- Oxidative dehydrogenation of 4-arylurazoles
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4-Arylurazoles are selectively oxidized with Fe2(NO 3)3·9H2O to the corresponding Δ1-1,2,4-triazoline-3,5-diones.
- Wamhoff,Zlotskii,Saprygina
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Read Online
- Role of Heteroatoms in Diastereofacial Control in Cycloaddition to a Dissymmetric Cyclohexa-1,3-diene Moiety in a Polycyclic Framework. Remarkable Stereodirecting Influence of Distal Protective Groups
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Diels-Alder cycloaddition to several derivatives of a facially dissymmetric diene, the hexacyclo-[7.5.1.0.1,60.6,130.8,120. 10,14]pentadeca-2,4-diene-7,15-dione 4a, with a variety of dienophiles such as singlet oxygen, N-phenyltriazolinedione, dimethyl acetylenedicarboxylate, maleic anhydride, and N-methylmaleimide has been studied. The stereochemistry of the resulting adducts has been unambiguously secured by 1H and 13C NMR spectral data, chemical correlations, and X-ray crystal structure determination. While a variety of dienophiles undergo [4 + 2]-cycloadditions with 4a predominantly from the carbonyl face, protection of the carbonyl groups in 4a as simple mono- or bis-acetals 4b-e or thioacetals 9a,b leads to complete reversal in selectivity, favoring addition from the cyclobutane face, with heterodienophiles and acetylenic dienophiles. The reversal in selectivity observed in mono- and bis-acetals 4b-e has been attributed to unfavorable electrostatic interaction between the oxygen atom and the incoming dienophile. Whereas, in the case of thioacetals 9a,b, apart from unfavorable electrostatic interactions, Cieplak-type hyperconjugative interactions have to be given due consideration in order to account for the observed selectivities. Our studies highlight the role of simple protective groups (acetals in the present case) in modulating diastereoselection during [4 + 2]-cycloadditions.
- Mehta, Goverdhan,Uma
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Read Online
- METHOD FOR PRODUCING SOLID TRIAZOLINEDIONE COMPOUND, SOLID TRIAZOLINEDIONE COMPOUND, AND METHOD FOR PRODUCING TRIAZOLINEDIONE COMPOUND
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Provided are a method for separating a DAPTAD-containing triazolinedione compound in solid form from a reaction solution, a separated solid triazolinedione compound, and a novel method for producing a triazolinedione compound. A triazolinedione solution in which a DAPTAD-containing triazolinedione compound is dissolved is brought into contact with a C5-15 hydrocarbon-based poor solvent to obtain a solid triazolinedione compound. Also, a triazolinedione compound is oxidized using an oxidizing agent that does not produce acid as a byproduct to obtain a triazolinedione compound.
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Paragraph 0160-0163
(2020/12/25)
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- Diazacyclobutene derivatives and methods of synthesis thereof
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Provided is a compound having the formula: wherein: R1 is selected from the group consisting of H, aliphatic of 1 to 100 carbons and arene comprising up to 100 carbons; R2 is selected from the group consisting of H, aliphatic of 1 to 100 carbons and arene comprising up to 100 carbons; each R3 is independently selected from the group consisting of H, aliphatic of 1 to 100 carbons and arene comprising up to 100 carbons; X is selected from the group consisting of B, O, N, S, Se and P; and n is 1-4 as necessary to complete the valence of X formed by the reaction of a compound of Formula III: and a compound of Formula IV:
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Page/Page column 12
(2021/01/17)
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- 1,2-Diazacyclopentane-3,5-diyl Diradicals: Electronic Structure and Reactivity
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Localized singlet diradicals are key intermediates in bond homolysis. A thorough study of the reactive species is needed to clarify the mechanisms of the homolytic bond cleavage and formation processes. In general, the singlet diradicals are quite short-lived because of the fast radical-radical coupling reactions. The short-lived characteristic has retarded the thorough study on bond homolysis. In this study, a new series of long-lived singlet diradicals, viz., 1,2-diazacyclopentane-3,5-diyl, were identified, and their electronic structures and novel reactivities were thoroughly studied using laser-flash photolysis (LFP), product analysis, and computational studies. A direct observation of the thermal equilibration (fast process) between the singlet diradicals and the corresponding ring-closing compounds was undertaken on the submicrosecond time scale. The solvent and substituent effects on the equilibration constant and rate constants for the ring-closing reaction and ring-opening reaction clarify the novel nitrogen-atom effect on the localized singlet 1,3-diyl diradicals. Two types of alkoxy-migrated compounds, 9 and 10, were isolated with high yields as the final products. Crossover, spin-trapping, and LFP experiments for the formation of alkoxy-group migration products (i.e., 9 versus 10) revealed the unique temperature effect on the product ratio of the two types of alkoxy-migration products. The temperature-insensitive intersystem crossing process (slow process, millisecond time scale) was found to be a key step in the formation of 9, which is an entropy-controlled pathway. An intramolecular migration process was identified for the formation of 10 that was accelerated by a polar solvent in an enthalpy-controlled process. This unique heteroatom effect has opened up a new series of localized singlet diradicals that are crucial intermediates in bond homolysis.
- Yoshidomi, Shohei,Abe, Manabu
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supporting information
p. 3920 - 3933
(2019/03/07)
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- [2π + 2π]-Cycloaddition of biadamantylidene to 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione. Effects of temperature, high pressure, and solvent
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The effects of temperature, solvent nature, and high hydrostatic pressure on the rate of the reaction of biadamantylidene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione have been estimated. Significant shielding of the C=C double bond in biadamantylidene is responsible for the high entropy and volume of activation. Quantitative yield of the reaction in the temperature range 25?45°C is related to its exothermicity. The rate of the [2π + 2π]-cycloaddition unexpectedly weakly depends on the solvent polarity, which makes it radically different from the [2π + 2π]-reaction with tetracyanoethylene.
- Kiselev,Kornilov,Anikin,Sedov,Konovalov
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p. 1864 - 1869
(2018/02/06)
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- Method for preparing 3,5-dioxo-1,2,4-triazole
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The invention provides a method for preparing 3,5-dioxo-1,2,4-triazole. The method is characterized in that WO3-x nanosheets with oxygen vacancies are taken as a catalyst under the acidic condition, hydrated sodium tungstate is taken as a raw material, an appropriate quantity of additives are added to a solvent, and 3,5-dioxo-1,2,4-triazole is further directly synthesized through solvent heat or with a direct heating method; the WO3-x nanosheets with the oxygen vacancies are firstly prepared, tungsten oxide nanosheets catalyze and oxidize sulfur oxide, and 3,5-dioxo-1,2,4-triazole is prepared. According to the method, the reaction conditions are simple, the cost is low, no pollution is caused, and the method has important industrial application value and important environmental and social meaning.
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Paragraph 0046; 0047; 0048; 0049; 0050; 0051
(2016/10/27)
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- Kinetic and equilibrium parameters of [4+2] cycloaddition reaction of 2,6-dimethylnaphthalene with 4-phenyl-1,2,4-triazoline-3,5-dione
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Kinetic parameters of forward and retro Diels-Alder reactions between 2,6-dimethylnaphthalene and 4-phenyl-1,2,4-triazolinedione were determined, as well as the equilibrium parameters of the reaction in 1,2-dichloroethane.
- Kiselev,Kashaeva,Potapova,Kornilov,Konovalov
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p. 770 - 771
(2015/01/30)
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- Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione
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The Diels-Alder reaction between substituted anthracenes 1a-1j and 4-phenyl-1,2,4-triazoline-3,5 (2) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a. The structure of adduct 3a is proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ? 3a in toluene at 25°C: Keq = 2120 M-1, ΔHf≠ = 58.6 kJ/mol, ΔSf≠ = -97 J/(mol K), ΔVf≠ = -17.2 cm3/mol, ΔHb ≠ = 108.8 kJ/mol, ΔSb≠ = 7.3 J/(mol K), ΔVb≠ = -0.8 cm3/mol, ΔHr-n = -50.2 kJ/mol, ΔSr-n = -104.3 J/(mol K), ΔVr-n = -15.6 cm3/mol. It is concluded that the values of equilibrium constants of the reactions 1a-1j + 2 ? 3a-3j vary within 4 × 101-1011 M-1.
- Kiselev,Kornilov,Kashaeva,Potapova,Krivolapov,Litvinov,Konovalov
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p. 2073 - 2080
(2015/02/19)
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- Facile and stabile linkages through tyrosine: Bioconjugation strategies with the tyrosine-click reaction
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The scope, chemoselectivity, and utility of the click-like tyrosine labeling reaction with 4-phenyl-3H-1,2,4-triazoline-3,5(4H)-diones (PTADs) is reported. To study the utility and chemoselectivity of PTAD derivatives in peptide and protein chemistry, we synthesized PTAD derivatives possessing azide, alkyne, and ketone groups and studied their reactions with amino acid derivatives and peptides of increasing complexity. With proteins we studied the compatibility of the tyrosine click reaction with cysteine and lysine-targeted labeling approaches and demonstrate that chemoselective trifunctionalization of proteins is readily achieved. In particular cases, we noted that PTAD decomposition resulted in formation of a putative isocyanate byproduct that was promiscuous in labeling. This side reaction product, however, was readily scavenged by the addition of a small amount of 2-amino-2-hydroxymethyl-propane- 1,3-diol (Tris) to the reaction medium. To study the potential of the tyrosine click reaction to introduce poly(ethylene glycol) chains onto proteins (PEGylation), we demonstrate that this novel reagent provides for the selective PEGylation of chymotrypsinogen, whereas traditional succinimide-based PEGylation targeting lysine residues provided a more diverse range of PEGylated products. Finally, we applied the tyrosine click reaction to create a novel antibody-drug conjugate. For this purpose, we synthesized a PTAD derivative linked to the HIV entry inhibitor aplaviroc. Labeling of the antibody trastuzumab with this reagent provided a labeled antibody conjugate that demonstrated potent HIV-1 neutralization activity demonstrating the potential of this reaction in creating protein conjugates with small molecules. The tyrosine click linkage demonstrated stability to extremes of pH, temperature, and exposure to human blood plasma indicating that this linkage is significantly more robust than maleimide-type linkages that are commonly employed in bioconjugations. These studies support the broad utility of this reaction in the chemoselective modification of small molecules, peptides, and proteins under mild aqueous conditions over a broad pH range using a wide variety of biologically acceptable buffers such as phosphate buffered saline (PBS) and 2-amino-2-hydroxymethyl- propane-1,3-diol (Tris) buffers as well as others and mixed buffered compositions.
- Ban, Hitoshi,Nagano, Masanobu,Gavrilyuk, Julia,Hakamata, Wataru,Inokuma, Tsubasa,Barbas, Carlos F.
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p. 520 - 532
(2013/06/05)
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- N2O4 chemisorbed onto n-propylsilica kryptofix 21 and kriptofix 22 as two new functional polymers for the fast oxidation of urazoles and 1,4-dihydropyridines
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3-Chloropropylsilica was reacted with Kriptofix 21 or 22 in the presence of triethylamine to form N-propylsilica Kryptofix 21 and Kriptofix 22. Then N 2O4 was added to each of these polymers to chemisorb onto cavity of aza-crown ethers. These functionalized polymers were applied for the fast and simple oxidation of urazoles and 1,4-dihydropyridines, respectively.
- Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Ghaemi, Ezat,Madrakian, Elaheh,Niknam, Khodabakhsh,Mallakpour, Shadpour
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experimental part
p. 596 - 599
(2012/09/07)
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- Oxidative ring cleavage of 4-(4-R-phenyl)-1,2,4-triazolidine-3,5-diones: Electrochemical behavior and kinetic study
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Cyclic voltammetry results as a diagnostic technique for electrochemical oxidation of 4-(4-R-phenyl)-1,2,4-triazolidine-3,5-diones (1-5) are reported and discussed. The results indicate that the electrochemically generated 4-(4-R-phenyl)-4H-1,2,4-triazole-3,5-diones (1ox-5ox) are unstable and participate in oxidative ring cleavage. In this study, the effect of different parameters such as pH, 4-phenylurazole concentration, solvent, temperature, substitute effect and time window of chosen electrochemical method have been studied. Also, the transfer coefficient, α, exchange current density, J0, the formal potential, E0′ and diffusion coefficient, D, of 4-phenylurazole (1) have been calculated. In addition, the observed homogeneous rate constants of oxidative ring cleavage of 4-phenylurazole derivatives were estimated by comparing the experimental cyclic voltammetric responses with digital simulated results.
- Varmaghani,Nematollahi,Mallakpour
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scheme or table
p. F174-F180
(2012/07/28)
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- Oxidation of urazoles to their corresponding triazolinediones using benzyltriphenylphosphonium nitrate
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Benzyltriphenylphosphonium nitrate in the presence of AlCl3 oxidised 1,2,4-triazolidine-3,5-diones to the corresponding 4-substituted-1,2,4- triazole-3,5-diones.
- Samimi, Heshmat Allah,Parvanak, Kaveh
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experimental part
p. 272 - 274
(2011/10/07)
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- Dynamic Covalent chemistry: A facile room-temperature, reversible, diels-alder reaction between anthracene derivatives and n-phenyltriazolinedione
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A series of readily accessible, dynamic Diels-Alder reactions that are reversible at room temperature have been developed between anthracene derivatives as dienes and N-phenyl-1,2,4-triazoline-3,5-dione as the dienophile. The adducts formed undergo reversible component exchange to form dynamic libraries of equilibrating cycloadducts. Furthermore, reversible adduct formation allows temperature-dependent modulation of the fluorescent properties of anthracene components; a feature of potential interest for the design of optodynamic polymeric materials by careful selection and manipulation of these simple dienes and dienophiles. Copyright
- Roy, Nabarun,Lehn, Jean-Marie
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p. 2419 - 2425
(2012/07/03)
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- Catalytic and efficient oxidation of urazole derivatives to their corresponding triazolinediones using ammonium nitrate and metal hydrogen sulfate as catalyst
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Catalytic oxidation of a variety of urazoles to the triazolinediones via combination of NH4NO3 in the presence of a catalytic amount of aluminium hydrogen sulfate has been developed at room temperature in dichloromethane.
- Ghorbani-Choghamarani, Arash,Zeinivand, Javad,Mallakpour, Shadpour
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experimental part
p. 1189 - 1192
(2010/11/19)
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- Metal-Free oxidation of urazole and 1,4-dihydropyridine derivatives under mild and heterogeneous conditions by nitro urea, derived from urea nitrate, and silica sulfuric acid
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Mild combination of nitro urea, derived from urea nitrate, and silica sulfuric acid (SiO2OSO3H) might act as an efficient oxidizing media, which could be able to oxidize different types of heterocyclic compounds including urazoles and 1,4-dihydropyridines. The process presented here is operationally simple, environmentally benign, and reactions have been mildly carried out in dichloromethane at room temperature.
- Ghorbani-Choghamarani, Arash,Zolfigol, Mohammad A.,Hajjami, Maryam,Rastgoo, Shahrbanoo,Mallakpour, Shadpour
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experimental part
p. 249 - 254
(2011/07/30)
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- Supported nitric acid on silica gel and polyvinyl pyrrolidone (PVP) as an efficient oxidizing agent for the oxidation of urazoles and bis-urazoles
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A method for the oxidation of a good range of urazoles and bis-urazoles to the corresponding triazolinediones by supported nitric acid on silica gel (SiO2-HNO3) and/or polyvinyl pyrrolidone (PVP-HNO3) is described. Reactions have been carried out heterogeneously at room temperature in dichloromethane with good to excellent yields.
- Ghorbani-Choghamarani, Arash,Chenani, Zahra,Mallakpour, Shadpour
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experimental part
p. 4264 - 4270
(2010/01/09)
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- Catalytic oxidation of urazoles and bis-urazoles to their corresponding triazolinediones using aluminium nitrate and a catalytic amount of silica sulfuric acid
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A simple and efficient catalytic oxidation of urazoles and a bis-urazole to the corresponding triazolinediones by treatment with Al(NO3) 3.9H2O in the presence of a catalytic amount of silica sulfuric acid is described. A good range of urazole derivatives was selectively oxidized in CH2Cl2 at room temperature in good to excellent yields.
- Ghorbani-Choghamarani, Arash,Hajjami, Maryam,Goudarziafshar, Hamid,Nikoorazm, Mohsen,Mallakpour, Shadpour,Sadeghizadeh, Fatemeh,Azadi, Gouhar
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experimental part
p. 607 - 610
(2010/05/02)
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- Iodogen: A novel reagent for the oxidation of urazoles under heterogeneous conditions
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Iodogen is employed as an efficient oxidizing agent for the conversion of urazoles and bis-urazoles into the corresponding 1,2,4-triazoles in good to excellent yields under mild heterogeneous conditions at room temperature. Georg Thieme Verlag Stuttgart.
- Khoramabadi-Zad, Ahmad,Shiri, Azam,Zolfigol, Mohammad Ali,Mallakpour, Shadpour
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experimental part
p. 2729 - 2732
(2010/01/21)
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- Silica-supported ICI as a novel heterogeneous system for the rapid oxidation of urazoles to triazolinediones
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ICl-SiO2 as a new reactive system was prepared by the treatment of iodine monochloride with an activated silica gel in chloroform. ICl-SiO 2 in a heterogeneous system efficiently oxidized urazoles to the corresponding triazolinediones under mild conditions in high yields at room temperature.
- Karami, Bahador,Mallakpour, Shadpour,Farahi, Mahnaz
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p. 389 - 393
(2008/09/20)
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- N-bromo reagent mediated oxidation of urazoles to their corresponding triazolinediones under mild and heterogeneous conditions
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Various N-bromo reagents [HMTAB, DABCO-bromine, DPTBE, and TBCA] were used as effective oxidizing agents for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones under mild and heterogeneous conditions at room temperature with good to excellent yields. Also the oxidation of some new 4-phenylurazole derivatives with these reagents is discussed.
- Zolfigol, Mohammad Ali,Chehardoli, Gholamabbas,Ghaemi, Ezat,Madrakian, Elaheh,Zare, Reza,Azadbakht, Tahereh,Niknam, Khodabakhsh,Mallakpour, Shadpour
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experimental part
p. 261 - 265
(2009/05/26)
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- PEG-N2O4 system as an efficient reagent both for the rapid oxidation of urazoles and 1,4-dihydropyridines under nonaqueous conditions
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N2O4 was easily impregnated on polyethyleneglycol to give a stable reagent. Polyethyleneglycol-N2O4 (PEG-N 2O4) system was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones and also for the aromatization of 1,4-dihydropyridines into the corresponding pyridine derivatives under mild conditions at room temperature with good to excellent yields.
- Zolfigol, Mohammad Ali,Ghaemi, Ezat,Madrakian, Elaheh,Niknam, Khodabakhsh
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experimental part
p. 704 - 711
(2009/05/26)
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- Clean synthesis of azo compounds using Magtrieve in the ionic liquid [bmim][Br]
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A series of azo compounds, N-aryl-2-phenyldiazenecarboxamides, and 4-substituted-1,2,4-triazoline-3,5-diones, were synthesized using Magtrieve, a magnetically retrievable and recyclable oxidant, in the ionic liquid [bmim][Br] under neutral condition. This procedure has several advantages, such as greenness, mild reactions, simple manipulation, and reusability of reagent and solvent.
- Wan, Hui,Peng, Yanqing
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experimental part
p. 909 - 912
(2009/09/25)
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- Type 2 intramolecular N-acylazo Diels-Alder reaction: Regio- and stereoselective synthesis of bridgehead bicyclic 1,2-diazines
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(Chemical Equation Presented) The type 2 intramolecular N-acylazo Diels-Alder reaction provides a regio- and stereoselective synthesis of bicyclic 1,2-diazine systems. A new method for the generation of N-acylazo dienophiles with tetra-n-butylammonium periodate is reported. X-ray crystallographic analysis allowed the quantification of structural distortions of the nonplanar bridgehead olefin and lactam functionalities in 1,2-diazine cycloadducts 11 and 15. Caprolactams and enantholactams were formed by stereoselective bridgehead alkene reduction, a process that transfers stereochemistry from the bridgehead lactam nitrogen to the bridgehead carbon. The sequence of transformations offers a convenient route for the diastereoselective synthesis of medium-ring nitrogen heterocycles and 1,4-diamines.
- Molina, Claudia L.,Chow, Chun P.,Shea, Kenneth J.
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p. 6816 - 6823
(2008/02/10)
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- Oxidation of urazoles with 1,3-dihalo-5,5-dimethylhydantoin, both in solution and under solvent-free conditions
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1,3-dichloro-5,5-dimethylhydantoin (DCH) and 1,3-dibromo-5,5- dimethylhydantoin (DBH) were used as effective oxidizing agents for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild conditions at room temperature with good to excellent yields.
- Zolfigol, Mohammad Ali,Nasr-Isfahani, Hossein,Mallakpour, Shadpour,Safaiee, Maliheh
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p. 761 - 764
(2007/10/03)
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- Remarkable effects of titanium tetrachloride in diastereoselective aza Diels-Alder cycloaddition: Synthesis of (S)-piperazic acid
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Titanium tetrachloride-mediated aza Diels-Alder cycloaddition using a chiral diene and an aza dienophile proceeds in highly diastereoselective manner to form a dehydropiperazic acid derivative in high yield, and diastereoselectivity of the reaction depends on the quantity of titanium tetrachloride.
- Makino, Kazuishi,Henmi, Yoshiaki,Terasawa, Makiko,Hara, Osamu,Hamada, Yasumasa
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p. 555 - 558
(2007/10/03)
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- Silica sulfuric acid/NaNO2 as a novel heterogeneous system for the oxidation of urazoles under mild conditions
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Neat chlorosulfonic acid reacted with silica gel to give silica sulfuric acid (I) in which sulfuric acid functions immobilized on the surface of silica gel via covalent bonding. Urazoles and bis-urazoles can be readily converted to their corresponding triazolinediones with a combination of silica sulfuric acid (I), wet SiO2 and sodium nitrite in dichloromethane at room temperature.
- Zolfigol, Mohammad Ali,Chehardoli, Gholamabbas,Mallakpour, Shadpour E.
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p. 833 - 841
(2007/10/03)
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- 1,4-Diazabicyclo[2.2.2]octane 1,4-bis(oxide)-bis(hydrogen peroxide)/MClx as a novel heterogeneous system for the oxidation of urazoles under mild conditions
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A combination of inorganic hydrolyzable chloride salts and 1,4-diazabicyclo[2.2.2]octane 1,4-bis(oxide)-bis(hydrogen peroxide), DABCO-DNODP, in the presence of wet SiO2 is used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with good to excellent yields.
- Zolfigol, Mohammad Ali,Salehi, Peyman,Mallakpour, Shadpour E.,Torabi, Mehdi
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p. 1673 - 1674
(2007/10/03)
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- Reactivity of 4-R-1,2,4-triazoline-3,5-diones towards nitrone spin-traps: Spectral study of the reaction with α-phenyl- n-t-butyl nitrone (PBN)
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The reaction of 4-R-1,2,4-triazoline-3,5-diones (R=CH3, C 6H5) with a nitrone spin-trap, phenyl-t-butyl nitrone (PBN) was investigated. Unlike the previously studied reaction with dimethyl pyrroline N-oxide (DMPO), if PBN is used as spin-trap, several spin-adducts but not the expected one were evidenced by EPR spectra. Therefore a spectral study using combined spectral methods (UV-VIS, IR-TF, NMR, EPR) was performed. The data provide evidence for an electron-transfer process from the nitrone to the triazolindione, with subsequent reactions of the radical-ions, leading to RTAD polymers. Kinetic studies in acetonitrile and chloroform based on visible spectra evidence a reaction intermediate, presumably a charge transfer complex, as the precursor of the electron-transfer. Corroborating spectral data on the time evolution of the reaction mixture and products allow to propose a possible reaction mechanism.
- Volanschi, Elena,Alstanei, Ana Maria,Hornoiu, Cristian,Carles, Micheline,Aycard, Jean-Pierre
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- Efficient and convenient oxidation of urazoles to their corresponding triazolinediones under solvent-free conditions
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Urazoles are oxidized to their corresponding triazolinediones in excellent yields with potassium dichromate in the presence of aluminium chloride under solvent-free conditions.
- Mohammadpoor-Baltork, Iraj,Sadeghi, Majid M.,Mallakpour, Shadpour E.,Hajipour, Abdol Reza,Adibi, Abol-Hassan
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p. 3445 - 3448
(2007/10/03)
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- Oxidation of urazoles to triazolinediones under solvent-free conditions using permanganate and alumina-supported permanganate
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Treatment of urazoles with potassium permanganate leads to a simple and mild oxidation reaction, which produces triazolinediones. The reaction is conducted under solvent-free conditions and triazolinediones can be isolated in good to high yields by a simple work-up procedure. The reaction with alumina-supported permanganate enhances the rate and yield.
- Hajipour, Abdol R.,Mallakpour, Shadpour E.,Zolfigol, Mohammad A.,Adibi
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p. 2425 - 2427
(2007/10/03)
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- Trichloroisocyanuric acid as a novel oxidizing agent for the oxidation of urazoles under both heterogeneous and solvent free conditions
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Trichloroisocyanuric acid was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under both heterogeneous and also solvent free conditions with excellent yields at room temperature.
- Zolfigol, Mohammad Ali,Madrakian, Elaheh,Ghaemi, Ezat,Mallakpour, Shadpour
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p. 1633 - 1636
(2007/10/03)
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- Unusual sulfur chemistry in the thermal reaction of sultene and thiophene endoperoxide sulfur donors with cyclic alkynes: Reversible formation of a persistent thiirenium ion and trapping of a thiirene by [4 + 2] cycloaddition
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The highly reactive cyclooctyne 2b serves as sulfur acceptor for both sulfur donors, namely the sultene 1A and thiophene endoperoxide 1B to afford sulfur-transfer products. With the acid-activated sultene 1A, the persistent thiirenium ion 3Ab is formed, which has allowed the direct observation of the initial sulfur-transfer adduct. On treatment with base, the thiirenium ion 3Ab reverts quantitatively to the cyclooctyne and sultene, whereas in neutral media it rearranges to the diene 6Ab. The rearrangement to the diene 6Ab, as well as the formation of spirocyclic adduct 6Ac in the reaction with dithiocyclononyne 2c, is proposed to proceed through a carbene mechanism. In the reaction of the cyclooctyne 2b with thiophene endoperoxide 1B, a thiirene is formed through sulfur transfer by an intermediary oxathiirane derived from the thiophene endoperoxide; as final product, the episulfide (R*,R*,R*)-3Bb is produced diastereoselectively by immediate [4 + 2] cycloaddition of the thiirene with the heterodiene 4B.
- Adam, Waldemar,Bosio, Sara G.,Froehling, Bettina,Leusser, Dirk,Stalke, Dietmar
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p. 8316 - 8320
(2007/10/03)
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- Silica chloride/NaNO2 as a novel heterogeneous system for the oxidation of urazoles under mild conditions
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Urazoles and bis-urazoles can be converted in excellent yields to their corresponding triazolinediones, with a combination of silica chloride (I), wet SiO2 and sodium nitrite in dichloromethane at room temperature.
- Zolfigol, Mohammad Ali,Torabi, Mehdi,Mallakpour, Shadpour E
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p. 8381 - 8384
(2007/10/03)
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- Oxidation of urazoles to triazolinediones with benzyltriphenylphosphonium peroxymonosulfate under solvent-free conditions
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Benzyltriphenylphosphonium peroxymonosulfate (PhCH2Ph3PHSO5) in the presence of A1Cl3 was used as an effective oxidizing reagent for the oxidation of urazoles to their corresponding triazolinediones in high yields under solvent-free conditions.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Adibi, Hadi
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p. 164 - 165
(2007/10/03)
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- Oxidation of urazoles under mild and heterogeneous conditions with KHSO5 and NaNO2
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A combination of potassium monopersulfate and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with excellent yields.
- Zolfigol,Bagherzadeh,Chehardoli,Mallakpour
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p. 1149 - 1154
(2007/10/03)
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- Oxidation of urazoles to their corresponding triazolinediones under mild and heterogeneous conditions via in situ generation of NO+IOx-
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A combination of periodic or iodic acids and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with good yields.
- Zolfigol,Chehardoli,Shirini,Mallakpour,Nasr-Isfahani
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p. 1965 - 1970
(2007/10/03)
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- An efficient method for the oxidation of urazoles with [NO+·crown· H(NO3)2-]
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An ionic complex has been obtained from N2O4 in the presence of the macrocyclic polyether 18-crown-6. This crystalline compound was used as an effective oxidizing agent for the oxidation of urazoles to their corresponding triazolinediones at room temperature with excellent yields.
- Zolfigol, Mohammad Ali,Zebarjadian, Mohammad Hassan,Chehardoli, Gholamabbas,Mallakpour, Shadpour E,Shamsipur, Mojtaba
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p. 1627 - 1629
(2007/10/03)
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- Oxidation of urazoles via in situ generation of Cl+ by using N,N,2,3,4,5,6-heptachloroaniline or a UHP/MCln system under mild conditions
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A combination of inorganic hydrolysable chloride salts and UHP (hydrogen peroxide-urea complex) in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions in good to excellent yields. Oxidation of urazoles and bis-urazoles also occurred with N,N,2,3,4,5,6-heptachloroaniline. The in situ generation of Cl+ appears to be required for the oxidation of urazoles using these reagents.
- Zolfigol,Bagherzadeh,Chehardoli,Mallakpour,Mamaghani
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p. 390 - 393
(2007/10/03)
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- Oxidation of urazoles to their corresponding triazolinediones under mild and heterogeneous conditions
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A combination of sodium hydrogen sulfate and sodium nitrite in the presence of wet SiO2 is used as an effective oxidizing agent for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones at room temperature with excellent yields.
- Zolfigol,Mallakpour,Madrakian,Ghaemi
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p. 308 - 310
(2007/10/03)
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- An efficient method for the oxidation of urazoles under mild and heterogeneous conditions
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A combination of inorganic acidic salts or silica gel-supported inorganic acids and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogenous conditions in good yields. Silica gel supported nitric acid and ceric ammonium nitrate (CAN) are also capable of effecting these oxidations in the absence of sodium nitrite in moderate to good yields. Mg(HSO4)2 is a superior to all the aforementioned reagents in convenience, yield and purity of the isolated triazolinediones.
- Zolfigol, Mohammad Ali,Borazjani, Maryam Kiany,Mallakpour, Shadpour E.,Nasr-Isfahani, Hossein
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p. 2573 - 2585
(2007/10/03)
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- A convenient method for the oxidation of urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with sodium nitrate and oxalic dihydrate
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A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones at room temperature with good yields.
- Zolfigol, Mohammad Ali,Mallakpour, Shadpour E.
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p. 4061 - 4069
(2007/10/03)
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- Electrosynthesis of cyclic α-carbonylazo compounds. Chemical stability of the electrogenerated dienophiles and in situ trapping of dienes
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Dienophilic cyclic α-carbonylazo compounds were prepared electrochemically by oxidation of the corresponding hydrazino compounds using a flow cell fitted with a graphite felt anode in acidic methanol or acetonitrile. The instability of these compounds in methanol was first studied. In situ Diels-Alder additions of these electrogenerated dienophiles and various dienes were performed in relatively good yields in acidic methanol or acetonitrile.
- Lorans,Hurvois,Moinet
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p. 807 - 813
(2007/10/03)
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- Synthesis of labelled 1-azafagomine
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(3,4-trans-4,5-trans)-4,5-Dihydroxy-3-(hydroxymethyl)hexahydro-(3- 13C)pyridazine (azafagomine, 1a) was synthesised in 7 steps starting from (2-13C) malonic acid 5a through conversion to pentadienoic acid and Diels-Alder reaction with 4-phenyl-1,2,4-triazole-3,5-dione, reduction, epoxidation, epoxide hydrolysis and deprotection. The Royal Society of Chemistry 1999.
- Hansen, Steen Uldall,Bols, Mikael
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p. 3323 - 3325
(2007/10/03)
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- 1-Azafagomine: A hydroxyhexahydropyridazine that potently inhibits enzymatic glycoside cleavage
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(3,4-trans-4,5-trans)-4,5-dihydroxy-3-hydroxymethylhexahydropyridazine (16) was synthesized in four steps from 2,4-pentadienol (22) and 4-phenyltriazolin-3,5-dione (18) in an overall yield of 32%. In the first step a Diels Alder reaction between 18 and 22 gave (±)-2-hydroxymethyl-8-phenyl-1,6,8-triazabicyclo[4.3.0]non-3-ene-7,9-dione (23c) in 88% yield. Epoxidation of 23c with trifluoromethyl(methyl)dioxirane, generated in situ, gave the trans epoxide 24c in 62% yield. Hydrolysis of the epoxide with perchloric acid gave stereoselectively (2,3-trans-3,4-trans)-3,4-dihydroxy-2-hydroxymethyl-8-phenyl-1,6,8-triazabicy clo[4.3.0]-nonane-7,9-dione (26) in 73% yield. In the fourth and final step, hydrazinolysis of 26 gave 16 in 84% yield. Pyridazine 16 was found to be a potent inhibitor of χ-and β-glucosidase, isomaltase and glycogen phosphorylase, while galactosidases and χ-mannosidase were not inhibited. The inhibition of β-glucosidase is independent of pH, and was found to be due to unprotonated 16.
- Bols, Mikael,Hazell, Rita G.,Thomsen, Ib B.
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p. 940 - 947
(2007/10/03)
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- Synthetic studies on 4,5-dihydro-3H-1,2,4-triazole-3,5-diones bearing fluorogenic residues at N-4
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A number of fluorescent 4,5-dihydro-3H-1,2,4-triazole-3,5-diones have been made. Intra-inter-electrophilic substitution by the triazoledione moiety on the activated naphthalene ring of 4-[6-(5-dimethylamino-1-naphthylsulfonamido)hexyl]-4,5-dihydro-3H-1,2,4- triazole-3,5-dione 4a3 leads to rapid decomposition. The dienophilicity of the triazoledione moiety in 4-pyren-1-yl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione 4d is dramatically lowered by steric shielding. Insertion of a three-carbon spacer unit into the latter compound, to give the 3-pyren-1-ylpropyl analogue 4e, affords a valuable fluorogenic reagent for the analysis of trace levels of 1,3-dienes. Powdered barium manganate is shown to be an excellent solid-phase oxidant for conversion of urazoles into 1,2,4-triazole-3,5-diones.
- Read, Gordon,Richardson, Nigel R.
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p. 167 - 174
(2007/10/03)
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