- Fragment ion formation in resonance enhanced multiphoton ionization (REMPI) of n-propyl phenyl ether in a supersonic jet
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Resonance enhanced multiphoton ionization (REMPI) mass spectra of different conformational isomers of n-propyl phenyl ether at 30 K give the same fragmentation patterns. Laser REMPI excitation spectra exhibit three principal conformers in a supersonic free jet expansion. The most abundant species in the jet happens also to contribute the longest wavelength 0,0 band. SCF calculations suggest that the lowest energy structure corresponds to a gauche geometry in which all the carbons except that of the methyl group are essentially coplanar with the oxygen. This is confirmed by experimental observation of a predicted blue shift for a prominent vibrational overtone when the propyl group is partially deuterated (β,β-d2 or α,α,γ,γ,γ-ds). Time-of-flight mass spectra of deuterated analogues of each oF three conformers exhibits propene expulsion to yield PhOH?+ and PhOD?+ (the principal fragment ions) in which all seven alkyl hydrogens have become randomized within the chain. REMPI of individual conformer (via intermediacy of the lowest vibrational levels of their excited singlet electronic states) therefore gives the same outcome as does field ionization or electron impact source mass spectra. The predominant decomposition mechanism of the radical cation involves an ion-neutral complex, nPrOPh?+→[iPr+ PhO?], in which the hydrogens of the iPr+ undergo rapid internal transpositions prior to the ultimate decomposition step. Ab initio computations on a model system concur with the experimental inference that this mechanism operates regardless of the conformation of the precursor neutral.
- Song, Kyuseok,Van Eijk, Alexander,Shaler, Thomas A.,Morton, Thomas Hellman
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Read Online
- Removal of Alkyl Sulfonates Using DABCO
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During the route development of a midstage clinical candidate, we were challenged with a presence of alkyl sulfonates, which were identified as potential genotoxic impurities in our active pharmaceutical ingredient (API). As a result, we initiated a development effort to identify a method to remove the alkyl sulfonates that would be amenable for scale-up. Herein, we report our effort toward the development of a general approach using DABCO (1,4-diazabicyclo[2.2.2]octane) to remove alkyl sulfonates that is both efficient and convenient from the bench to scale-up.
- Corazzata, Kaitlyn,Langston, Alexander,Lee, Elaine C.,Mo, Shunyan,Rose, Peter J.,Snodgrass, Joseph
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supporting information
(2021/11/30)
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- Photoredox catalysis on unactivated substrates with strongly reducing iridium photosensitizers
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Photoredox catalysis has emerged as a powerful strategy in synthetic organic chemistry, but substrates that are difficult to reduce either require complex reaction conditions or are not amenable at all to photoredox transformations. In this work, we show that strong bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands enable high-yielding photoredox transformations of challenging substrates with very simple reaction conditions that require only a single sacrificial reagent. Using blue or green visible-light activation we demonstrate a variety of reactions, which include hydrodehalogenation, cyclization, intramolecular radical addition, and prenylationviaradical-mediated pathways, with optimized conditions that only require the photocatalyst and a sacrificial reductant/hydrogen atom donor. Many of these reactions involve organobromide and organochloride substrates which in the past have had limited utility in photoredox catalysis. This work paves the way for the continued expansion of the substrate scope in photoredox catalysis.
- Shon, Jong-Hwa,Kim, Dooyoung,Rathnayake, Manjula D.,Sittel, Steven,Weaver, Jimmie,Teets, Thomas S.
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p. 4069 - 4078
(2021/04/06)
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- N-ARYL SULFONAMIDE DERIVATIVES AS VACCINE ADJUVANT
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Bis-aryl sulfonamide compounds and methods of using those compounds, e.g., in a method of enhancing or prolonging an immune response, are provided. For example, the compounds may be employed with a vaccine and optionally at least one other adjuvant and/or one or more TLR ligands, at least one MAP kinase inhibitor, or any combination thereof.
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Page/Page column 101-102
(2021/02/26)
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- Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
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A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
- Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
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supporting information
p. 18591 - 18598
(2021/06/28)
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- Cobalt-catalyzed alkene hydrogenation by reductive turnover
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Earth abundant metal catalysts hold advantages in cost, environmental burden and chemoselectivity over precious metal catalysts. Differences in reactivity for a given metal center result from ligand field strength, which can promote reaction through either open- or closed-shell carbon intermediates. Herein we report a simple protocol for cobalt-catalyzed alkene reduction. Instead of using an oxidative turnover mechanism that requires stoichiometric hydride, we find a reductive turnover mechanism that requires stoichiometric proton. The reaction mechanism appears to involve coordination and hydrocobaltation of terminal alkenes.
- van der Puyl, Vincent,McCourt, Ruairi O.,Shenvi, Ryan A.
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supporting information
(2021/04/19)
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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p. 3082 - 3087
(2020/10/02)
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- Structure-Activity Relationship Studies to Identify Affinity Probes in Bis-aryl Sulfonamides That Prolong Immune Stimuli
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Agents that safely induce, enhance, or sustain multiple innate immune signaling pathways could be developed as potent vaccine adjuvants or coadjuvants. Using high-throughput screens with cell-based nuclear factor κB (NF-κB) and interferon stimulating response element (ISRE) reporter assays, we identified a bis-aryl sulfonamide bearing compound 1 that demonstrated sustained NF-κB and ISRE activation after a primary stimulus with lipopolysaccharide or interferon-α, respectively. Here, we present systematic structure-activity relationship (SAR) studies on the two phenyl rings and amide nitrogen of the sulfonamide group of compound 1 focused toward identification of affinity probes. The murine vaccination studies showed that compounds 1 and 33 when used as coadjuvants with monophosphoryl lipid A (MPLA) showed significant enhancement in antigen ovalbumin-specific immunoglobulin responses compared to MPLA alone. SAR studies pointed to the sites on the scaffold that can tolerate the introduction of aryl azide, biotin, and fluorescent rhodamine substituents to obtain several affinity and photoaffinity probes which will be utilized in concert for future target identification and mechanism of action studies.
- Chan, Michael,Lao, Fitzgerald S.,Chu, Paul J.,Shpigelman, Jonathan,Yao, Shiyin,Nan, Jason,Sato-Kaneko, Fumi,Li, Vicky,Hayashi, Tomoko,Corr, Maripat,Carson, Dennis A.,Cottam, Howard B.,Shukla, Nikunj M.
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supporting information
p. 9521 - 9540
(2019/11/11)
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- Chemoselective deoxygenation of ether-substituted alcohols and carbonyl compounds by B(C6F5)3-catalyzed reduction with (HMe2SiCH2)2
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B(C6F5)3-catalyzed deoxygenation of ether-substituted alcohols and carbonyl compounds has been developed using (HMe2SiCH2)2 as the reductant. This unique reagent shows distinct superiority over traditional one silicon-centered hydrosilanes, giving the corresponding alkanes in high yields with good tolerance of ethers, aryl halides and alkenes. The control experiments suggest that (HMe2SiCH2)2 might facilitate the approach in an intramolecular Si/O activation manner.
- Yang, Wenyu,Gao, Lu,Lu, Ji,Song, Zhenlei
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supporting information
p. 4834 - 4837
(2018/05/23)
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- The effect of an acylphosphine ligand on the rhodium-catalyzed hydrosilylation of alkenes
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We synthesized a series of acylphosphines and investigated the hydrosilylation of alkenes that were catalyzed using RhCl3/acylphosphine. The results indicated that RhCl3/(diphenylphosphino) (phenyl)methanone exhibited higher activity as well as higher levels of β–adduct selectivity.
- Li, Jiayun,Yang, Chuang,Bai, Ying,Yang, Xiaoling,Liu, Yu,Peng, Jiajian
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- Sodium borohydride-nickel chloride hexahydrate in EtOH/PEG-400 as an efficient and recyclable catalytic system for the reduction of alkenes
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An efficient, safe and one-pot convenient catalytic system has been developed for the reduction of alkenes using NaBH4-NiCl2·6H2O in EtOH/PEG-400 under mild conditions. In this catalytic system, a variety of alkenes (including trisubstituted alkene α-pinene) were well reduced and the Ni catalyst could be recycled.
- Li, Kaoxue,Liu, Chuanchao,Wang, Kang,Ren, Yang,Li, Fahui
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p. 7761 - 7764
(2018/03/01)
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- Synthesis of Bis(phosphino)silyl Pincer-Supported Iron Hydrides for the Catalytic Hydrogenation of Alkenes
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The synthesis and characterization of Fe pincer complexes supported by a bis(phosphino)silyl (PSiP) ligand are described. While four-coordinate species of the type (PSiP)FeX (X = halide) proved challenging to access, examples of five-coordinate (PSiP)Fe(II) and (PSiP)Fe(I) species were prepared and crystallographically characterized. In studying the reactivity of such (PSiP)Fe precursors, a variety of iron hydride species were observed and characterized, and interconversion among such complexes facilitated by the coordination of N2 was noted. The structures and spectroscopic features of several such diamagnetic Fe(II) hydrides were elucidated, including that of a unique and highly stable η2-(Si-H)Fe(II) dihydride complex. A surrogate for a low coordinate (PSiP)FeH species in the form of its bis(dinitrogen) adduct was found to be an effective precatalyst for the direct hydrogenation of alkenes, including various mono- and disubstituted aliphatic alkenes, as well as a trisubstituted example. Esters and ethers were found to be well-tolerated by the catalyst, and alkyne hydrogenation was also demonstrated.
- Murphy, Luke J.,Ferguson, Michael J.,McDonald, Robert,Lumsden, Michael D.,Turculet, Laura
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p. 4814 - 4826
(2018/12/11)
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- Catalytic Reduction of Alkyl and Aryl Bromides Using Propan-2-ol
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Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of aryl and alkyl halides under relatively mild conditions by using propan-2-ol and a base. Sterically hindered tertiary and neopentyl substrates are reduced efficiently, as well as more functionalized aryl and alkyl bromides. The reduction process is proposed to occur by radical abstraction/hydrodehalogenation steps at ruthenium. Our research represents a safer and more sustainable alternative to typical silane, lithium aluminium hydride, and tin-based conditions for these reductions.
- Haibach, Michael C.,Stoltz, Brian M.,Grubbs, Robert H.
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supporting information
p. 15123 - 15126
(2017/11/20)
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- Nitrogen-Doped Carbon-Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration in Allylarenes
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Olefin migration in allylarenes is typically performed with precious-metal-based homogeneous catalysts. In contrast, very limited progress has been made with the use of cheap, Earth-abundant base metals as heterogeneous catalysts for these transformations—in spite of the obvious economic and environmental advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular, for allylarenes. The catalyst material consists of nickel/cobalt alloy nanoparticles encapsulated in nitrogen-doped carbon shells. The encapsulated nanoparticles are stable in air and are easily collected by centrifugation, filtration, or magnetic separation. Furthermore, we demonstrate that the catalysts can be reused several times and provide continuously high yields of the olefin-migration product.
- Kramer, S?ren,Mielby, Jerrik,Buss, Kasper,Kasama, Takeshi,Kegn?s, S?ren
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p. 2930 - 2934
(2017/08/14)
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- Palladium Nanoparticle Loaded Bifunctional Silica Hybrid Material: Preparation and Applications as Catalyst in Hydrogenation Reactions
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Bifunctional mesoporous silica was prepared by co-condensation of tetraethyl orthosilicate (TEOS) with functionalized organosilanes containing azides or alkoxyamines. Orthogonal functional groups at the particles were selectively addressed in subsequent chemical modifications through “click”-chemistry (“click to ligand” strategy) and radical nitroxide exchange. Palladation with PdCl2 delivered Pd nanoparticle-loaded silica material bearing sulfoxides and additional aminoamides as stabilizing ligands by means of in situ reduction of the PdII-salt. These functional particles were successfully applied to the hydrogenation of alkynes and alkenes. Aldehyde hydrodeoxygenation and benzyl ether cleavage were achieved with these hybrid catalysts under mild conditions. Particles were analyzed by IR, TEM/STEM, EDX, and solid-state NMR spectroscopy.
- Surmiak, Sabrina K.,Doerenkamp, Carsten,Selter, Philipp,Peterlechner, Martin,Sch?fer, Andreas H.,Eckert, Hellmut,Studer, Armido
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p. 6019 - 6028
(2017/05/05)
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- Benzene C-H Etherification via Photocatalytic Hydrogen-Evolution Cross-Coupling Reaction
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Aryl ethers can be constructed from the direct coupling between the benzene C-H bond and the alcohol O-H bond with the evolution of hydrogen via the synergistic merger of photocatalysis and cobalt catalysis. Utilizing the dual catalyst system consisting of 3-cyano-1-methylquinolinum photocatalyst and cobaloxime, intermolecular etherification of arenes with various alcohols and intramolecular alkoxylation of 3-phenylpropanols with formation of chromanes are accomplished. These reactions proceed at remarkably mild conditions, and the sole byproduct is equivalent hydrogen gas.
- Zheng, Yi-Wen,Ye, Pan,Chen, Bin,Meng, Qing-Yuan,Feng, Ke,Wang, Wenguang,Wu, Li-Zhu,Tung, Chen-Ho
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supporting information
p. 2206 - 2209
(2017/05/12)
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- Design and Performance Validation of a Conductively Heated Sealed-Vessel Reactor for Organic Synthesis
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A newly designed robust and safe laboratory scale reactor for syntheses under sealed-vessel conditions at 250 °C maximum temperature and 20 bar maximum pressure is presented. The reactor employs conductive heating of a sealed glass vessel via a stainless steel heating jacket and implements both online temperature and pressure monitoring in addition to magnetic stirring. Reactions are performed in 10 mL borosilicate vials that are sealed with a silicone cap and Teflon septum and allow syntheses to be performed on a 2-6 mL scale. This conductively heated reactor is compared to a standard single-mode sealed-vessel microwave instrument with respect to heating and cooling performance, stirring efficiency, and temperature and pressure control. Importantly, comparison of the reaction outcome for a number of different synthetic transformations performed side by side in the new device and a standard microwave reactor suggest that results obtained using microwave conditions can be readily mimicked in the operationally much simpler and smaller conventionally heated device.
- Obermayer, David,Znidar, Desiree,Glotz, Gabriel,Stadler, Alexander,Dallinger, Doris,Oliver Kappe
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p. 11788 - 11801
(2016/12/09)
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- Novel, potent, selective and cellular active ABC type PTP1B inhibitors containing (methanesulfonyl-phenyl-amino)-acetic acid methyl ester phosphotyrosine mimetic
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Protein tyrosine phosphatase 1B (PTP1B) which plays an important role in the negative regulation of insulin and leptin pathway has emerged as a novel promising therapeutic target for the treatment of type 2 diabetes mellitus and obesity. Upon careful study, a series of novel scaffold and simple synthesis method inhibitors were discovered based on the analysis of X-ray crystal structures of PTP1B/inhibitor complexes and docking simulations. Among them, compound P7 exhibited high inhibitory activity (IC50 = 222 nM) with moderate selectivity (8-fold) over T-cell PTPase (TCPTP) through interacting with the A, B and C binding sites of PTP1B enzyme. Further studies on cellular activities revealed that compound P7 could enhance insulin-mediated IRβ phosphorylation and insulin-stimulated glucose uptake.
- Liu, Peihong,Du, Yongli,Song, Lianhua,Shen, Jingkang,Li, Qunyi
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p. 7079 - 7088
(2015/11/11)
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- Catalyst-free hydrogenation of alkenes and alkynes with hydrazine in the presence of oxygen
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A series of alkenes and alkynes was subjected to reduction with hydrazine hydrate in ethanol in the presence of oxygen. An efficient method was developed for the reduction of C-C double bonds and C-C triple bonds with diimide, generated in situ from hydrazine hydrate by oxidation with oxygen. The reduction process proceeded for 24-48? hours with high chemoselectivity and excellent yields. This reduction procedure offers synthetic advantages over metal-catalyzed hydrogenation as well as other systems. Georg Thieme Verlag Stuttgart New York.
- Menges, Nurettin,Balci, Metin
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p. 671 - 676
(2014/04/03)
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- Reduction of alkenes catalyzed by copper nanoparticles supported on diamond nanoparticles
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Copper nanoparticles (Cu NPs) supported on diamond nanoparticles (D NPs) previously purified by Fenton treatment (Cu/D) followed by annealing with hydrogen (Cu/DH) are highly efficient and reusable heterogeneous catalysts for hydrogenation of styrene to ethylbenzene with the minimum productivity value of 30617 cycles. The Royal Society of Chemistry.
- Dhakshinamoorthy, Amarajothi,Navalon, Sergio,Sempere, David,Alvaro, Mercedes,Garcia, Hermenegildo
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supporting information
p. 2359 - 2361
(2013/07/05)
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- Copper-promoted trifluoromethylation of primary and secondary alkylboronic acids
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New couple: The Cu-promoted trifluoromethylation of primary and secondary alkylboronic acids with TMSCF3 extends the scope of transition-metal-catalyzed trifluoromethylation reactions to sp 3-hybridized carbon centers. It also repres
- Xu, Jun,Xiao, Bin,Xie, Chuan-Qi,Luo, Dong-Fen,Liu, Lei,Fu, Yao
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p. 12551 - 12554
(2013/02/22)
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- Continuous flow hydrogenation using an on-demand gas delivery reactor
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A continuous-flow approach to the hydrogenation of alkenes utilizing Wilkinson's catalyst is reported. The approach relies on a newly developed coil design in which it is possible to load gas and heat the reaction mixture simultaneously. The hydrogenation of various substrates has been performed successfully on small scale and can be scaled up substantially.
- Mercadante, Michael A.,Kelly, Christopher B.,Lee, Christopher,Leadbeater, Nicholas E.
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supporting information; experimental part
p. 1064 - 1068
(2012/08/27)
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- Palladium on carbon-catalyzed solvent-free and solid-phase hydrogenation and Suzuki-Miyaura reaction
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The solvent-free and solid-phase hydrogenation of various reducible functionalities was efficiently catalyzed by heterogeneous palladium on carbon (Pd/C) under ambient hydrogen pressure and temperature. The Pd/C-catalyzed Suzuki-Miyaura coupling reaction between solid aryl bromides and solid arylboronic acids to generate the corresponding solid biaryls was also achieved under the totally solid-phase conditions.
- Monguchi, Yasunari,Fujita, Yuki,Hashimoto, Shota,Ina, Mariko,Takahashi, Tohru,Ito, Ryo,Nozaki, Kei,Maegawa, Tomohiro,Sajiki, Hironao
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experimental part
p. 8628 - 8634
(2011/11/30)
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- A novel method for the reduction of alkenes using the system silane/oxo-rhenium complexes
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In this work, we report the first practical application of high-valent oxo-complexes for the reduction of alkenes to the corresponding alkanes. The catalytic system Ph(Me)2SiH/ReIO2(PPh3)2 (5 mol %) proved to be very efficient for the reduction of mono- and disubstituted alkenes under solvent-free conditions.
- de Noronha, Rita G.,Rom?o, Carlos C.,Fernandes, Ana C.
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experimental part
p. 1048 - 1051
(2010/04/05)
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- Hydrogenation of olefins using Hantzsch ester catalyzed by palladium on carbon
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Hantzsch 1,4-dihydropyridine (HEH), a well-known model compound of coenzyme NAD(P)H was found as an efficient reducing agent in hydrogenation of unactivated olefins catalyzed by Pd/C. α,β-Unsaturated ketones also underwent hydrogenation, affording the corresponding saturated ketones selectively.
- Liu, Qiang,Li, Jing,Shen, Xiao-Xia,Xing, Rui-Guang,Yang, Jie,Liu, Zhengang,Zhou, Bo
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scheme or table
p. 1026 - 1028
(2009/05/11)
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- Air-initiated hydrosilylation of unactivated alkynes and alkenes and dehalogenation of halohydrocarbons by tris(trimethylsilyl)silane under solvent-free conditions
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A highly efficient air-initiated hydrosilylation of unactivated alkynes and alkenes and dehalogenation of halohydrocarbons with tris(trimethylsilyl)silane ((TMS)3SiH) as a reducing agent has been established under solvent-free conditions. These observations demonstrate that the potential and versatility of air to function as a competent initiator for Si-H bond activations. It can rival organic initiators and metal catalysts in its efficiency and is a superior initiating system from economic, environmentally sound and practical perspectives.
- Wang, Jialiang,Zhu, Zhenyu,Huang, Wen,Deng, Mingli,Zhou, Xigeng
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p. 2188 - 2192
(2008/09/21)
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- Selective reduction of mono- and disubstituted olefins by NaBH4 and catalytic RuCl3
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Direct use of the relatively inexpensive reagent, RuCl3 × H2O, as a catalyst for the reductions of olefins in the presence of water is reported. The combination of cheap and readily available sodium borohydride and a catalytic amount of RuCl3 × H2O selectively reduces mono- and disubstituted olefins, whereas trisubstituted olefins, unless activated, and benzyl ethers remain inert.
- Sharma, Pawan K.,Kumar, Surender,Kumar, Pawan,Nielsen, Poul
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p. 8704 - 8708
(2008/03/14)
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- Organosoluble copper clusters as precatalysts for carbon - Heteroelement bond-forming reactions: Microwave and conventional heating
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(Chemical Equation Presented). The coupling of aryl iodides with alcohols under mild conditions has been explored using self-assembled octanuclear copper clusters as catalysts. Reactions involving tetrahydrofurfuryl alcohol were typically complete in 4-8
- Manbeck, Gerald F.,Lipman, Adam J.,Stockland Jr., Robert A.,Freidl, Adrienne L.,Hasler, Amy F.,Stone, Joshua J.,Guzei, Ilia A.
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p. 244 - 250
(2007/10/03)
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- Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents
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Alkoxy-λ6-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, ptoluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ6-sulfanenitriles showed an opposite trend to the usual SN2 character, i.e. Me (la), Pr (1b), and Bu (1d) ? i-Pr (1c). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ6-sulfanenitrile, was found to undergo an SN2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield.
- Hao, Wei,Fujii, Takayoshi,Dong, Tiaoling,Wakai, Youko,Yoshimura, Toshiaki
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p. 193 - 198
(2007/10/03)
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- PROCESS FOR MAKING ORGANIC PRODUCTS FROM NON-PRODUCT STREAMS USING A CATALYST
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A method for preparing a product from non-product streams, such as waste or byproduct liquid streams, uses a phase transfer catalyst to enhance the reaction between two or more constituents each from a separate non-product stream. Since the non-product streams have different phases, a phase transfer catalyst may be used to transfer a chemical species from the aqueous phase to the organic phase where it will react. In one embodiment, the aqueous solution is contacted with an electrophile and a phase transfer catalyst and, optionally, a pH adjusting agent in the event that the chemical species in the aqueous solution needs to be ionized. A method for continuously preparing a product involves carrying out two processes providing two non-product streams, then contacting the two non-product streams in the presence of a phase transfer catalyst, then separating the aqueous phase from the organic phase, and then dividing the organic phase into the product and the phase transfer catalyst, which is then recycled or discarded. The catalyst can also remain in the aqueous phase and be discarded from there.
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Page/Page column 15
(2008/06/13)
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- Copper(II)-catalyzed ether synthesis from aliphatic alcohols and potassium organotrifluoroborate salts
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(Matrix presented) A protocol for the copper(II)-catalyzed etherification of aliphatic alcohols under mild and essentially neutral conditions is described. Air- and moisture-stable potassium alkenyl- and aryltrifluoroborate salts undergo cross-coupling with a variety of aliphatic primary and secondary alcohols and phenols, and are tolerant of a range of functional groups. The optimized conditions utilize catalytic copper(II) acetate with 4-(dimethylamino)pyridine as ligand in the presence of 4 A molecular sieves under an atmosphere of oxygen.
- Quach, Tan D.,Batey, Robert A.
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p. 1381 - 1384
(2007/10/03)
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- Keratinocyte growth inhibitors and hydroxamic acid derivatives
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This invention relates to a keratinocyte-proliferation inhibitor comprising as active ingredient a compound having an activity of inhibiting the solubilization of heparin-binding EGF-like growth factor bound to cell membranes and a compound of the formula (I); or pharmaceutically acceptable salt thereof, wherein R1, R2, R3 are hydrogen atom or alkyl and X is substituted benzene or the like.
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- Alkyl methyl carbonates as methylating agents. The O-methylation of phenols
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The O-methylation reaction of a variety of phenols (ArOH: Ar = Ph, p- CH3C6H4, p-ClC6H4, o- and p-CH3COC6H4, and 2-naphthyl) can be conducted in a highly selective manner by using asymmetric alkyl methyl carbonates CH3 OCOOR (R = n-Pr, 3b; n-Bu, 3d; CH3O(CH2)2O(CH2)2, 3e) as alkylating agents. For example, at 150 °C, phenol can be quantitatively converted into anisole in 4.5 h, using 2-(2-methoxyethoxy)ethyl methyl carbonate 3e in the presence of K2CO3 as a catalyst. Compared to the methylation reactions using dimethyl carbonate which require sealed pressurized reaction vessels, asymmetric alkyl methyl carbonates allow much simpler and safer alkylations at ambient pressure. The selectivity towards O- methylation is scarcely affected by the temperature (in the range of 120-150 °C), while it depends on the nature and on the amount of the solvent. DMF and triglyme (triethylene glycol dimethyl ether) have proven to be the better reaction media.
- Perosa, Alvise,Selva, Maurizio,Tundo, Pietro,Zordan, Francesco
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p. 272 - 274
(2007/10/03)
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- Arene complexes of transition metals in reactions with nucleophilic reagents. XXIX. Poly[(p-cyclopentadienylmethylstyrene)rhodium]2+ as catalyst of alkoxydefluorination of fluoroarenes
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The poly[(p-cyclopentadienylmethylstyrene)rhodium]2+ produced in situ by treating the respective dichloride complex with silver triflate in the presence of primary alcohols (methanol, propanol, hexanol) was used as catalyst grafted on polymeric sublayer for alkoxydefluorination of fluoroarenes. The activity of the catalyst in alcoholysis of fluorobenzene and p-fluorotolyene is similar to that of the corresponding homogeneous catalysts. The catalyst conserves its activity for repeated application.
- Goryunov,Steingarts
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p. 246 - 251
(2007/10/03)
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- Auxiliary accelerated reactions: Towards the use of catalytic chiral auxiliaries
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In competition experiments, the acceleration of reactivity of alkenes tethered to pyridyl groups compared with the corresponding alkenes tethered to phenyl groups in the presence of transition metals was demonstrated for two reaction types: Diels-Alder cycloaddition of enoate esters and catalytic hydrogenation of allylic and homoallylic ethers. The rate accelerations observed are of crucial importance in the development of a new concept for asymmetric catalysis: chiral auxiliaries which can function in a catalytic manner.
- Westwell, Andrew D.,Williams, Jonathan M. J.
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p. 13063 - 13078
(2007/10/03)
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- Auxiliary accelerated reactions: Catalytic hydrogenation
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In competition experiments, alkenes tethered to pyridyl groups were found to undergo indium catalysed hydrogenation more quickly than alkenes tethered to phenyl groups. This is in marked contrast to the results for hydrogenation of some of the individual substrates where alkenes tethered to pyridyl groups were reduced much more slowly than their phenyl counterparts.
- Westwell, Andrew D.,Williams, Jonathan M. J.
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- Radical isomerization via intramolecular ipso substitution of aryl ethers: Aryl translocation from oxygen to carbon
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Bromopropyl aryl ethers an converted to 3-arylpropanols under standard radical generating conditions in the presence of tributylstannane and AIBN. This rearrangement involves intramolecular ipso attack of the alkyl radicals which generates spiro cyclohexadienyl radical intermediates.
- Lee, Eun,Lee, Chulbom,Tae, Jin Sung,Whang, Ho Sung,Li, Kap Sok
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p. 2343 - 2346
(2007/10/02)
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- New Oxidative Aromatization of α,β-Unsaturated Cyclohexenones with Iodine-Cerium(IV) Ammonium Nitrate in Alcohol
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The reaction of 2-cyclohexen-1-one derivatives with iodine-cerium(IV) ammonium nitrate in alcohols (methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol) under refluxing, gave the corresponding alkyl phenyl ethers in good yields.In the case of diol (ethylene glycol, 1,3-propanediol, and 1,4-butanediol), phenoxyalkanol derivatives were obtained.The present method was also applicable to oxidative rearrangement of isophorone.
- Horiuchi, C. Akira,Fukunishi, Hirotada,Kajita, Mika,Yamaguchi, Akihisa,Kiyomiya, Hiroshi,Kiji, Shinji
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p. 1921 - 1924
(2007/10/02)
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- THE HYDROGENOLYSIS OF ORGANIC HALIDES WITH ZINC DUST IN MICELLE
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A simple and useful synthetic procedure for hydrogenolysis of organic halides with zinc dust in micellar media is described.
- Jursic, Branko,Galosi, Andreja
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p. 1649 - 1654
(2007/10/02)
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- SYNTHETIC APPLICATION OF MICELLAR CATALYSIS. WILLIAMSON'S SYNTHESIS OF ETHERS
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A simple, rapid and efficient procedure for the preparation of di-alkyl, simple phenyl-alkyl and hindered phenyl-alkyl ethers has been developed.Based on the principle of micellar catalysis the method involves alkylation of the alkoxide or the phenoxide ion with an alkyl chloride at 80 deg C in the presence of cationic micelles.For the preparation of phenyl-alkyl ethers normal micelles were used, while for the di-alkyl ethers reverse micelles were more effective.By increasing the ionic strength of the solution the rate of formation of phenyl-alkyl ethers could be increased.
- Jursic, Branko
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p. 6677 - 6680
(2007/10/02)
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- PREPARATION OF ALKYL-ARYL ETHERS AND THIOETHERS
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A method, which involves no molecular rearrangement, and which is also stereospecific, for the preparation of alkyl-aryl ethers and thioethers is described.Stable alkoxyphosphonium salts, R-O-P(1+)(NMe2)3 PF6(1-), have been prepared and treated with phenols and thiophenols, under basic conditions, to yield the corresponding alkyl-aryl ethers and thioethers respectively.
- Downie, Ian M.,Heaney, Harry,Kemp, Graham
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p. 2619 - 2624
(2007/10/02)
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- Preparation of phenolic ethers
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Phenolic ethers are produced by reacting a phenol with a compound selected from an alkyl halide, an aryl halide, a dialkyl sulphate and a diaryl sulphate in the presence as catalyst of an amidine.
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- Hydroxyalkylation with α-Hydroperoxydiazenes. Alcohols from Olefins and Carbonyl Compounds from Enol Ethers
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Alkyl(1-hydroxy-1-methylethyl)diazenes 2a-f were prepared in solution by autoxidation of the corresponding hydrazones of acetone.Thermolysis of the diazenes at 50-80 deg C in alkenes leads to alcohols.For example, 2b decomposes in 1,1-diphenylethene to afford 5-hydroxy-5,5-diphenylpentanenitrile.Alkenes with abstractable allylic hydrogens gave analogous products, but in very low yield.Thermolysis of a diazene 2 in an enol ether solvent leads to an aldehyde or a ketone.Thus, 2a decomposes in 1-ethoxyethene and in 2-methoxypropene to afford, respectively, 4,4,4-trifluorobutanal and 5,5,5-trifluoro-2-pentanone.Yields lie in range from 50percent to 70percent.The thermolysis of 2 in alkenes involves radical intermediates and radical chain hydroxyalkylation of alkene double bonds.In one chain-propagating step, R*, generated from 2, adds to the alkene.The adduct radical so formed propagates by inducing decomposition of 2 by attack at hydroxyl oxygen.According to this mechanism, initial products from enol ethers are hemiacetals or hemiketals which do not survive the reaction conditions but decompose to the corresponding carbonyl compounds.Preliminary evidence for this mechanism is presented.
- Osei-Twum, Emmanuel Y.,McCallion, Doug,Nazran, Avtar S.,Panicucci, Rick,Risbood, Prabhakar A.,Warkentin, John
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p. 336 - 342
(2007/10/02)
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- Alumina-Catalyzed Reactions of Hydroxyarenes and Hydroaromatic Ketones. 9. Reaction of Phenol with 1-Propanol
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At 250-350 deg C in the presence of alumina, phenol (1) reacts with excess 1-propanol to give mainly (>90percent) C-alkylation to form mono- to penta-n-propylphenols plus some O-alkylations to form n-propyl aryl ethers. The principal component of the product mixture from 1 is 2,6-di-n-propylphenol (26-50 mol percent yield). With 4-n-propylphenol as substrate (instead of 1), tri-, tetra-, and penta-n-propylphenols are formed in 48-79percent combined yield. On the average, only 3percent of the total C3H7 groups in the product mixture are isopropyl ones. Deoxygenation is not observed. It is proposed that the principal products result from an SN2-type reaction mechanism which involves nucleophilic attack (variously by C-2, C-4, C-6, or O) of an adsorbed ambident phenoxide ion onto C-1 of an adsorbed n-propoxide group. n-Propylation at C-3 and C-5 of the phenol ring results from surface-catalyzed dienone-phenol rearrangement.Isopropylation may occur via a side reaction of SN1 type.
- Klemm, LeRoy H.,Taylor, Dennis R.
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p. 4320 - 4326
(2007/10/02)
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- HYDROALUMINATION OF ALLYL ALCOHOLS AND ETHERS BY LITHIUM ALUMINUM HYDRIDE IN THE PRESENCE OF ZIRCONIUM CATALYST
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Allyl alcohols and ethers were readily hydroaluminated by LiAlH4 in the presence of zirconium compounds to give organoaluminum compounds in which the aluminum atom is placed at the terminal position of the substrate.ZrCl4 was the most effective catalyst for hydroalumination of allyl alcohols, whilst Cp2ZrCl2 was more effective than ZrCl4 for allyl ethers.
- Sato, Fumie,Tomuro, Yasuji,Ishikawa, Hiroaki,Sato, Masao
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- LIQUID-PHASE CATALYTIC HYDROGENATION OF UNSATURATED ETHERS
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Catalytic hydrogenation of 3-phenyloxy-1-propene, 3-phenyl-3-methoxy-1-propene, and 1-phenyl-3-methoxy-1-propene were studied at normal conditions, in substance, in methanol, and in cyclohexane on platinum and palladium carrier catalyst.The hydrogenations were usually accompanied by hydrogenolysis of the ether bond.The effects of the substance structure, solvent, and catalyst type on the course of the hydrogenation and hydrogenolysis were examined.Reaction schemes were suggested, described in some cases by power 1st order kinetic equations.
- Cerveny, Libor,Sabata, Stanislav,Ruzicka, Vlastimil
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p. 3525 - 3531
(2007/10/02)
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