubstituted alkenes. Even when using a 0.1 mol % catalyst loading, the reaction could be conducted in neat and completed in 1 h with excellent conversion and high E stereoselectivity.
- Zhao, Jiajin,Cheng, Biao,Chen, Chenhui,Lu, Zhan
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p. 837 - 841
(2020/01/31)
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- Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
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The catalytic isomerization of C-C double bonds is an indispensable chemical transformation used to deliver higher-value analogues and has important utility in the chemical industry. Notwithstanding the advances reported in this field, there is compelling demand for a general catalytic solution that enables precise control of the C═C bond migration position, in both cyclic and acyclic systems, to furnish disubstituted and trisubstituted alkenes. Here, we show that catalytic amounts of an appropriate earth-abundant iron-based complex, a base and a boryl compound, promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from one substrate can be facilitated, isomeric olefin mixtures commonly found in petroleum-derived feedstock can be transformed to a single alkene product, and unsaturated moieties embedded within linear and heterocyclic biologically active entities can be obtained.
- Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
-
supporting information
p. 18223 - 18230
(2020/12/04)
-
- An Annelated Mesoionic Carbene (MIC) Based Ru(II) Catalyst for Chemo- And Stereoselective Semihydrogenation of Internal and Terminal Alkynes
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The catalytic utility of [RuL1(CO)2I2] (1), containing an annelated π-conjugated imidazo-naphthyridine-based mesoionic carbene (MIC) ligand (L1), is evaluated for E-selective alkyne semihydrogenation. The precatalyst 1, in combination with 2 equiv of AgBArF, semihydrogenates a broad range of internal alkynes with molecular hydrogen (5 bar) in water. (E)-Alkenes are accessed in high yields, and a number of reducible functional groups are tolerated. A chelate MIC ligand and two cis carbonyls provide a well-defined platform at the Ru center for hydrogenation and isomerization. The loss of two iodides and the presence of two carbonyls render the Ru center electron deficient and thus the formation of metal vinylidenes with terminal alkynes is avoided. This is leveraged for the semihydrogenation of terminal alkynes by the same catalytic system in isopropyl alcohol. Reaction profile, isomerization, kinetic, and DFT studies reveal initial alkyne hydrogenation to a (Z)-alkene, which further isomerizes to an (E)-alkene via metal-catalyzed Z → E isomerization.
- Bera, Jitendra K.,Choudhury, Joyanta,Das, Shubhajit,Dutta, Indranil,Pati, Swapan K.,Saha, Sayantani,Yadav, Suman
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p. 3212 - 3223
(2020/10/02)
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- Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst
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The stereoselective hydrogenation of alkynes constitutes one of the key approaches for the construction of stereodefined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. This study concerns a simple catalyst comprised of the commercial chemicals iron(II) acetylacetonate and diisobutylaluminum hydride, which enables the Z-selective semihydrogenation of alkynes under near ambient conditions (1–3 bar H2, 30 °C, 5 mol % [Fe]). Neither an elaborate catalyst preparation nor addition of ligands is required. Mechanistic studies (kinetic poisoning, X-ray absorption spectroscopy, TEM) strongly indicate the operation of small iron clusters and particle catalysts.
- Gregori, Bernhard J.,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Fritsch, Lorena,Schoch, Roland,Bauer, Matthias,Jacobi von Wangelin, Axel
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p. 3864 - 3870
(2019/07/31)
-
- 1-Methyl-1H-tetrazol-5-yl (MT) sulfones in the Julia-Kocienski olefination: Comparison with the PT and the TBT sulfones
-
The stability and the stereoselectivity of newly prepared n-pentyl 1-methyl-1H-tetrazol-5-yl (MT) sulfone 1a in the Julia-Kocienski reactions were compared with those of the PT sulfone 1b and the TBT sulfone 1c. The improved stability of the anion derived from the n-pentyl MT sulfone 1a enhanced the efficiency of the olefination reactions and gave higher yields of the product alkenes 3 compared with the PT sulfone 1b. Especially high E-selectivity and high yields were obtained from the reaction with aromatic aldehydes and α,β-unsaturated aldehydes. The selectivity of 1a was not so sensitive to the change of base counter ion compared with the PT sulfone 1b. The reaction of the MT sulfones having either ethyl or a longer alkyl chain also gave E-alkenes selectively in high yields.
- Ando, Kaori,Kawano, Daiki,Takama, Daiki,Semii, Yutaka
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p. 1566 - 1569
(2019/05/22)
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- Mechanochemical Oxidative Heck Coupling of Activated and Unactivated Alkenes: A Chemo-, Regio- and Stereo-Controlled Synthesis of Alkenylbenzenes
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In this work, we present an efficient mechanochemical strategy for chemo-, regio- and stereo-selective oxidative Heck coupling of readily accessible arylboron reagents/heteroaromatics with cyclic and acyclic olefins. Mono- and bis-arylation were achieved without the need of ligands, directing groups or prefunctionalized alkenes, and the reaction chemo-selectivity could be controlled by tuning of the oxidative system. This protocol offers the synthesis of alkenylbenzenes in broad substrate scope, satisfactory yields and excellent selectivity even in the gram scale. (Figure presented.).
- Yu, Jingbo,Shou, Haowen,Yu, Wangyang,Chen, Haodong,Su, Weike
-
supporting information
p. 5133 - 5139
(2019/11/11)
-
- Preparation method of inactive alkene aryl compound
-
The invention discloses a preparation method of an inactive alkene aryl compound. The preparation method comprises steps as follows: arylboronic acid and inactive alkene are taken as raw materials andsubjected to an oxidization Heck reaction with a mechan
- -
-
Paragraph 0083; 0084
(2019/06/05)
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- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
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We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
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p. 5723 - 5728
(2019/04/03)
-
- E-Olefins through intramolecular radical relocation
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Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
- Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
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p. 391 - 396
(2019/02/03)
-
- Stereospecific Iron-Catalyzed Carbon(sp2)-Carbon(sp3) Cross-Coupling with Alkyllithium and Alkenyl Iodides
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An efficient synthetic protocol involving iron-catalyzed cross-coupling reactions between organolithium compounds and alkenyl iodides as key coupling partners was achieved. More than 30 examples were obtained with moderate to good yields and high stereospecificity. Gram-scale and synthetic applications of this procedure are recorded herein to demonstrate its feasibility and potential utilization.
- Lu, Xiao-Lin,Shannon, Mark,Peng, Xiao-Shui,Wong, Henry N. C.
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p. 2546 - 2549
(2019/03/26)
-
- Gram-Scale, Cheap, and Eco-Friendly Iron-Catalyzed Cross-Coupling between Alkyl Grignard Reagents and Alkenyl or Aryl Halides
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A new robust methodology for gram-scale iron-catalyzed cross-coupling between alkyl Grignard reagents and alkenyl or aryl halides is developed. This method does not require toxic additives such as NMP or expensive ligands. Its efficiency relies on the use of simple alkoxide magnesium salts as additives. On the basis of these results, a new procedure for one-pot synthesis of substituted benzamides from chloroesters is also proposed.
- Cahiez, Gérard,Lefèvre, Guillaume,Moyeux, Alban,Guerret, Olivier,Gayon, Eric,Guillonneau, Lo?c,Lefèvre, Nicolas,Gu, Qinzhuo,Zhou, Edouard
-
supporting information
p. 2679 - 2683
(2019/04/30)
-
- P-Chiral Monophosphorus Ligands for Asymmetric Copper-Catalyzed Allylic Alkylation
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Asymmetric copper-catalyzed allylic alkylation between allyl bromides and alkyl Grignard reagents using a P-chiral monophosphorus ligand is described. A range of terminal olefins bearing tertiary or quaternary carbon centers were formed in good branched/linear selectivities and excellent enantioselectivities at copper loadings as low as 0.5 mol %.
- Xiong, Wenrui,Xu, Guangqing,Yu, Xinhong,Tang, Wenjun
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p. 4003 - 4013
(2019/06/24)
-
- Palladium-catalyzed Mizoroki-Heck reactions in water using thermoresponsive polymer micelles
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Palladium-catalyzed Mizoroki-Heck reactions were carried out in water using thermoresponsive polymer micelles. The micelles were generated from thermoresponsive block copolymers consisting of a poly(N-isopropylacrylamide) (PNIPAAm) segment and a hydrophilic segment such as nonionic poly(ethylene glycol) (PEG) (2) and anionic poly(sodium p-styrenesulfonate) (PSSNa) (9). These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 40–50 °C and showed thermal stimuli-induced formation and dissociation of micelles. The copolymers formed micelles in aqueous solution at higher temperature, where catalytic reactions proceeded. At lower temperature, the micelles dissociated to form a clear solution, enabling efficient extraction of the products from aqueous reaction mixture. In the presence of these copolymers, palladium complexes catalyzed the coupling reactions between aryl iodides and alkene compounds inside the hydrophobic micelle cores in water under relatively milder conditions. Extraction of the products from the aqueous solution of 2 or 9 was found to be efficient enough in comparison with conventional surfactants.
- Suzuki, Noriyuki,Takabe, Taiga,Yamauchi, Yoshiko,Koyama, Shun,Koike, Rina,Rikukawa, Masahiro,Liao, Wei-Ting,Peng, Wen-Sheng,Tsai, Fu-Yu
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p. 1351 - 1358
(2019/02/06)
-
- Bis(bipyridine) ruthenium(ii) bis(phosphido) metalloligand: Synthesis of heterometallic complexes and application to catalytic (E)-selective alkyne semi-hydrogenation
-
The first phosphido derivative of the bis(bipyridine) ruthenium(ii) fragment, cis-[(bpy)2Ru(PPh2)2] ([RuP2]), has been developed and applied as a P-donor metalloligand to form new Ru-Rh, Ru-Ir and Ru2Cu2 heterometallic complexes. The Ru-Ir hydride complex [([RuP2])IrH(NCMe)3][BF4]2 exhibits significant catalytic activity for (E)-selective semi-hydrogenation of alkynes.
- Takemoto, Shin,Kitamura, Manami,Saruwatari, Shuhei,Isono, Atsutaka,Takada, Yoko,Nishimori, Rie,Tsujiwaki, Mina,Sakaue, Naoki,Matsuzaka, Hiroyuki
-
supporting information
p. 1161 - 1165
(2019/01/28)
-
- Visible photocatalysis of novel oxime phosphonates: Synthesis of β-aminophosphonates
-
A novel type of oxime phosphonate was synthesized and used in the intermolecular cascade radical addition reaction of alkenes to access β-aminophosphonates via visible-light-driven N-centered iminyl radical-mediated and redox-neutral selective C-P single-bond cleavage in an active phosphorus radical route. The procedure is characterized by its ability to achieve the construction of Csp3-P and Csp3-N bonds without the requirement for oxidants and bases.
- Li, Yong-Hong,Wang, Chun-Hai,Gao, Su-Qian,Qi, Feng-Ming,Yang, Shang-Dong
-
supporting information
p. 11888 - 11891
(2019/10/11)
-
- Phosphine-free cobalt pincer complex catalyzed: Z -selective semi-hydrogenation of unbiased alkynes
-
Herein, we report a novel, molecularly defined NNN-type cobalt pincer complex catalyzed transfer semi-hydrogenation of unbiased alkynes to Z-selective alkenes. This unified process is highly stereo- and chemo-selective and exhibits a broad scope as well as wide functional group tolerance. Ammonia-borane (AB), a bench-stable substrate with high gravimetric hydrogen capacity, was used as a safe and practical transfer hydrogenating source.
- Landge, Vinod G.,Pitchaimani, Jayaraman,Midya, Siba P.,Subaramanian, Murugan,Madhu, Vedichi,Balaraman, Ekambaram
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p. 428 - 433
(2018/02/07)
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- Stereoselective Transfer Semi-Hydrogenation of Alkynes to E-Olefins with N-Heterocyclic Silylene–Manganese Catalysts
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The synthesis and structures of the first SiII-donor supported manganese(II) complexes [L1]MnCl2, [L2]MnCl2, and [L3]2MnCl2 are reported, bearing a pincer-type bis(NHSi)-pyridine ligand L1, bidentate bis(NHSi)-ferrocene ligand L2, and two monodentate NHSi ligands L3 (NHSi = N-heterocyclic silylene), respectively. They act as unprecedented very active and stereoselective Mn-based precatalysts (1 mol % loading) in transfer semi-hydrogenations of alkynes to give the corresponding E-olefins using ammonia–borane as a convenient hydrogen source under mild reaction conditions. Complex [L1]MnCl2 shows the best catalytic performance with quantitative conversion rates and excellent E-stereoselectivities (up to 98 %) for different alkyne substrates. Different types of functional groups can be tolerated, except CN, NH2, NO2, and OH groups at the phenyl group of 1-phenyl substituted alkynes.
- Zhou, Yu-Peng,Mo, Zhenbo,Luecke, Marcel-Philip,Driess, Matthias
-
supporting information
p. 4780 - 4784
(2017/12/26)
-
- Decarboxylative olefination of potassium benzoates via bimetallic catalysis strategy
-
Abstract: A novel synthesis of styrene derivatives through decaroxylative olefination of potassium benzoates with alkynes using Pd2dba3/CuBr as catalyst system has been developed. The protocol proceeded smoothly and in most cases Z-alkene was the main product. Electron-rich potassium benzoates reacted more efficiently than those of electron-deficient substrates. Heteroaromatic and electron-deficient aryl alkynes were not consistent with this transformation. Graphical abstract: [Figure not available: see fulltext.].
- Khalaj, Mehdi,Ghazanfarpour-Darjani, Majid,Taheri, Saeed,Sedaghat, Sajjad,Hoseyni, Seyed Jalal
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p. 2013 - 2019
(2018/09/25)
-
- Metal-Catalyzed Remote Functionalization of ω-Ene Unsaturated Ethers: Towards Functionalized Vinyl Species
-
The combined ruthenium-catalyzed chain walking with the nickel-catalyzed cross-coupling reaction of ω-alkenyl ethers provide a unique entry to functionalized vinyl species. This transformation illustrates the power and flexibility of remote functionalization by demonstrating the compatibility of two independent reactions involving unrelated sites.
- Ho, Guo-Ming,Judkele, Lina,Bruffaerts, Jeffrey,Marek, Ilan
-
supporting information
p. 8012 - 8016
(2018/06/29)
-
- Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
-
We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
- La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
-
supporting information
p. 7438 - 7446
(2018/05/29)
-
- An N-heterocyclic carbene ligand promotes highly selective alkyne semihydrogenation with copper nanoparticles supported on passivated silica
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We report a surface organometallic route that generates copper nanoparticles (NPs) on a silica support while simultaneously passivating the silica surface with trimethylsiloxy groups. The material is active for the catalytic semihydrogenation of phenylalkyl-, dialkyl- and diaryl-alkynes and displays high chemo- and stereoselectivity at full alkyne conversion to corresponding (Z)-olefins in the presence of an N-heterocyclic carbene (NHC) ligand. Solid-state NMR spectroscopy using the NHC ligand 13C-labeled at the carbenic carbon reveals a genuine coordination of the carbene to Cu NPs. The presence of distinct Cu surface environments and the coordination of the NHC to specific Cu sites likely account for the increased selectivity.
- Kaeffer, Nicolas,Liu, Hsueh-Ju,Lo, Hung-Kun,Fedorov, Alexey,Copéret, Christophe
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p. 5366 - 5371
(2018/06/27)
-
- An Interrupted Pummerer/Nickel-Catalysed Cross-Coupling Sequence
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An interrupted Pummerer/nickel-catalysed cross-coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one-pot process, involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp-, sp2-, and sp3-hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo- and heterocyclic alkenyl sulfonium salts for cross-coupling.
- Aukland, Miles H.,Talbot, Fabien J. T.,Fernández-Salas, José A.,Ball, Matthew,Pulis, Alexander P.,Procter, David J.
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p. 9785 - 9789
(2018/07/31)
-
- Controlled hydrogenation of diphenylacetylene using alkylammonium formate
-
A simple and straightforward semihydrogenation of alkyne to alkene with triethanolamine and formic acid in the presence of PdCl2 has been described. Although hydrogenation using formic acid as a hydrogenation source has been used in combination with amines previously, few reports are available concerning the associated reactivity. We demonstrated that reactivity changes depending on the type of amine used in the hydrogenation. Further, this reaction requires no strict time control, making it a useful tool in organic synthesis.
- Suzuki, Hideyuki,Satoh, Ikkyu,Nishioka, Hiromi,Takeuchi, Yasuo
-
supporting information
p. 3834 - 3837
(2017/09/15)
-
- Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
-
Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
- Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
-
supporting information
p. 213 - 217
(2017/09/12)
-
- Cobalt-catalyzed (Z)-selective semihydrogenation of alkynes with molecular hydrogen
-
Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99 : 1 : 1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.
- Chen, Caiyou,Huang, Yi,Zhang, Zongpeng,Dong, Xiu-Qin,Zhang, Xumu
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p. 4612 - 4615
(2017/04/28)
-
- Photoinduced Nickel-Catalyzed Chemo- and Regioselective Hydroalkylation of Internal Alkynes with Ether and Amide α-Hetero C(sp3)-H Bonds
-
A direct hydroalkylation of disubstituted alkynes with unfunctionalized ethers and amides was achieved in an atom-efficient and additive-free manner through the synergistic combination of photoredox and nickel catalysis. The protocol was effective with a wide range of internal alkynes, providing products in a highly selective fashion. Notably, the observed regioselectivity is complementary to conventional radical addition processes. Mechanistic investigations suggest that the photoexcited iridium catalyst facilitated the nickel activation via single-electron transfer.
- Deng, Hong-Ping,Fan, Xuan-Zi,Chen, Zhi-Hui,Xu, Qing-Hua,Wu, Jie
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p. 13579 - 13584
(2017/10/05)
-
- Enantioselective Conjunctive Cross-Coupling of Bis(alkenyl)borates: A General Synthesis of Chiral Allylboron Reagents
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Palladium-catalyzed conjunctive cross-coupling is used for the synthesis of enantioenriched allylboron reagents. This reaction employs nonsymmetric bis(alkenyl)borates as substrates and appears to occur by a mechanism that involves selective activation of the less substituted alkene followed by migration of the more substituted alkene during the course of a Pd-induced metalate rearrangement.
- Edelstein, Emma K.,Namirembe, Sheila,Morken, James P.
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supporting information
p. 5027 - 5030
(2017/05/04)
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- Ni-Catalyzed Enantioselective Conjunctive Coupling with C(sp3) Electrophiles: A Radical-Ionic Mechanistic Dichotomy
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The catalytic enantioselective conjunctive coupling of C(sp3) electrophiles can be accomplished with Ni catalysis. The enantioselectivity of the reaction is dependent on reaction mechanism with many substrates able to engage in an asymmetric process with Pybox-Ni complexes, whereas other substrates provide racemic product mixtures. The link between substrate structure and selectivity is addressed.
- Lovinger, Gabriel J.,Morken, James P.
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supporting information
p. 17293 - 17296
(2017/12/15)
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- E-selective semi-hydrogenation of alkynes with dinuclear iridium complexes under atmospheric pressure of hydrogen
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Semi-hydrogenation of alkynes was catalyzed by halide-bridged dinuclear iridium complexes, yielding (E)-alkenes with high selectivity. Mechanistic studies conducted with monohydride dinuclear species, dihydride mononuclear species, and trihydride dinuclear species led us to propose a mechanism involving dual cycles.
- Higashida, Kosuke,Mashima, Kazushi
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supporting information
p. 866 - 868
(2016/08/13)
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- Allylic C–H Activation of Olefins by a TpMe2IrIII Compound
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The IrIIIcompound [TpMe2Ir(C6H5)2(N2)] (1) [TpMe2= hydridotris(3,5-dimethylpyrazolyl)borate] reacts with 1-hexene, propene, α-methylstyrene, and 2,3-dimethylbutadiene to yield organometallic products that derive from allylic C–H activations (complexes 3 from 1-hexene, 2 from propene, 5 from α-methylstyrene, and 7, 8, and 9 from 2,3-dimethylbutadiene), in all cases along with organic products formed in catalytic (Ir-induced) dehydrogenative coupling of benzene (the solvent of the reaction) and the corresponding olefin, with the latter also acting as the hydrogen scavenger in each case. Differently, complex 1 reacts with (E)-β-methylstyrene and cyclohexadiene to yield complex 2 and the known (η4-cyclohexadiene)IrIderivative 6, respectively. Finally, compound 1 reacts under mild conditions with cyclopentadiene and methylcyclopentadiene with the generation of phenyl derivatives 11 and 12 in which the corresponding cyclopentadienyl ligand adopts the η5coordination and forces the TpMe2ligand to coordinate in the κ2mode.
- Cristóbal, Crispín,Santos, Laura L.,Gutiérrez-González, Rubén,álvarez, Eleuterio,Paneque, Margarita,Poveda, Manuel L.
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p. 2534 - 2542
(2016/07/06)
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- E- and Z-Selective Transfer Semihydrogenation of Alkynes Catalyzed by Standard Ruthenium Olefin Metathesis Catalysts
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Selective transfer semihydrogenation of alkynes to yield alkenes was achieved with commercial first and second generation Hoveyda-Grubbs catalysts and formic acid as a hydrogen donor. This catalytic system is distinguished by its selectivity and compatibility with many functional groups (halogens, cyano, nitro, sulfide, alkenes). The metathetic activity of the ruthenium catalysts may be utilized in tandem sequences of olefin metathesis plus alkyne reduction.
- Kusy, Rafa?,Grela, Karol
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supporting information
p. 6196 - 6199
(2016/12/09)
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- Single-Electron-Transfer-Induced Coupling of Alkylzinc Reagents with Aryl Iodides
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Alkylzinc reagents prepared from an alkyllithium and zinc iodide were found to undergo coupling with aryl and alkenyl iodides in the presence of LiI in a mixed solvent consisting of THF and diglyme (1:1). Alkyllithiums, prepared by halogen–lithium exchange between an alkyl iodide and tert-butyllithium, are also converted to alkylarenes through alkylzinc reagents.
- Okura, Keisho,Shirakawa, Eiji
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supporting information
p. 3043 - 3046
(2016/07/14)
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- cis-Semihydrogenation of alkynes with amine borane complexes catalyzed by gold nanoparticles under mild conditions
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Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.
- Vasilikogiannaki, Eleni,Titilas, Ioannis,Vassilikogiannakis, Georgios,Stratakis, Manolis
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supporting information
p. 2384 - 2387
(2015/02/05)
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- MnO2/TBHP: A Versatile and User-Friendly Combination of Reagents for the Oxidation of Allylic and Benzylic Methylene Functional Groups
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In the presence of activated MnO2, tert-butyl hydroperoxide (TBHP) in CH2Cl2 is able to oxidize the allylic and benzylic methylene groups of different classes of compounds. I describe a one-pot oxidation protocol based on two sequential steps. In the first step, carried out at low temperature, MnO2 catalyses the oxidation of the methylene group. This is followed by a second step where reaction temperature is increased, allowing MnO2 both to catalyse the decomposition of unreacted TBHP and to oxidize allylic alcohols that could possibly be formed. The proposed oxidation procedure is generally applicable, although its efficiency, regioselectivity, and chemoselectivity are strongly dependent on the structure of the substrate. A simple and user-friendly synthetic procedure for the oxidation of allylic and benzylic methylene groups to the corresponding conjugated carbonyl derivatives is described. The proposed oxidation protocol is based on the combined use of MnO2 and tert-butyl hydroperoxide, and is generally applicable.
- Serra, Stefano
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supporting information
p. 6472 - 6478
(2015/10/19)
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- A transition-metal-free Heck-type reaction between alkenes and alkyl iodides enabled by light in water
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A transition-metal-free coupling protocol between various alkenes and non-activated alkyl iodides has been developed by using photoenergy in water for the first time. Under UV irradiation and basic aqueous conditions, various alkenes efficiently couple with a wide range of non-activated alkyl iodides. A tentative mechanism, which involves an atom transfer radical addition process, for the coupling is proposed.
- Liu, Wenbo,Li, Lu,Chen, Zhengwang,Li, Chao-Jun
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supporting information
p. 6170 - 6174
(2015/06/08)
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- An alkene-promoted borane-catalyzed highly stereoselective hydrogenation of alkynes to give Z- And E-alkenes
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The stereoselective hydrogenation of alkynes to alkenes is an extremely useful transformation in synthetic chemistry. Despite numerous reports for the synthesis of Zalkenes, the hydrogenation of alkynes to give E-alkenes is still not well resolved. In particular, selective preparation of both Z- and E-alkenes by the same catalytic hydrogenation system using molecular H2 has rarely been reported. In this paper, a novel strategy of using simple alkenes as promoters for the HB(C6F5)2-catalyzed metal-free hydrogenation of alkynes was adopted. Significantly, both Z - and E-alkenes can be furnished by hydrogenation with molecular H2 in high yields with excellent stereoselectivities. Further experimental and theoretical mechanistic studies suggest that interactions between H and F atoms of the alkene promoter, borane intermediate, and H2 play an essential role in promoting the hydrogenolysis reaction.
- Liu, Yongbing,Hu, Lianrui,Chen, Hui,Du, Haifeng
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supporting information
p. 3495 - 3501
(2015/03/04)
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- Improvements and Applications of the Transition Metal-Free Asymmetric Allylic Alkylation using Grignard Reagents and Magnesium Alanates
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Two new N-heterocyclic carbene (NHC) ligands have been synthesized and employed in the transition metal-free asymmetric allylic alkylation (AAA) mediated by Grignard reagents and magnesium alanates. The employment of these ligands showed high yields and improved regio- and enantioselectivity in the formation of tertiary and quaternary stereocenters. Moreover, the low catalyst loading (up to 0.3 mol%) and high scalability (up to 10 mmol) of this improved methodology provide a convenient access to biologically active compounds and synthetically valuable intermediates.
- Grassi, David,Alexakis, Alexandre
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supporting information
p. 3171 - 3186
(2015/11/03)
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- Catalytic, oxidant-free, direct olefination of alcohols using Wittig reagents
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Reported here is the catalytic, acceptorless coupling of alcohols with in situ generated, non-stabilized phosphonium ylides to form olefins as major products. The reaction uses low catalyst loadings and does not require added oxidants. Hydrogenation of the product is minimized and the reaction leads to Z (aliphatic) or E (benzylic) stereospecificity.
- Khaskin,Milstein
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supporting information
p. 9002 - 9005
(2015/05/27)
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- Direct catalytic cross-coupling of organolithium compounds
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Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern synthetic chemistry. However, the high reactivity and poor selectivity of common organolithium reagents have largely prohibited their use as a viable partner in direct catalytic cross-coupling. Here we report that in the presence of a Pd-phosphine catalyst, a wide range of alkyl-, aryl- and heteroaryl-lithium reagents undergo selective cross-coupling with aryl- and alkenyl-bromides. The process proceeds quickly under mild conditions (room temperature) and avoids the notorious lithium halogen exchange and homocoupling. The preparation of key alkyl-, aryl- and heterobiaryl intermediates reported here highlights the potential of these cross-coupling reactions for medicinal chemistry and material science.
- Giannerini, Massimo,Fananas-Mastral, Martin,Feringa, Ben L.
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p. 667 - 672
(2013/08/23)
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- Pd-catalyzed cross-coupling reactions exhibiting catalyst turnover numbers (TONs) exceeding one million
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Pd-catalyzed cross-coupling giving aryl-aryl, alkenyl-aryl, aryl-alkenyl, alkynyl-aryl, and alkynyl-alkenyl products exhibited ultra-high turnover numbers (TONs) of 0.7×107~0.69×109 by using organozincs generated in situ by treatment of the corresponding organolithiums with dry ZnBr2. Additionally, the hydrozirconation.Pd-catalyzed cross-coupling tandem processes via treatment of 1-alkynes with iBu2AlH-ZrCp2Cl2 followed by selective (≥98%) alkenyl.alkenyl coupling with either (E)- or (Z)-ethyl 3-bromoacrylate exhibited high TONs of 0.9×105~0. 81×107. Furthermore, Pd-catalyzed cross-coupling of 2-thienylzinc bromide and 1-iodo-4-nitrobenzene also showed a high TON of 0.87×105. ARKAT-USA, Inc.
- Xu, Shiqing,Truex, Nicholas L.,Mohan, Swathi,Negishi, Ei-Ichi
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p. 242 - 252
(2013/01/16)
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