- Silicone as an organosilicon reagent 2. Rhodium-catalyzed conjugate addition of the silicone reagent to α,β-unsaturated carbonyl compounds
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The reaction of poly(phenylmethylsiloxane) with α,β-unsaturated carbonyl compounds in the presence of aqueous K2CO3 and 3 mol% of [Rh(OH)(cod)]2 gives 1,4-conjugate addition product in good yields. Arylchlorosilanes also u
- Koike, Tooru,Du, Xiaoli,Mori, Atsunori,Osakada, Kohtaro
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- Rh-catalyzed 1,4-addition reactions of arylboronic acids accelerated by co-immobilized tertiary amine in silica mesopores
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Mesoporous silica-supported Rh complex catalysts were prepared by simple silane-coupling, followed by complexation, and characterized by FT-IR, SEM, Rh K-edge XAFS, and elemental analysis. Local structures of the Rh complexes in each sample were almost similar to those of a nonporous silica-supported diaminorhodium complex. Co-immobilization of a tertiary amine on the same silica surface induced slight changes to the Rh complex structure in the case of the support with smaller pores. The prepared catalysts showed high activity for the 1,4-addition reaction of phenylboronic acids. Co-immobilization of the tertiary amine increased the reaction rate by more than 7-fold, with turnover number of nearly 8500. The catalytic performance achieved with this novel system is with much higher than that reported previously with a nonporous silica-supported catalyst. The mesoporous silica-supported Rh complex-tertiary amine showed a wide substrate scope, including unsaturated ketones and nitriles. This co-immobilized tertiary amine may activate phenylboronic acid to enhance its reactivity in the transmetalation step with Rh-OH species.
- Motokura, Ken,Hashiguchi, Kohei,Maeda, Kyogo,Nambo, Masayuki,Manaka, Yuichi,Chun, Wang-Jae
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- Heterogeneous Gold Catalyst: Synthesis, Characterization, and Application in 1,4-Addition of Boronic Acids to Enones
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The new 1 wt % Au/TiO2-UVM-7 catalyst was prepared and fully characterized. This heterogeneous catalyst proved to be active, selective and recyclable for the unprecedented gold-catalyzed 1,4-addition of various functionalized arylboronic acids to 2-cyclohexen-1-one and other selected enones using toluene as a solvent. The gold-based catalyst was recycled two times and played an active role in this reaction, and the nature of the solvent determined a remarkable change in the products' selectivities.
- Moragues, Alaina,Neat?, Florentina,Pa?rvulescu, Vasile I.,Marcos, Maria Dolores,Amorós, Pedro,Michelet, Véronique
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p. 5060 - 5067
(2015/09/15)
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- 1,4-Addition of aryl boronic acids to α,β-unsaturated ketones catalyzed by a CCC-NHC pincer rhodium complex
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An air- and water-stable CCC-NHC pincer Rh complex catalyzed the 1,4-addition of aryl boronic acids to α,β-unsaturated ketones and aldehydes. This bench top method proceeds in eco-friendly solvents including methanol and water. The scope of boronic acids was expanded to include heterocyclic examples.
- Reilly, Sean W.,Box, Hannah K.,Kuchenbeiser, Glenn R.,Rubio, Ramel J.,Letko, Christopher S.,Cousineau, Kandarpa D.,Hollis, T. Keith
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supporting information
p. 6738 - 6742
(2014/12/11)
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- Efficient 1,4-addition of enones and boronic acids catalyzed by a Ni-Zn hydroxyl double salt-intercalated anionic rhodium(III) complex
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Intercalation of an in situ prepared [Rh(OH)6]3- complex into an anion exchangeable Ni-Zn layered hydroxy double salt (Rh/NiZn) was demonstrated. The resulting Rh/NiZn effectively catalyzed the 1,4-addition of diverse enones and phenylboronic acids to their corresponding β-substituted carbonyl compounds. In the case of 2-cyclohexen-1-one and phenylboronic acid, a turnover frequency (TOF) of 920 h-1 based on Rh was achieved. The [Rh(OH)6]3- complex maintained its original monomeric trivalent state within the NiZn interlayer following catalysis, attributable to a strong electrostatic interaction between the NiZn host and anionic Rh(III) complex.
- Hara, Takayoshi,Fujita, Nozomi,Ichikuni, Nobuyuki,Wilson, Karen,Lee, Adam F.,Shimazu, Shogo
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p. 4040 - 4046
(2015/02/19)
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- Palladium-catalyzed diorganozinc conjugate additions to enones: Preparative and computational studies
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The Pd-catalyzed conjugate addition of diorganozinc reagents to α,β-unsaturated carbonyl compounds has been applied to a variety of enone substrates, both cyclic and acyclic, encompassing various combinations of aryl and alkyl substitution, in combination with diorganozinc reagents incorporating alkyl (Me, linear and branched) or Ph groups. While both Pd 0 and PdII complexes have been found to be competent precatalysts, reaction yields are strongly dependent on the relative amounts of Pd to phosphane ligand. Thus, a 1:1 Pd/P ratio is well tolerated, but going to Pd/P = 1:2 leads to poor conversions and yields. A calculated Pd 0-mediated pathway involving an unusual oxidative addition step with simultaneous transmetalation, followed by reductive elimination, has been found to be compatible with the observed phosphane effect. A phosphane dependence is found in the Pd0-catalyzed diorganozinc conjugate addition to enones, which is compatible with a calculated reaction pathway proceeding through simultaneous oxidative addition/transmetalation followed by reductive elimination. Copyright
- Lorenzo, Paula,Aurrecoechea, Jose M.,De Lera, Angel R.,Alvarez, Rosana
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p. 2621 - 2626
(2013/06/04)
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- Rhodium-grafted hydrotalcite catalyst for heterogeneous 1,4-addition reaction of organoboron reagents to electron deficient olefins
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A rhodium-grafted hydrotalcite (Rh/HT) was prepared by the treatment of a Mg-Al mixed hydroxide (hydrotalcite, HT) with an aqueous RhCl 3·nH2O solution. The formation of the Rh III species on the HT surface was confirmed by X-ray absorption fine structure spectroscopy. The Rh/HT catalyst was demonstrated to effectively promote the 1,4-addition reaction of organoboron reagents to electron-deficient olefins in both organic and aqueous solvents. The strong surface basicity of HT facilitates the formation of a Rh-OH species, which possesses high nucleophilicity, leading to an efficient transmetalation with organoboron reagents. This catalyst system is also applicable in the one-pot three-component synthesis of 2-cyano-3,3-diphenyl propionate due to the bifunctionality of the Rh/HT surface.
- Motokura, Ken,Hashimoto, Norifumi,Hara, Takayoshi,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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experimental part
p. 2416 - 2422
(2011/10/13)
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- Synthesis of copper(I) complexes of N-heterocyclic carbene-phenoxyimine/ amine ligands: Structures of mononuclear copper(II), mixed-valence copper(I)/(II), and copper(II) cluster complexes
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Copper(I) bromide complexes (2a and 2b) of NHC-phenol-imine ligand precursors {3-[(1R,2R)-2-{[1-(3,5-di-tert-butyl-2-hydroxyphenyl)meth-(E)- ylidene] amino}cyclohexyl] -1-iso-propyl-4-phenyl-3H-imidazol-1-ium bromide (1a) and 3-[(1R,2R)-2-{[1-(2-hydroxyphenyl)meth-(E)-ylidene] amino}-cyclohexyl] -1-isopropyl-4-phenyl-3H-imidazol-1-ium bro-mide (1b), respectively} have been prepared. Complexes 2aand 2b exhibit copper coordination only through the carbenecarbon atom (C) and do not spontaneously eliminate HBr togive additional phenoxyimine (NO) bonds, which is attrib-uted to intramolecular hydrogen bonding. Crystallisation of2a and 2b gives 2a-and 2b-, respectively, that contain (C) copper(I) bromide and (NO)2 copper(II) coordination. Com-plex 2b-also exhibits intermolecular CuIBr interactions giv-ingaCu2Br2 bridge that links two molecules of 2b resulting in an ellipse motif. Reduction of the ligand precursor iminegroup of 1a allows synthesis of silver(I) and copper(I) NHC-phenolamine complexes 6 and 7, respectively, that also retainthe phenol hydrogen atom. Attempts to selectively prepare2a-gave a copper(II) complex 9 that exhibits an (NO)2CuIIstructure with pendant imidazolium salt groups. Reaction be-tween the silver(I) bromide derivative of 1a and CuCl2·2H2Ogives a complex derived from a Cu6(O)(OH)4Cl3 core and two(NO) and one (CNO) ligands, respectively. The use of 2a and7 as precatalysts for 1,4-conjugate addition to enones andaziridination of alkenes was studied, showing that, whilstboth catalysts are active, enantioselectivities are low, whichis attributed to the lack of Cu-(NO) coordination. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
- Simonovic, Stevan,Whitwood, Adrian C.,Clegg, William,Harrington, Ross W.,Hursthouse, Michael B.,Male, Louise,Douthwaite, Richard E.
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experimental part
p. 1786 - 1795
(2009/09/06)
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- Platinum-catalyzed 1,4-addition of arylboronic acids to β-substituted α,β-unsaturated ketones
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Platinum salts represented by K2PtCl4 were found to catalyze the 1,4-addition of arylboronic acids to β-substituted α,β-unsaturated ketones to give high yields of β-arylated ketones. The reaction is completed in 1h in the presence of 1 mol % of the catalyst in dioxane/H2O at 70 °C. Copyright
- Hayashi, Tamio,Sasaki, Keigo
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p. 842 - 843
(2008/12/22)
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- Rhodium-catalyzed aryl transfer from trisubstituted aryl methanols to α,β-unsaturated carbonyl compounds
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(Chemical Equation Presented) A process of elimination: The rhodium-catalyzed arylation of α,β-unsaturated carbonyl compounds with 9-aryl-10-benzyl-9,10-dihydroacridin-9-ols 1 as arylating reagents proceeds efficiently via β-aryl elimination of the rhodium alkoxide intermediates, to give the 1,4-addition products in high yields (see scheme; Bn = benzyl, cod = cycloocta-1,5-diene).
- Nishimura, Takahiro,Katoh, Taisuke,Hayashi, Tamio
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p. 4937 - 4939
(2008/02/08)
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- Rh-catalyzed enantioselective conjugate addition of arylboronic acids with a dynamic library of chiral tropos phosphorus ligands
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A library of 19 chiral tropos phosphorus ligands, based on a free-to-rotate (tropos) biphenol unit and a chiral P-bonded alcohol (11 phosphites, 1-P(O)2O to 11-P(O)2O) or secondary amine (8 phosphoramidites, 12-P(O)2N to 19-P(O)2N). were screened, individually and in combinations of two, in the rhodium-catalyzed asymmetric conjugate addition of arylboronic acids to enones and enoates. High enantioselectivities (up to 99% ee) and excellent yields were obtained in the addition to either cyclic or acyclic substrates. The flexible biphenolic P ligands outperformed the analogous rigid binaphtholic P ligands. Variable-temperature 31P NMR studies revealed that the biphenolic ligands are tropos even at low temperature. Only below 190 K was a coalescence observed: upon further cooling, two atropisomers were detected. The Rh homocomplexes ([Rh(La)2]+) were also studied: in general, a single doublet (P-Rh coupling) was observed in the case of the biphenolic phosphite ligands, over the temperature range 380-230 K, demonstrating their tropos nature in the rhodium complexes even at low temperatures. On the other hand, the phosphoramidites showed different behaviors depending on the structure of the ligand and on the nature of the rhodium source. The spectrum at 230 K of the mixture of [Rh(acac)(eth)2] (eth = C2H4) with phosphite 6-P(O)2O and phosphoramidite 19-P(O)2N (the most enantioselective ligand combination in the conjugate addition reaction) revealed the presence of four homocomplexes (total approximately 40%: [Rh(6-P(O)2}2], [Rh{(aR)-19-P(O)2N}2], [Rh((aS)-19-P(O)2N) 2], [Rh((aR)-19-P(O)2N}((aS)-19-P(O)2N}]) and one heterocomplex, [Rh{6-P(O)2O){(aR)-19-P(O)2NJ] (approximately 60%) In the heterocomplex, the biphenol-derived phosphite is free to rotate (tropos) while the biphenol-derived phosphoramidite shows a temperature-dependent tropos/atropos behavior (coalescence temperature = 310 K).
- Monti, Chiara,Gennari, Cesare,Piarulli, Umberto
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p. 1547 - 1558
(2008/02/03)
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- Nickel-catalyzed conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds with the aid of a catalytic amount of an alkyne
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Alkynes in combination with a catalytic amount of a nickel complex were found to catalyze the conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds, where use of an optically active alkyne induces the asymmetric addition. Copyright
- Shirakawa, Eiji,Yasuhara, Yuichi,Hayashi, Tamio
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p. 768 - 769
(2007/10/03)
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- A rhodium-grafted hydrotalcite as a highly efficient heterogeneous catalyst for 1,4-addition of organoboron reagents to α,β-unsaturated carbonyl compounds
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Treatment of a hydrotalcite with an aqueous solution of rhodium trichloride results in a Rh-grafted hydrotalcite (Rh/HT) with monomeric Rh species on the surface, which successfully promoted 1,4-addition of organoboron reagents to α,β-unsaturated carbonyl compounds. Furthermore, this catalyst was reusable and was found to be applicable to a one-pot synthesis of 3,3-diarylnitrile.
- Fujita, Noriaki,Motokura, Ken,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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p. 5083 - 5087
(2007/10/03)
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- Rhodium-catalysed 1,4-addition of diarylindium hydroxides to α,β-unsaturated carbonyl compounds
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Diarylindium(III) hydroxides react with α,β-unsaturated carbonyl compounds in the presence of a rhodium catalyst to afford the 1,4-addition products in high yield. This reaction demonstrates the utility of diarylindium(III) hydroxide as an aryl source with rhodium catalysts. The Royal Society of Chemistry 2005.
- Miura, Tomoya,Murakami, Masahiro
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p. 5676 - 5677
(2007/10/03)
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- 1,4-Addition of Arylsiloxanes to Enones Catalyzed by Dicationic Palladium(II) Complexes in Aqueous Media
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Catalytic 1,4-addition of arylsiloxanes to enones was carried out at 75°C in the presence of a dicationic palladium(II) catalyst in aqueous 1,4-dioxane. A nitrile-free complex generated in situ from Pd(dba)2 and Cu(BF4)2 in the presence of dppe or dppben was recognized to be the best catalyst to achieve high yields for the representative enones and enals.
- Nishikata, Takashi,Yamamoto, Yasunori,Miyaura, Norio
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p. 752 - 753
(2007/10/03)
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- Conjugate addition of aryl boronic acids to enones catalyzed by cationic palladium(II)-phosphane complexes
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A cationic palladium complex was found to be an efficient catalyst for the 1,4-addition of aryl boronic acids to enones at room temperature (see scheme; X= ClO4, OTf, BF4, PF6, or SbF6); Tf=trifluoromethanesulfonyl).
- Nishikata, Takashi,Yamamoto, Yasunori,Miyaura, Norio
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p. 2768 - 2770
(2007/10/03)
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- Potassium organotrifluoroborates in rhodium-catalyzed asymmetric 1,4-additions to enones
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Potassium organotrifluoroborates, highly stable organoboron derivatives, participate in asymmetric 1,4-additions to enones. This reaction, catalyzed by cationic rhodium(I) complexes chelated with binap, MeO-biphep or josiphos ligand, affords 1,4-adducts w
- Pucheault, Mathieu,Darses, Sylvain,Genet, Jean-Pierre
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p. 3552 - 3557
(2007/10/03)
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- Rhodium-catalyzed conjugate addition of aryl- and alkenyl-stannanes to α,β-unsaturated carbonyl compounds
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The addition of aryl- or alkenyl-trimethylstannanes to α,β-unsaturated carbonyl compounds in the presence of a catalytic amount of a cationic rhodium complex ([Rh(cod)(MeCN)2]BF4) and water to afford the conjugate addition products in good yields was examined. It was observed that addition of water was necessary for the reaction to proceed smoothly. The aryl- or alkenyl-rhodium complex, which is generated by the transmetalation from the organotin compound, is considered to be the active catalytic species.
- Oi, Shuichi,Moro, Mitsutoshi,Ito, Hisanori,Honma, Yoshio,Miyano, Sotaro,Inoue, Yoshio
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- Palladium(II)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Arylantimony Compounds
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Triarylstibines react with α,β-unsaturated ketones and aldehydes in acetic acid at room temperature in the presence of AgOAc and a catalytic amount of Pd(OAc)2 to afford the conjugate addition products (the formal hydroarylated compounds to an olefinic part) in good yields. In contrast, diarylantimony chlorides, arylantimony dichlorides, and diphenylantimony acetate react with the enones and enals even in the absence of AgOAc to afford the same products in higher yields compared with those from triarylstibines. These are new C-C bond-forming reactions using arylantimony(III) compounds in which the formation of a palladium enolate or a trivalent antimony enolate is proposed as an intermediate.
- Cho, Chan Sik,Motofusa, Shin-Ichi,Ohe, Kouichi,Uemura, Sakae
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p. 2341 - 2348
(2007/10/03)
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- A New Catalytic Activity of Antimony(III) Chloride in Palladium(0)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Sodium Tetraphenylborate and Arylboronic Acids
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A remarkable catalytic effect of antimony(III) chloride is disclosed in palladium(0)-catalyzed conjugate addition of aromatics to α,β-unsaturated ketones and aldehydes with sodium tetraphenylborate and arylboronic acids in acetic acid at 25 deg C.Several other metal chlorides such as AlCl3, SnCl4, AsCl3, TiCl4, FeCl3, MoCl5, and CeCl3 are also effective in some cases, but SbCl3 is the salt of choice.Two key steps are proposed for this reaction: one is the oxidative addition of a C-B bond to Pd(0) forming an arylpalladium species, and the other is the formation of an antimony enolate derived from the initial coordination of SbCl3 to the carbonyl oxygen of an organopalladium intermediate.
- Cho, Chan Sik,Motofusa, Shin-ichi,Ohe, Kouichi,Uemura, Sakae,Shim, Sang Chul
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p. 883 - 888
(2007/10/02)
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- Antimony(III) chloride as an efficient catalyst for palladium-catalyzed hydrophenylation of α,β-unsaturated ketones and aldehydes
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A remarkable catalytic effect of antimony(III) chloride was disclosed in palladium-catalyzed hydrophenylation of α,β-unsaturated ketones and aldehydes (Michael-type conjugate addition) with sodium tetraphenylborate in acetic acid at 25°C.
- Cho, Chan Sik,Motofusa, Shin-Ichi,Uemura, Sakae
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p. 1739 - 1742
(2007/10/02)
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