- Asymmetric Hydrogenation of Aryl Perfluoroalkyl Ketones Catalyzed by Rhodium(III) Monohydride Complexes Bearing Josiphos Ligands
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The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2, Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis (up to 99 % ee) of chiral secondary alcohols with perfluoroalkyl groups. This system does not require an activating base for the hydrogenation of 2,2,2-trifluoroacetophenones. Additionally, the enantioselective C=O hydrogenations of 2-phenyl-3-(haloacetyl)-indoles, a class of privileged structures in medicinal chemistry, is reported for the first time.
- Brüning, Fabian,Nagae, Haruki,K?ch, Daniel,Mashima, Kazushi,Togni, Antonio
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supporting information
p. 10818 - 10822
(2019/07/31)
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- Unveiling the Hidden Performance of Whole Cells in the Asymmetric Bioreduction of Aryl-containing Ketones in Aqueous Deep Eutectic Solvents
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In this contribution, we report the first successful baker's yeast reduction of arylpropanones using deep eutectic solvents (DESs) as biodegradable and non-hazardous co-solvents. The nature of DES [e.g. choline chloride/glycerol (2:1)] and the percentage of water in the mixture proved to be critical for both the reversal of selectivity and to achieve high enantioselectivity on going from pure water (up to 98:2 er in favour of the S-enantiomer) to DES/aqueous mixtures (up to 98:2 er in favour of the R-enantiomer). As a result, both enantiomers of valuable chiral alcohols of pharmaceutical interest were prepared from the same biocatalyst by simply switching the solvent. The possible inhibition of some (S)-oxidoreductases making part of the genome of such a wild-type whole cell biocatalyst when DESs are used as co-solvents may pave the way for an anti-Prelog reduction. The scope and limitations of this kind of biotransformations for a range of aryl-containing ketones are also discussed. (Figure presented.).
- Vitale, Paola,Abbinante, Vincenzo Mirco,Perna, Filippo Maria,Salomone, Antonio,Cardellicchio, Cosimo,Capriati, Vito
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supporting information
p. 1049 - 1057
(2017/03/31)
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- Directed β C-H Amination of Alcohols via Radical Relay Chaperones
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A radical-mediated strategy for β C-H amination of alcohols has been developed. This approach employs a radical relay chaperone, which serves as a traceless director that facilitates selective C-H functionalization via 1,5-hydrogen atom transfer (HAT) and enables net incorporation of ammonia at the β carbon of alcohols. The chaperones presented herein enable direct access to imidate radicals, allowing their first use for H atom abstraction. A streamlined protocol enables rapid conversion of alcohols to their β-amino analogs (via in situ conversion of alcohols to imidates, directed C-H amination, and hydrolysis to NH2). Mechanistic experiments indicate HAT is rate-limiting, whereas intramolecular amination is product- and stereo-determining.
- Wappes, Ethan A.,Nakafuku, Kohki M.,Nagib, David A.
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p. 10204 - 10207
(2017/08/10)
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- Catalytic highly enantioselective transfer hydrogenation of β-trifluoromethyl nitroalkenes. An easy and general entry to optically active β-trifluoromethyl amines
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In the presence of a thiourea catalyst, β-CF3 nitroalkenes react with Hantzsch esters in a highly enantioselective fashion, giving a broad range of β-CF3 amine precursors with a tertiary stereocentre at the β-position. This reaction
- Martinelli, Emilie,Vicini, Anna Chiara,Mancinelli, Michele,Mazzanti, Andrea,Zani, Paolo,Bernardi, Luca,Fochi, Mariafrancesca
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supporting information
p. 658 - 660
(2015/01/09)
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- Screening on the use of Kluyveromyces marxianus CBS 6556 growing cells as enantioselective biocatalysts for ketone reductions
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The versatility of Kluyveromyces marxianus CBS 6556 growing cells in the enantioselective reduction of ketone functionalities to the corresponding alcohols was exploited. In particular, methyl ketones were reduced to (S)-alcohols with ees of up to 96%. Longer chain alkyl ketones afforded, under the same experimental condition, (R)-alcohols with an ee of up to 84%. Interestingly, carbon-carbon double and the triple bonds can also be reduced in the presence of Kluyveromyces marxianus CBS 6556 yeast. A cyclic ketone, such as 2-tetralone, was also quantitatively reduced to its corresponding (S)-alcohol with ee = 76%.
- Vitale, Paola,Perna, Filippo Maria,Perrone, Maria Grazia,Scilimati, Antonio
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experimental part
p. 1985 - 1993
(2012/03/22)
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- Synthesis of trifluoromethyl alcohols from tert-butoxy-β-(trifluoromethyl)styrenes and trifluoromethylbenzyl ketones under the conditions of the Leuckart-Wallach reaction
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A novel pathway towards trifluoromethylalcohols by an unexpected reaction of tert-butoxy-β-(trifluoromethyl)styrenes or corresponding trifluoromethylbenzyl ketones under the conditions of the Leuckart-Wallach reaction was elaborated.
- Muzalevskiy, Vasiliy M.,Nenajdenko, Valentine G.,Shastin, Aleksey V.,Balenkova, Elizabeth S.,Haufe, Günter
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experimental part
p. 1052 - 1055
(2009/04/04)
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- Friedel-Crafts alkylations of arenes with mono- and bis(trifluoromethyl) oxiranes in superacid medium: Facile synthesis of α-(trifluoromethyl)- and α,α-bis(trifluoromethyl)-β-arylethanols
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Triflic acid catalyzed Friedel-Crafts alkylation of aromatics with mono- and bis(trifluoromethyl)oxiranes through ring opening afforded α-(trifluoromethyl) and α,α-bis(trifluoromethyl)-β- phenylethanols in excellent yields. The regioselectivity of the oxirane ring opening and subsequent Friedel-Crafts alkylation have been found to depend on the electronic and steric effects of the substituents in the oxirane ring. DFT studies show that C2-O bond is longer than C1-O bond due to high electron-withdrawing effect of CF3 groups effecting C2-O cleavage resulting in a C2 electrophilic center promoting electrophilic substitution with the C2 center on aromatics. Georg Thieme Verlag Stuttgart.
- Prakash, G. K. Surya,Linares-Palomino, Pablo J.,Glinton, Kevin,Chacko, Sujith,Rasul, Golam,Mathew, Thomas,Olah, George A.
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p. 1158 - 1162
(2008/03/13)
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- Highly enantioselective transfer hydrogenation of fluoroalkyl ketones
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(Chemical Equation Presented) The asymmetric transfer hydrogenation of fluoroalkyl ketones mediated by [Ru(η6-arene)((S,S)-R 2NSO2DPEN)] catalysts using HCO2H-Et 3N afforded the corresponding alcohols
- Sterk, Damjan,Stephan, Michel,Mohar, Barbara
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p. 5935 - 5938
(2007/10/03)
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- Transfer hydrogenation of activated ketones using novel chiral Ru(II)-N-arenesulfonyl-1,2-diphenylethylenediamine complexes
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A series of α-keto esters and α,α,α- trifluoromethyl ketones were reduced in high yields and excellent enantioselectivities under Ru-catalysed transfer hydrogenation using novel chiral N-arenesulfonyl-1,2-diphenylethylenediamine ligands.
- ?terk, Damjan,Stephan, Massoud S.,Mohar, Barbara
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p. 535 - 537
(2007/10/03)
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- Activation of pig liver esterase in organic media with organic polymers. Application to the enantioselective acylation of racemic functionalized secondary alcohols
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Pig liver esterase (PLE) shows practically no activity in acylation of alcohols with vinylic esters in organic solvents. However, addition of methoxypoly(ethylene glycol) (MPEG), bovine serum albumin (BSA), TentaGelAmino resin (TGA), or aminomethyl polystyrene (AMPS) confers activity to PLE in acylation of alcohols with vinyl propionate in organic solvents of low water content. Polymer-activated PLE showed high enantioselectivities (E > 100) in the acylation of racemic 1-alkoxy-, 1-ethylsulfanyl-, and 1-fluoro-3-aryl-2-propanols as well as racemic 1-phenoxy-2-propanol and racemic 1-methoxy-2-phenoxy-2-propanol. The synthetic utility of polymer-activated PLE has been demonstrated by the gram-scale resolution of 1-methoxy-3-phenyl-2-propanol, 1-ethylsulfanyl-3-phenyl-2-propanol, 1-methoxy-3-p-methoxyphenyl-2-propanol, 1- fluoro-3-phenyl-2-propanol, and 1-methoxy-3-phenoxy-2-propanol. In PLE-catalyzed acylation of alcohols with vinyl propionate, acetaldehyde and propionic acids, both being detrimental to the enzyme, are formed as byproducts. In addition, the water content of the system, which is critical for the activity of pig liver esterase, is lowered because of a competing enzymatic hydrolysis of the acyl donor. The polymers TGA, BSA, and AMPS not only scavenge the aldehyde and the acid through imine formation and neutralization, respectively, but replenish at least in part also the water consumed in the competing hydrolysis of the acyl donor. A recovery of PLE together with the polymer was achieved without major loss of activity through their immobilization on a water-saturated polyaramide membrane, which occurs spontaneously in organic solvents.
- Gais,Jungen,Jadhav
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p. 3384 - 3396
(2007/10/03)
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- Enantioselective Rhodium(I)-Catalyzed Hydrogenation of Trifluoromethyl Ketones
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(Matrix Presented) The asymmetric hydrogenation of trifluoromethyl ketones to yield chiral α-trifluoromethyl alcohols with enantiomeric excesses up to 98% was achieved in the presence of chiral rhodium-(amidephosphine-phosphinite) complexes.
- Kuroki, Yoshichika,Sakamaki, Yuko,Iseki, Katsuhiko
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p. 457 - 459
(2007/10/03)
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- Two Classes of Enzymes of Opposite Stereochemistry in an Organism: One for Fluorinated and Another for Nonfluorinated Substrates
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Reduction of methyl ketones by dried cells of Geotrichum candidum (APG4) afforded (S)-alcohols in excellent enantiomeric excess (ee), whereas the reduction of trifluoromethyl ketones gave the corresponding alcohols of the opposite configuration also in excellent ee. The replacement of the methyl moiety with a trifluoromethyl group alters both the bulkiness and the electronic properties, the effect of which on the stereoselectivity was examined. No inversion in stereochemistry was observed in the reduction of hindered ketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another with the opposite stereoselectivity catalyzed the reduction of trifluoromethyl ketones. Furthermore, both APG4 and the isolated enzyme were applied to the reduction of fluorinated ketones on a preparative scale, which resulted in the synthesis of chiral fluorinated alcohols with excellent ee.
- Matsuda, Tomoko,Harada, Tadao,Nakajima, Nobuyoshi,Itoh, Toshiyuki,Nakamura, Kaoru
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p. 157 - 163
(2007/10/03)
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- α-Trifluoromethylated acyloins induce apoptosis in human oral tumor cell lines
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Cytotoxic activity of newly synthesized trifluoromethyl ketones and related compounds was studied using two human oral tumor cell lines (HSG and HSC-2). Among them, α-trifluoromethylacyloins (1 and 2) were found to induce apoptotic cell death, as judged by the terminal deoxynucleotidyl transferase (TdT) dUTP nick end-labeling (TUNEL) method which detects DNA nick or fragments. Furthermore, the cytoplasm of 1 or 2 treated HSG cells was stained by M30 monoclonal antibody, which detects the product resulting from the cleavage of cytokeratin 18 by activated caspase.
- Kawase, Masami,Sakagami, Hiroshi,Kusama, Kaoru,Motohashi, Noboru,Saito, Setsuo
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p. 3113 - 3118
(2007/10/03)
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- Highly stereocontrolled access to 1,1,1-trifluoro-2,3-epoxypropane via lipase-mediated kinetic resolution of 1,1,1-trifluoro-3-(phenylthio)propan-2-ol and its application
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1,1,1-Trifluoro-3-(phenylthio)propan-2-ol was prepared in high enantiomeric purity by lipase-mediated kinetic resolution of the corresponding esters. The resolved alcohol was successfully converted into 1,1,1 -trifluoro-2,3-epoxypropane and/or used in the
- Shimizu, Makoto,Sugiyama, Kouki,Fujisawa, Tamotsu
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p. 2655 - 2659
(2007/10/03)
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- Chiral Synthesis via Organoboranes. 40. Selective Reductions. 55. A Simple One-Pot Synthesis of the Enantiomers of (Trifluoromethyl)oxirane. A General Synthesis in High Optical Purities of α-Trifluoromethyl Secondary Alcohols via the Ring-Cleavage Reactions of the Epoxide
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An extremely efficient one-pot asymmetric synthesis of either enantiomer of (trifluoromethyl)oxirane (3,3,3-trifluoro-1,2-epoxypropane, 4) in 64percent yield and 96percent ee has been achieved via the asymmetric reduction of the commercially available 1-bromo-3,3,3-trifluoro-2-propanone with either (+)- or (-)-B-chlorodiisopinocampheylborane (Aldrich: DIP-Chloride), followed by ring closure of the intermediate chloroborinate, IpcBCl.The ring cleavage reactions of 4 provide a general synthesis of chiral trifluoromethyl carbinols without loss of optical activity.Thus we have synthesized 1-amino-3,3,3-trifluoro-2-propanol, 1-azido-3,3,3-trifluoro-2-propanol, 1-(diethylamino)-3,3,3-trifluoro-2-propanol, 1-cyano-3,3,3-trifluoro-2-propanol, 1,1,1-trifluoro-2-propanol, 1,1,1-trifluoro-2-octanol, 1-phenyl-3,3,3-trifluoro-2-propanol, 1-ethoxy-3,3,3-trifluoro-2-propanol, and 1,2-dihydroxy-3,3,3-trifluoropropane, in 61-88percent yields and in 96percent ee by the cleavage of 4 with the appropriate nucleophile.
- Ramachandran, P. Veeraraghavan,Gong, Baoqing,Brown, Herbert C.
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- Mise en evidence d'une reactivite specifique des trifluoromethylcetones vis-a-vis du bromure d'allylmagnesium
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We wish to report on an unusual reactivity of allylmagnesium bromide.This Grignard reagent acts as a reducing agent towards trifluoromethylated ketones.A single electron transfer is suggested to explain the reductive process.By using an excess of allylmagnesium bromide, an exclusive addition reaction is obtained.The stereochemistry of both addition and reduction reactions is discussed. - Keywords: Trifluoromethyl ketones; Trifluoromethyl alcohols; Allylmagnesium bromide; Single electron transfer; Stereochemistry; NMR spectroscopy; IR spectroscopy; Mass spectrometry
- Felix, Caroline,Laurent, Andre,Mison, Pierre
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- Liquid crystal compounds
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Liquid crystal compounds represented by the formula; STR1 in which Ra means an alkyl group of 1-20 carbon atoms or an alkoxy group of 1-20 carbon atoms; Rb means an aliphatic alkyl group, a branched alkyl group or an aralkyl group respectively of 1-20 carbon atoms, an alkoxy group of 1-20 carbon atoms, or an alkanoyl methyl group having 1-20 carbon atoms in the alkyl; STR2 Z means a fluorinated alkyl or a fluorinated haloalkyl; m is an integer of from 1 to 3; n is an integer of from 0 to 2 where when n is 0, Y is a single bond; and * shows an optically active center, which have a larger spontaneous polarization, high speed of response and good orientation, and show tristable liquid crystal phase.
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- TRIFLUOROPROPENE OXIDE AS A TRIFLUOROMETHYL SOURCE. PREPARATION OF OPTICALLY ACTIVE ALCOHOLS
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Optically active 3,3,3-trifluoropropene oxide (TFPO) was converted to 1,1,1-trifluoro-2-ols via Grignard type or Friedel-Crafts type reaction.The regio-selectivity of the latter reaction was discussed through an MO calculation.
- Takahashi, Osamu,Furuhashi, Keizo,Fukumasa, Mitsuo,Hirai, Toshihiro
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p. 7031 - 7034
(2007/10/02)
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- Unusual reactivity of allylmagnesium bromide
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Reaction of allylmagnesium bromide with trifluoromethyl oximes is different than with other Grignard reagents. On the other hand, allylmagnesium bromide acted as a reducing agent towards trifluoromethyl ketones. By using an excess of this Grignard reagent, an exclusive addition reaction is obtained. A single electron reaction is suggested to explain the reductive process.
- Felix, Caroline,Laurent, Andre,Mison, Pierre
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p. 4143 - 4144
(2007/10/02)
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- Oxidation of Fluoroalkyl-Substituted Carbinols by the Dess-Martin Reagent
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The efficient oxidation of mono-, di-, tri-, and perfluoroalkyl-substituted carbinols has been accommplished by the Dess-Martin periodinane oxidant.A variety of functional groups are compatible with the oxidation procedure.Monitoring the oxidation by 19F NMR indicated that a discreet periodinane intermediate is formed during the course of the reaction.Nonnucleophilic or sterically encumbered α-thiofluoro carbinols were readily oxidized; however, a nucleophilic α-thio-substituted trifluoromethyl carbinol was not.A tert-butyl alcohol modified periodinane oxidant was ultimately employed to achieve oxidation in this example.
- Linderman, Russell J.,Graves, David M.
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p. 661 - 668
(2007/10/02)
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- Homochiral Perfluoroalkyl-Group-Substituted Secondary Alcohols Through Stereoselective Reduction of Perfluoroalkyl 1-(p-Tolylsulfinyl)alkyl Ketones
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The reduction of some enantiomerically pure perfluoroalkyl α-(p-tolylsulfinyl) ketones was performed.Alcohols containing perfluoroalkyl and p-tolylsulfinyl groups were obtained with high diastereoselection when a phenyl residue was present on the sulfinylated carbon and with lower diastereoselection in the other cases.Removal of the chiral sulfinyl group from single diastereoisomers gave secondary alcohols containing a perfluoroalkyl group in enantiomerically pure form.
- Bravo, Pierfrancesco,Frigerio, Massimo,Resnati, Giuseppe
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p. 955 - 960
(2007/10/02)
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- A Microbially Based Approach for the Preparation of Chiral Molecules Possessing the Trifluoromethyl Group
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The synthetic approach to both enantiomers and diastereomers with the trifluoromethyl group, involving the stereoselective hydrolysis of the ester group and acyclic stereoselection, is described.The absolute configuration of these trifluoromethylated mole
- Lin, Jenq Tain,Yamazaki, Takashi,Kitazume, Tomoya
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p. 3211 - 3217
(2007/10/02)
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