- A convenient synthetic approach to a novel class of aryldifluoromethyl pyrimidine derivatives containing strobilurin motif as insecticidal agents
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A series of aryldifluoromethyl pyrimidine compounds containing strobilurin were synthesized through bioelectronic isometric design with azoxystrobin as the lead compound and a convenient approach to aryldifluoromethylpyrimidine intermediates was developed, which features mild reaction conditions and simple operation. The title compounds and aryldifluoromethylpyrimidine intermediates were characterized by NMR and HRMS. Both 7c and 7l of the preliminary screening tests showed 100% inhibition against Mythimna separata at 100 mg/L. At 20 mg/L, the lethal rate of 7l against Mythimna separata can be up to 80%.
- Cai, Zengfei,Cao, Yangyang,Du, Xiaohua,Hao, Shulin,Zhang, Wenliang
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supporting information
(2021/10/07)
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- Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
- Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
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supporting information
p. 15396 - 15405
(2021/10/12)
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- Palladium-Catalyzed Decarbonylative Iodination of Aryl Carboxylic Acids Enabled by Ligand-Assisted Halide Exchange
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We report an efficient and broadly applicable palladium-catalyzed iodination of inexpensive and abundant aryl and vinyl carboxylic acids via in situ activation to the acid chloride and formation of a phosphonium salt. The use of 1-iodobutane as iodide source in combination with a base and a deoxychlorinating reagent gives access to a wide range of aryl and vinyl iodides under Pd/Xantphos catalysis, including complex drug-like scaffolds. Stoichiometric experiments and kinetic analysis suggest a unique mechanism involving C?P reductive elimination to form the Xantphos phosphonium chloride, which subsequently initiates an unusual halogen exchange by outer sphere nucleophilic substitution.
- Boehm, Philip,Cacherat, Bastien,Lee, Yong Ho,Martini, Tristano,Morandi, Bill
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supporting information
p. 17211 - 17217
(2021/07/02)
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- Generation of Organozinc Reagents from Arylsulfonium Salts Using a Nickel Catalyst and Zinc Dust
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Readily available aryldimethylsulfonium triflates react with zinc powder under nickel catalysis via the selective cleavage of the sp2-hybridized carbon-sulfur bond to produce salt-free arylzinc triflates under mild conditions. This zincation displays superb chemoselectivity and thus represents a protocol that is complementary or orthogonal to existing methods. The generated arylzinc reagents show both high reactivity and chemoselectivity in palladium-catalyzed and copper-mediated cross-coupling reactions.
- Yamada, Kodai,Yanagi, Tomoyuki,Yorimitsu, Hideki
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p. 9712 - 9718
(2021/01/09)
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- Lipshutz-type bis(amido)argentates for directed: Ortho argentation
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Bis(amido)argentate (TMP)2Ag(CN)Li2 (3, TMP-Ag-ate; TMP = 2,2,6,6-tetramethylpiperidido) was designed as a tool for chemoselective aromatic functionalization via unprecedented directed ortho argentation (DoAg). X-Ray crystallographic analysis showed that 3 takes a structure analogous to that of the corresponding Lipshutz cuprate. DoAg with this TMP-Ag-ate afforded multifunctional aromatics in high yields in processes that exhibited high chemoselectivity and compatibility with a wide range of functional groups. These included organometallics- A nd transition metal-susceptible substituents such as methyl ester, aldehyde, vinyl, iodo, (trifluoromethanesulfonyl)oxy and nitro groups. The arylargentates displayed good reactivity with various electrophiles. Chalcogen (S, Se, and Te) installation and azo coupling reactions also proceeded efficiently.
- Tezuka, Noriyuki,Hirano, Keiichi,Peel, Andrew J.,Wheatley, Andrew E. H.,Miyamoto, Kazunori,Uchiyama, Masanobu
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p. 1855 - 1861
(2020/03/03)
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- Cathodic C-H Trifluoromethylation of Arenes and Heteroarenes Enabled by an in Situ-Generated Triflyltriethylammonium Complex
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While several trifluoromethylation reactions involving the electrochemical generation of CF3 radicals via anodic oxidation have been reported, the alternative cathodic, reductive radical generation has remained elusive. Herein, the first cathodic trifluoromethylation of arenes and heteroarenes is reported. The method is based on the electrochemical reduction of an unstable triflyltriethylammonium complex generated in situ from inexpensive triflyl chloride and triethylamine, which produces CF3 radicals that are trapped by the arenes on the cathode surface.
- Cantillo, David,Jud, Wolfgang,Kappe, C. Oliver,Maljuric, Snjezana
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supporting information
(2019/10/08)
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- Direct Pd(II)-Catalyzed Site-Selective C5-Arylation of 2-Pyridone Using Aryl Iodides
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A straightforward Pd(II)-catalyzed general strategy was developed for the C5-selective arylation of the 2-pyridone core with easily available aryl iodides. The transformation was highly regioselective and accomplished with a wide scope and functional group tolerance. Silver nitrate played a crucial role in this direct site-selective arylation. The method was extended to synthesize biologically active molecules.
- Maity, Saurabh,Das, Debapratim,Sarkar, Souradip,Samanta, Rajarshi
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supporting information
p. 5167 - 5171
(2018/09/13)
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- A general electrochemical strategy for the Sandmeyer reaction
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Herein we report a general electrochemical strategy for the Sandmeyer reaction. Using electricity as the driving force, this protocol employs a simple and inexpensive halogen source, such as NBS, CBrCl3, CH2I2, CCl4, LiCl and NaBr for the halogenation of aryl diazonium salts. In addition, we found that these electrochemical reactions could be performed using anilines as the starting material in a one-pot fashion. Furthermore, the practicality of this process was demonstrated in the multigram scale synthesis of aryl halides using highly inexpensive graphite as the electrode. A series of detailed mechanism studies have been performed, including radical clock and radical scavenger study, cyclic voltammetry analysis and in situ electron paramagnetic resonance (EPR) analysis.
- Liu, Qianyi,Sun, Beiqi,Liu, Zheng,Kao, Yi,Dong, Bo-Wei,Jiang, Shang-Da,Li, Feng,Liu, Guoquan,Yang, Yang,Mo, Fanyang
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p. 8731 - 8737
(2018/12/10)
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- Visible-Light-Induced Decarboxylative Iodination of Aromatic Carboxylic Acids
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A convenient, efficient and practical visible-light-induced decarboxylative iodination of aromatic carboxylic acids has been developed, and the corresponding aryl iodides were obtained in good yields. The method shows some advantages including the use of readily available aromatic carboxylic acids as the starting materials, simple and mild conditions, high efficiency, wide substrate scope and tolerance of various functional groups.
- Jiang, Min,Yang, Haijun,Jin, Yunhe,Ou, Lunyu,Fu, Hua
-
supporting information
p. 1572 - 1577
(2018/06/26)
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- Transition-Metal-Free Decarboxylative Iodination: New Routes for Decarboxylative Oxidative Cross-Couplings
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Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxylative iodination that occurs simply from readily available benzoic acids and I2. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxylative halogenations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxylations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxylative/C-H or double decarboxylative activations that use I2 as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxylative methods and holds other advantages over existing decarboxylative oxidative couplings, as stoichiometric transition metals are avoided.
- Perry, Gregory J. P.,Quibell, Jacob M.,Panigrahi, Adyasha,Larrosa, Igor
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supporting information
p. 11527 - 11536
(2017/08/30)
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- Copper-mediated aerobic iodination and perfluoroalkylation of boronic acids with (CF3)2CFI at room temperature
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The copper-mediated aerobic reactions between the branched (CF3)2CFI and boronic acids (R-B(OH)2) are described. Different from the linear perfluoroalkyl analogs CF3(CF2)nI (n?=?2, 3, 5, 7), (CF3)2CFI reacting with R-B(OH)2at room temperature under air in the presence of catalytic Cu powder provided exclusively the corresponding iodides (R-I), while the aerobic reactions of arylboronic acids with (CF3)2CFI at room temperature in the presence of Cu(OAc)2gave the perfluoroalkylation products (R-CF(CF3)2) in acceptable to moderate yields. The iodination reaction could be further promoted by hydroquinone, the addition of which improved the oxidation ability of (CF3)2CFI and provided the ipso-iodination products in high yields. The perfluoroalkylation was facilitated by the copper carboxylates since the addition of these salts into the reaction mixtures could successfully give rise to Ar-CF(CF3)2.
- Liu, Xi-Hai,Leng, Jing,Jia, Su-Jiao,Hao, Jian-Hong,Zhang, Fanglin,Qin, Hua-Li,Zhang, Cheng-Pan
-
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- Copper-mediated trifluoromethylation of diaryliodonium salts with difluoromethyltriflate
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The reaction of diaryliodonium salts with difluoromethyltriflate in the presence of TBAT and CuTC gave the corresponding trifluoromethylated arenes in moderate yields. Compared to other difluorocarbene-derived trifluoromethylation reactions, the current one proceeded at mild reaction conditions (room temperature) within short reaction time (5 min).
- Yang, Jing-Yun,Xu, Xiu-Hua,Qing, Feng-Ling
-
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- Copper-catalysed synthesis of trifluoromethyl(hetero)arenes from di(hetero)aryl-λ3-iodanes
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An efficient synthesis of trifluoromethylated (hetero)arenes has been achieved through the regioselective copper-catalyzed trifluoromethylation of di(hetero)aryl-λ3-iodanes, employing readily available trifluoromethyltrimethylsilane. The reaction works well for both symmetrical and unsymmetrical di(hetero)aryl-λ3-iodanes with good regioselectivity and also tolerates diverse functional groups such as bromo, iodo, cyano, nitro, ester, ketone and enolizable ketone.
- Pandey, Vinay Kumar,Anbarasan, Pazhamalai
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p. 18525 - 18529
(2016/02/27)
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- Copper-catalyzed conversion of aryl and heteroaryl bromides into the corresponding iodide
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An efficient method for the synthesis of aryl and heteroaryl iodides is described in this study. The reactions of aryl and heteroaryl bromides with potassium iodide proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding iodides in satisfactory to excellent yields.
- Feng, Xiujuan,Li, Lingyu,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
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p. 129 - 132
(2016/07/06)
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- Study on the degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3)
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Degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3), which can only be generated in situ with mixing PhI(OAc)2 and TMSCF3 in the presence of CsF, was studied by ESI-MS and GC-MS combined with 19F-NMR. The important transient intermediate PhICF3+ was determined by ESI-MS, and the major volatile products containing CF3 were identified with the authentic compounds by using GC-MS, such as trifluoromethylbenzene, 2-iodobenzotrifluoride, 3-iodobenzotrifluoride, 4-iodobenzotrifluoride. Meanwhile, more evidences obtained with 19F-NMR were given for such degradation reaction. A possible rapid CF3 radical transfer reaction pathway was proposed to clarify such degradation progress based on the experimental results. Therefore, this study may be helpful in elucidating the intrinsic reactivity of PhI(OAc)(CF3) and the possible competing side reactions caused by such self-degradation pathway. Degradation of the highly reactive hypervalent trifluoromethylation iodine reagent PhI(OAc)(CF3), which can only be generated in situ with mixing PhI(OAc)2 and TMSCF3 in the presence of CsF, was studied by ESI-MS and GC-MS combined with 19F-NMR. The important transient intermediate PhICF3+ was determined by ESI-MS, and the major volatile products containing CF3 were identified with the authentic compounds by using GC-MS, such as trifluoromethylbenzene, 2-iodobenzotrifluoride, 3-iodobenzotrifluoride, 4-iodobenzotrifluoride. Meanwhile, more evidences obtained with 19F-NMR were given for such degradation reaction. A possible rapid CF3 radical transfer reaction pathway was proposed to clarify such degradation progress based on the experimental results. Therefore, this study may be helpful in elucidating the intrinsic reactivity of PhI(OAc)(CF3) and the possible competing side reactions caused by such self-degradation pathway.
- Zhu, Hui,Zhang, Shusheng,Wang, Haoyang,Xu, Bin,Guo, Yinlong
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supporting information
p. 1365 - 1370
(2016/02/18)
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- Copper-mediated trifluoromethylation of diaryliodonium salts with TMSCF3 at room temperature
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A convenient method for the preparation of trifluoromethylated arenes from the reaction of diaryliodonium salts with TMSCF3 in the presence of CuBF4·(MeCN)4 and KF at room temperature within 25 min was developed. This reaction provides a valuable complement to the previously established trifluoromethylation methods.
- Yang, Jing-Yun,Xu, Xiu-Hua,Qing, Feng-Ling
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p. 175 - 180
(2015/10/20)
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- Silver-Catalyzed C-H Trifluoromethylation of Arenes Using Trifluoroacetic Acid as the Trifluoromethylating Reagent
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Direct trifluoromethylation of arenes using TFA as the trifluoromethylating reagent was achieved with Ag as the catalyst. This reaction not only provides a new protocol for aryl C-H trifluoromethylation, but the generation of CF3· from TFA may prove useful in other contexts and could potentially be extended to other trifluoromethylation reactions. (Chemical Equation Presented).
- Shi, Guangfa,Shao, Changdong,Pan, Shulei,Yu, Jingxun,Zhang, Yanghui
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supporting information
p. 38 - 41
(2015/07/28)
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- Trifluoromethylation of arenediazonium salts with fluoroform-derived CuCF3 in aqueous media
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A new protocol has been developed for trifluoromethylation of arenediazonium salts with moisture-sensitive CuCF3 (from fluoroform) in aqueous media. The reaction is governed by a radical mechanism, tolerates a broad variety of functional groups, and is applicable to the synthesis of complex, polyfunctionalized molecules. This journal is the Partner Organisations 2014.
- Lishchynskyi, Anton,Berthon, Guillaume,Grushin, Vladimir V.
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supporting information
p. 10237 - 10240
(2014/08/18)
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- One-pot sandmeyer trifluoromethylation and trifluoromethylthiolation
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Practical one-pot procedures were developed for both Sandmeyer-type trifluoromethylations and trifluoromethylthiolations. Starting from broadly available (hetero)aromatic amines, various benzotrifluorides were synthesized in high yields via in situ diazotization and copper-mediated trifluoromethylation using the inexpensive Ruppert-Prakash trifluoromethylating reagent. In the presence of sodium thiocyanate as a sulfur source, aryl trifluoromethyl thioethers are exclusively formed.
- Bayarmagnai, Bilguun,Matheis, Christian,Risto, Eugen,Goossen, Lukas J.
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supporting information
p. 2343 - 2348
(2014/07/21)
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- Donor-activated lithiation and sodiation of trifluoromethylbenzene: Structural, spectroscopic, and theoretical insights
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Aiming to shed new light on the stability and constitution of the organometallic intermediates involved in direct ortho-metalation processes, using trifluoromethylbenzene (1) as a case study, this paper investigates the deprotonation of 1 using group 1 alkyl bases tBuLi and nBuNa in the presence of the Lewis donors TMEDA (N,N,N′, N′-tetramethylethylenediamine), THF, and PMDETA (N,N,N′,N″, N″-pentamethyldiethylenetriamine). A systematic and comprehensive study combining structural, spectroscopic, and theoretical studies reveals that these donors strongly influence the final outcome of the reactions, not only by activating the alkali-metal bases and facilitating deprotonation of 1 but also by tuning the regioselectivity of the reaction. Thus, while using tBuLi/TMEDA, ortho-metalation of 1 is preferred, switching to THF gives a complex mixture of products with the meta-regioisomer being the major species crystallizing from hexane solution. This donor effect is significantly reduced when nBuNa is employed, as ortho-regioselectivity is observed almost exclusively using THF, TMEDA, or PMDETA. DFT calculations computing the relative energies of the ortho-, meta-, and para-regioisomers obtained from these metalating systems have also been carried out. Reinforcing the experimental findings, these theoretical studies show that although in all cases the product of ortho-metalation is the most thermodynamically preferred, the energy difference between the three possible modeled regioisomers is much larger for the Na systems than for the Li ones. The structures of key reaction intermediates [(TMEDA)·Li(C6H4-CF 3)]2 (2), [(TMEDA)·Na(C6H 4-CF3)]2 (3), and [(PMDETA)·Na(C 6H4-CF3)]2 (4) have been elucidated by X-ray crystallographic studies. All compounds exhibit a similar dimeric arrangement with a four-atom core constituting a {MCMC} ring. Interestingly for Na derivatives 3 and 4 unusual Na···F dative interactions are found, which appear to contribute to the overall stability of these compounds, therefore favoring ortho-metalation of 1, as the meta or para structures do not contain these additional interactions.
- Garden, Jennifer A.,Armstrong, David R.,Clegg, William,Garcia-Alvarez, Joaquin,Hevia, Eva,Kennedy, Alan R.,Mulvey, Robert E.,Robertson, Stuart D.,Russo, Luca
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p. 5481 - 5490
(2013/11/06)
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- Aryl radical formation by copper(I) photocatalyzed reduction of diaryliodonium salts: NMR Evidence for a CuII/CuI mechanism
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Photocatalyzed reduction of diaryliodonium salts was achieved by using [Cu(dpp)2][PF6] as a photoactive complex and DIPEA as a reductive quench. The application of a copper catalyst allows the generation of aryl radicals under mild conditions and maintains their reactivity for C-C bond formation processes.
- Baralle, Alexandre,Fensterbank, Louis,Goddard, Jean-Philippe,Ollivier, Cyril
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supporting information
p. 10809 - 10813
(2013/09/02)
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- Sandmeyer trifluoromethylation of arenediazonium tetrafluoroborates
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Copper capabilities: Diazonium salts are converted into the corresponding trifluoromethyl derivatives in the presence of a trifluoromethyl-copper complex generated in situ from CuSCN and the inexpensive, easy-to-use trifluoromethylating reagent Me3Si-CF3 (see scheme). This Sandmeyer-type reaction allows the straightforward synthesis of trifluoromethylated arenes and heteroarenes from the corresponding amines. Copyright
- Danoun, Grégory,Bayarmagnai, Bilguun,Grünberg, Matthias F.,Goo?en, Lukas J.
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p. 7972 - 7975
(2013/08/23)
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- Practical method for the Cu-mediated trifluoromethylation of arylboronic acids with CF3 radicals derived from NaSO2CF3 and tert-butyl hydroperoxide (TBHP)
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A mild and practical protocol for the copper-mediated trifluoromethylation of aryl and heteroaryl boronic acids using NaSO2CF3 (Langlois' reagent) and TBHP is described. The reaction proceeds at room temperature under ambient conditions, and the products can be readily purified by extraction or column chromatography.
- Ye, Yingda,Kuenzi, Stefan A.,Sanford, Melanie S.
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supporting information
p. 4979 - 4981,3
(2012/12/12)
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- Practical method for the Cu-mediated trifluoromethylation of arylboronic acids with CF3 radicals derived from NaSO2CF3 and tert-butyl hydroperoxide (TBHP)
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A mild and practical protocol for the copper-mediated trifluoromethylation of aryl and heteroaryl boronic acids using NaSO2CF3 (Langlois' reagent) and TBHP is described. The reaction proceeds at room temperature under ambient conditions, and the products can be readily purified by extraction or column chromatography.
- Ye, Yingda,Künzi, Stefan A.,Sanford, Melanie S.
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supporting information
p. 4979 - 4981
(2013/01/15)
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- Merging visible-light photocatalysis and transition-metal catalysis in the copper-catalyzed trifluoromethylation of boronic acids with CF3I
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This communication describes the development of a mild method for the cross-coupling of arylboronic acids with CF3I via the merger of photoredox and Cu catalysis. This method has been applied to the trifluoromethylation of electronically diverse aromatic and heteroaromatic substrates and tolerates many common functional groups.
- Ye, Yingda,Sanford, Melanie S.
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supporting information; experimental part
p. 9034 - 9037
(2012/07/13)
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- Silver-mediated trifluoromethylation of arenes using TMSCF3
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The silver-mediated C-H trifluoromethylation of aromatic substrates using TMSCF3 is described. The development, optimization, and scope of these transformations are reported. AgCF3 intermediates are proposed.
- Ye, Yingda,Lee, Shin Hee,Sanford, Melanie S.
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supporting information; experimental part
p. 5464 - 5467
(2011/12/05)
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- Hydrodehalogenation of aryl chlorides and aryl bromides using a microwave-assisted, copper-catalyzed concurrent tandem catalysis methodology
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A concurrent tandem catalytic methodology has been developed for the hydrodehalogenation of aryl bromides and aryl chlorides. The first step of the tandem catalytic cycle, halogen exchange, produced yields of 84-97% from aryl bromides using 5 mol % CuI catalyst, 10 mol % N,N′-dimethylcyclohexane-1, 2-diamine (1), and 2 equiv of NaI in acetonitrile under microwave radiation at 100 C in 0.5-1.5 h. The same reaction for aryl chlorides appeared to be equilibrium-limited after 1 hour at 200 C (yields of 5-44%). Both aryl bromides and aryl chlorides were hydrodehalogenated in 12-87% yield using 20 mol % CuI, 1.5 equiv of diamine 1, and 2 equiv of NaI in acetonitrile at 200 C after 1-2 h. Substrates with oxygen- or nitrogen-containing functional groups had substantially lower yields than hydrocarbon substrates. Deuterium labeling studies suggest that diamine 1 supplies the majority of the hydrogen for the hydrodehalogenation reaction, but solvent can also serve as a source. This article not subject to U.S. Copyright. Published 2011 by the American Chemical Society.
- Cannon, Kathleen A.,Geuther, Meagan E.,Kelly, Colin K.,Lin, Shirley,MacArthur, Amy H. Roy
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experimental part
p. 4067 - 4073
(2011/10/03)
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- Cobalt-catalyzed preparation of arylindium reagents from aryl and heteroaryl bromides
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A cobalt-bathophenanthroline catalyst has been developed for the direct preparation of a variety of arylindium reagents from the corresponding aryl and heteroaryl bromides in the presence of indium metal and lithium chloride. The thus-formed arylindium reagents undergo efficient palladium-catalyzed cross-coupling reactions with aryl iodides, tolerating various functional groups including hydroxy and free amino groups.
- Adak, Laksmikanta,Yoshikai, Naohiko
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experimental part
p. 7563 - 7568
(2011/11/12)
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- An aluminum ate base: Its design, structure, function, and reaction mechanism
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An aluminum ate base, i-Bu3Al(TMP)Li, has been designed and developed for regio- and chemoselective direct generation of functionalized aromatic aluminum compounds. Direct alumination followed by electrophilic trapping with I2, Cu/Pd-catalyzed C-C bond formation, or direct oxidation with molecular O2 proved to be a powerful tool for the preparation of 1,2- or 1,2,3-multisubstituted aromatic compounds. This deprotonative alumination using i-Bu3Al(TMP)Li was found to be effective in aliphatic chemistry as well, enabling regio- and chemoselective addition of functionalized allylic ethers and carbamates to aliphatic and aromatic aldehydes. A combined multinuclear NMR spectroscopy, X-ray crystallography, and theoretical study showed that the aluminum ate base is a Li/Al bimetallic complex bridged by the nitrogen atom of TMP and the α-carbon of an i-Bu ligand and that the Li exclusively serves as a recognition point for electronegative functional groups or coordinative solvents. The mechanism of directed ortho alumination reaction of functionalized aromatic compounds has been studied by NMR and in situ FT-IR spectroscopy, X-ray analysis, and DFT calculation. It has been found that the reaction proceeds with facile formation of an initial adduct of the base and aromatic, followed by deprotonative formation of the functionalized aromatic aluminum compound. Deprotonation by the TMP ligand rather than the isobutyl ligand was suggested and reasoned by means of spectroscopic and theoretical study. The remarkable regioselectivity of the ortho alumination reaction was explained by a coordinative approximation effect between the functional groups and the counter Li+ ion, enabling stable initial complex formation and creation of a less strained transition state structure.
- Naka, Hiroshi,Uchiyama, Masanobu,Matsumoto, Yotaro,Wheatley, Andrew E. H.,McPartlin, Mary,Morey, James V.,Kondo, Yoshinori
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p. 1921 - 1930
(2007/10/03)
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- 2,2′-bipyridine: An efficient ligand in the cobalt-catalyzed synthesis of organozinc reagents from aryl chlorides and sulfonates
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The synthesis of functionalized arylzinc reagents from aromatic chlorides, triflates, or mesylates, via cobalt catalysis, is reported using 2,2′-bipyridine as a ligand in a mixture of acetonitrile and pyridine. This procedure allows the synthesis of a variety of functionalized arylzinc species in good to excellent yields. Some of these arylzinc compounds have been coupled with aromatic bromides under palladium catalysis. Georg Thieme Verlag Stuttgart.
- Kazmierski, Igor,Gosmini, Corinne,Paris, Jean-Marc,Périchon, Jacques
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p. 881 - 884
(2007/10/03)
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- Regio- and chemoselective direct generation of functionalized aromatic aluminum compounds using aluminum ate base
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A regio- and chemoselective direct method for generation of functionalized aromatic aluminum compounds through deprotonative directed ortho-alumination using triisobutyl(tetramethylpiperidino)aluminate (iBu3Al(TMP)Li), prepared by mixing of triisobutylaluminum (iBu3Al) and lithium tetramethylpiperidide (LTMP) in THF, has been developed. Deprotonative alumination of various functionalized benzenes with the use of iBu3Al(TMP)Li proved effective for the direct generation of various ortho-functionalized aluminum aromatic and heteroaromatic derivatives, particularly those with electrophilic functional groups such as cyano, amide, and halogen. Direct alumination, followed by electrophilic trapping (with I2), provided a convenient preparative method for 1,2- or 1,2,3-multisubstituted aromatic compounds. The functionalized aromatic aluminate intermediate also was found to undergo copper- and palladium-catalyzed C-C bond-forming reactions very efficiently and highly regio- and chemoselectively. Copyright
- Uchiyama, Masanobu,Naka, Hiroshi,Matsumoto, Yotaro,Ohwada, Tomohiko
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p. 10526 - 10527
(2007/10/03)
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- The first Cu(I)-mediated nucleophilic trifluoromethylation reactions using (trifluoromethyl)trimethylsilane in ionic liquids
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The new ionic liquids (5a-8a) were used as reaction media for nucleophilic trifluoromethylation reactions of trifluoromethyl(trimethyl)silane with (1) aryl, allyl, benzyl, and alkyl halides in Cu(I)-mediated C-C bond formation reactions, and (2) carbonyl functionalities catalyzed with Ph3P or CsF. In addition, conversion of benzyl bromide as a model compound to benzyl fluoride was examined in 6a using CsF as the fluorinating reagent. The morpholiniumbased ionic liquid (6a) stood out as an efficient solvent system comparable to organic solvents and superior to the other new ionic liquids prepared in this work as well as to [bmim]+[PF6]-. Neat reactions of N-methyloxazolidine (1), Af-methylmorpholine (2), A'-methylimidazole (3) or TV-methyltriazole (4) with 2-(2-ethoxyethoxy)ethyl bromide (BrCH2CH2OCH2CH2OCH 2CH3, 9) or 2-bromoethyl methyl ether (BrCH 2CH2OCH3,10) at 75 or 105 °C gave the A'-(2-ethoxyethoxy)ethyl- or N-methoxyethyl-substituted oxazolidinium, morpholinium, imidazolium and triazolium quaternary bromides (1a-4a, 1b-4b) which were metathesized with LiN(SO2CF3)2 to form the respective roomtemperature liquid bis(trifluoromethanesulfonyl)amides 5a-8a and 5b-8b in high yields with transition or melting points 310 °C as determined by thermogravimetric analyses (TGA). Densities range between 1.29 and 1.53 g cm-3 at 25 °C.
- Kim, Jinwi,Shreeve, Jean'ne M.
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p. 2728 - 2734
(2007/10/03)
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- Syntheses and reactions of hexavalent organotellurium compounds bearing five or six tellurium-carbon bonds
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A variety of hexaorganotellurium compounds, Ar6-n(CH 3)nTe [Ar = 4-CF3C6H4, n = 0 (1a), n = 1 (3a), n = 2 (trans-4a and cis-4a), n = 3 (mer-5a), n = 4 (trans-6a); Ph, n = 0 (1b), n = 1 (3b), n = 2 (trans-4b); 4-CH3C 6H4, n = 0 (1c), n = 1 (3c), n = 2 (trans-4c), n = 4 (trans-6c); 4-BrC6H4, n = 0 (1d)] and Ar5(R)Te [Ar = 4-CF3C6H4, R = 4-CH3OC 6H4 (8); Ar = 4-CF3C6H4, R = vinyl (9), Ar = Ph, R = vinyl (10), Ar = 4-CF3C6H 4, R = PhSCH2 (11), Ar = Ph, R = PhSCH2 (12), Ar = 4-CF3C6H4, R = nBu (13)] and pentaorganotellurium halides, Ar5TeX [Ar = 4-CF3C 6H4, X = Cl (2a-Cl), X = Br (2a-Br); Ar = Ph, X = Cl (2b-Cl), X = Br (Zb-Br); Ar = 4-CH3C6H4, X = Cl (2c-Cl), X = Br (2c-Br); Ar = 4-BrC6H4, X = Br (2d-Br)] and (4-CF3C6H4)4(CH3)TeX [X = Cl (trans-7a-Cl) and X = Br (trans-7a-Br)] were synthesized by the following methods: 1) one-pot synthesis of 1a, 2) the reaction of SO 2Cl2 or Br2 with Ar5Te Li + generated from TeCl4 or TeBr4 with five equivalents of ArLi, 3) reductive cleavage of Ar6-m(CH 3)mTe (m = 0 or 2) with KC8 followed by treatment with CH3I, 4) valence expansion reaction from low-valent tellurium compounds by treatment with KC8 followed by reaction with CH3I, 5) nucleophilic substitution of Ar6-y-z(CH 3)zTeXy-z (X=Cl, Br, OTf; z = 0, 1; y= 1, 2) with organolithium reagents. The scope and limitations and some details for each method are discussed and electrophilic halogenation of the hexaorganotellurium compounds is also described.
- Miyasato, Masataka,Sagami, Takao,Minoura, Mao,Yamamoto, Yohsuke,Akiba, Kin-Ya
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p. 2590 - 2600
(2007/10/03)
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- Mechanistic study on the cross-coupling of alkynyl stannanes with aryl iodides catalyzed by η2-(dimethyl fumarate)palladium(0) complexes with iminophosphine ligands
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The reactions of [Pd(η2-dmfu)(P-N)] [dmfu = dimethyl fumarate; P-N = 2-(PPh2)C6H4-1-CH=NR, R = C6H4OMe-4 (1a), CHMe2 (2a)] and [Pd(η2-dmfu)(P-N)2] with IC6H 4CF3-4, ISnBu3 and PhC≡SnBu3 have been studied under pseudo-first-order conditions. The oxidative addition of IC6H4CF3-4 yields [PdI(C6H 4CF3-4)(P-N)] (1b or 2b). No reaction takes place with PhC≡CSnBu3 and also with ISnBu3 in the presence of an excess of PhC≡CSnBu3. In the presence of fumaronitrile (fn), 1b and 2b undergo transmetalation by PhC≡CSnBu3 followed by fast reductive elimination to yield [Pd(η2-fn)(P-N)]. The same reaction sequence occurs for the system [PdI(C6H4CF 3-4)(P-N)]/P-N (1: 1 molar ratio) to give [Pd(η2-fn) (P-N)2]. The palladium(0) complexes are active catalysts in the cross-coupling of PhC≡CSnBu3 with aryl iodides ArI (Ar = C 6H4CF3-4, Ph). The catalytic efficiency depends on the complex: [Pd(η2-dmfu)(P-N)2] > [Pd(η2-dmfu)(P-N)], and on the substituent R: C6H 4OMe-4 > CHMe2. The reactivity and spectroscopic data suggest a catalytic cycle involving initial oxidative addition of ArI to a palladium(0) species, followed by transmetalation of the product and by fast reductive elimination to regenerate the starting palladium(0) compound. For [Pd(η2-dmfu)(P-N)] as catalyst, the oxidative addition is the rate-determining step, while for [Pd(η2-dmfu)(P-N)2] the oxidative addition and the transmetalation steps occur at comparable rate. The Royal Society of Chemistry 2003.
- Crociani, Bruno,Antonaroli, Simonetta,Beghetto, Valentina,Matteoli, Ugo,Scrivanti, Alberto
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p. 2194 - 2202
(2007/10/03)
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- Vinyl carbocations: Solution studies of alkenyl(aryl)iodonium triflate fragmentations
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Generation of vinyl cations is facile by fragmentation of alkenyl(aryl)iodonium trifluoromethanesulfonates. Kinetics and electronic effects were probed by 1H NMR spectroscopy in CDCl3. Products of fragmentation include six enol triflate isomers in addition to iodoarenes. The enol triflates arise from direct reaction of a triflate anion with the starting iodonium salts as well as triflate reaction with rearranged secondary cations derived from those salts. G2 calculations of the theoretical isodesmic hydride-transfer reaction between secondary vinyl cation 7 and primary vinyl cation 6 reveal that cation 6 is 17.8 kcal/mol higher in energy. Activation parameters for fragmentation of (Z)-2-ethyl-1-hexenyl(3,5-bis-trifluoromethylphenyl)iodonium triflate, 17e, were calculated using the Arrhenius equation: Ea = 26.8 kcal/mol, ΔH? = 26.2 kcal/mol, and ΔS? = 11.9 cal/mol·K. Added triflate increases the rate of fragmentation slightly, and it is likely that for most β,β-dialkyl-substituted vinylic iodonium triflates enol triflate fragmentation products are derived from three competing mechanisms: (a) vinylic SN2 substitution; (b) ligand coupling (LC); and (c) concerted aryliodonio departure and 1,2-alkyl shift leading to secondary rather than primary vinyl cations.
- McNeil,Hinkle,Rouse,Thomas,Thomas
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p. 5556 - 5565
(2007/10/03)
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- TRIFLUORMETHYLIERUNGSREAKTIONEN VON Te(CF3)2 MIT HALOGENBENZOLEN UND METHYLBENZOLEN
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Substituent effects on yields and regioselectivity of photochemical and thermal trifluoromethylation reactions of Te(CF3)2 with halogen benzenes and methyl benzenes are investigated under comparable conditions.All reactions lead to trifluoromethylated products.The yields of the thermal are always higher than those of the corresponding photochemical reactions.The reactivity of the halobenzenes increases in the series C6H5-F a sidereaction, but H-substitution is the primary reaction pathway.During the reactions with iodobenzene tellurium containing compounds are also formed.The reactions with methyl benzenes show an increase in reactivity in the series hexamethylbenzene mesitylene toluene p-xylene.In all cases only ring substituted products are detected.Reactions with toluene and p-xylene yield tellurium containing compounds as well as addition products.The 19F-n.m.r spectra of the products are given.
- Naumann, Dieter,Kischkewitz, Jurgen
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p. 283 - 299
(2007/10/02)
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- Sodium Perfluoroalkane Carboxylates as Sources of Perfluoroalkyl Groups
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Sodium trifluoroacetate, in the presence of copper(I) iodide, is used as a source of trifluoromethyl to replace halogen by trifluoromethyl in benzenoid and heterocyclic aromatic systems, as well as in alkenyl and alkyl halogen compounds.The mechanism of this interesting copper-assisted process has been explored and an intermediate of the form - is proposed.Introduction of higher perfluoroalkyl groups from their respective sodium perfluoroalkane carboxylates has been demonstrated and the machanistic features are compared with those of the trifluoromethylation process.
- Carr, Gillian E.,Chambers, Richard D.,Holmes, Thomas F.,Parker, David G.
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p. 921 - 926
(2007/10/02)
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- Nucleophilic Displacement in Polyhalogenoaromatic Compounds. Part 11. Kinetics of Protiodeiodination of Iodoarenes in Dimethyl Sulphoxide-Methanol
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The rates of methoxide-ion induced protiodeiodination of a number of polychloroiodobenzenes and their derivatives have been measured in dimethyl sulphoxide-methanol (9:1 v/v; 323.2 K).The true reagent under these conditions appears to be the dimethyl sulphoxide anion, and the rates of reaction in some cases appear to approach that expected of a diffusion controlled process.This corresponds to a major decrease in the efficacy of further activating substituents in the aromatic system, altough deactivating groups such as p-OMe still show large effects.Chlorine promotes protiodeiodination in the order of efficiency o-Cl > m-Cl > p-Cl; the trifluoromethyl group activates displacement in the order o-CF3 > p-CF3 > m-CF3, although with much less difference between isomeric sites. o-Nitro-groups promote protiodeiodination whereas the p-nitro-group encourages methoxydeiodination.No evidence of methoxydeiodination was found in attack of the polychloroiodobenzenes, although the rates of methoxydechlorination of the corresponding polychlorobenzenes suggest that in some cases this might occur.Evidence rejecting the possible SRN1 mechanism and supporting nucleophilic attack by a carbanionic species upon iodine is presented.
- Bolton, Roger,Moore, Clive,Sandall, John P.B.
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p. 1593 - 1598
(2007/10/02)
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