- Palladium(II)-catalyzed oxidation of l-tryptophan by hexacyanoferrate(III) in perchloric acid medium: A kinetic and mechanistic approach
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The catalytic effect of palladium(II) on the oxidation of l-tryptophan by potassium hexacyanoferrate(III) has been investigated spectrophotometrically in aqueous perchloric acid medium. A first order dependence in [hexacyanoferrate(III)] and fractional-first order dependences in both [l-tryptophan] and [palladium(II)] were obtained. The reaction exhibits fractional-second order kinetics with respect to [H +]. Reaction rate increased with increase in ionic strength and dielectric constant of the medium. The effect of temperature on the reaction rate has also been studied and activation parameters have been evaluated and discussed. Initial addition of the reaction product, hexacyanoferrate(II), does not affect the rate significantly. A plausible mechanistic scheme explaining all the observed kinetic results has been proposed. The final oxidation products are identified as indole-3-acetaldehyde, ammonium ion and carbon dioxide. The rate law associated with the reaction mechanism is derived.
- Fawzy, Ahmed
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- Modulating weak interactions for molecular recognition: A dynamic combinatorial analysis for assessing the contribution of electrostatics to the stability of CH-π bonds in water
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Electrostatic and charge-transfer contributions to CH-π complexes can be modulated by attaching electron-withdrawing substituents to the carbon atom. While clearly stabilizing in the gas phase, the outcome of this chemical modification in water is more difficult to predict. Herein we provide a definitive and quantitative answer to this question employing a simple strategy based on dynamic combinatorial chemistry.
- Jiménez-Moreno, Ester,G?mez, Ana M.,Bastida, Agatha,Corzana, Francisco,Jiménez-Oses, Gonzalo,Jiménez-Barbero, Jesús,Asensio, Juan Luis
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- 11-Step Total Synthesis of Araiosamines
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A concise route to a small family of exotic marine alkaloids known as the araiosamines has been developed, and their absolute configuration has been assigned. The dense array of functionality, high polarity, and rich stereochemistry coupled with equilibrating topologies present an unusual challenge for chemical synthesis and an opportunity for innovation. Key steps involve the use of a new reagent for guanidine installation, a remarkably selective C-H functionalization, and a surprisingly simple final step that intersects a presumed biosynthetic intermediate. Synthetic araiosamines were shown to exhibit potency against Gram-positive and -negative bacteria despite a contrary report of no activity.
- Tian, Maoqun,Yan, Ming,Baran, Phil S.
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- Flavin-photosensitized production of indole-3-acetaldehyde from tryptophan
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Photochemical reaction of tryptophan with flavin was performed under anaerobic condition to give indole-3-acetaldehyde as a major product.
- Koshiba,Yamauchi,Matsuyama,Miyakado,Sori,Sato
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- Indolyl-3-acetaldoxime dehydratase from the phytopathogenic fungus Sclerotinia sclerotiorum: Purification, characterization, and substrate specificity
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The purification and characterization of indolyl-3-acetaldoxime dehydratase produced by the plant fungal pathogen Sclerotinia sclerotiorum is described. The substrate specificity indicates that it is an indolyl-3-acetaldoxime dehydratase (IAD, EC 4.99.1.6), which catalyzes transformation of indolyl-3-acetaldoxime to indolyl-3-acetonitrile. The enzyme showed Michaelis-Menten kinetics and had an apparent molecular mass of 44 kDa. The amino acid sequence of IAD, determined using LC-ESI-MS/MS, identified it as the protein SS1G-01653 from S. sclerotiorum. IADSs was highly homologous (84% amino acid identity) to the hypothetical protein BC1G-14775 from Botryotinia fuckeliana B05.10. In addition, similarity to the phenylacetaldoxime dehydratases from Gibberella zeae (33% amino acid identity) and Bacillus sp. (20% amino acid identity) was noted. The specific activity of IADSs increased about 17-fold upon addition of Na2S2O4 under anaerobic conditions, but in the absence of Na2S2O 4 no significant change was observed, whether aerobic or anaerobic conditions were used. As with other aldoxime dehydratases isolated from microbes, the role of IADSs in fungal plant pathogens is not clear, but given its substrate specificity, it appears unlikely that IADSs is a general xenobiotic detoxifying enzyme.
- Pedras, M. Soledade C.,Minic, Zoran,Thongbam, Premila D.,Bhaskar, Vangala,Montaut, Sabine
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- A Soluble Protein Factor from Chinese Cabbage Converts Indole-3-acetaldoxime to IAA
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A soluble enzyme preparation from Chinese cabbage seedlings (Brassica campestris ssp. pekinensis) which catalyses the conversion of indole-3-acetaldoxime (IAOX) to IAA was partially purified by ion exchange chromatography.After purification enzyme activity was stable for more than 6 hr.Substrate kinetics showed a Km value of 50 μM; the pH optimum was 7.The conversion of IAOX to IAA was increased by NAD, NADP or FAD, but none of them seemed to be a preferential co-substrate.Besides IAA some labelled indole-3-acetaldehyde (IAALD) could be extracted from the reaction mixture.Addition of unlabelled IAALD at 100 nmol/ml led to a significant inhibition of IAA formation while some label accumulated in the aldehyde.Indole-3-acetonitrile was never detected as a reaction product.The results are compared with those from earlier in vivo experiments and are discussed in view of their significance for IAA biosynthesis in the Brassicaceae.Key Word Index - Brassica campestris ssp. pekinensis; Cruciferae; Chinese cabbage; indole-3-acetaldoxime; indole-3-acetaldehyde; IAA biosynthesis.
- Helmlinger, Juergen,Rausch, Thomas,Hilgenberg, Willy
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- S -indole benzamide derivative as well as preparation method and application thereof
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S - Indole benzamide derivatives as well as a preparation method and application thereof relate to the technical field of pharmacy. The derivative has a structural formula. The specific preparation method comprises the following steps: taking indole as a starting raw material and performing acylation reaction. Reaction, oxidation reaction, (R)- (+) -tert-butylsulfenamide asymmetric synthesis reaction, hydrolysis reaction and acylation reaction to give the target product. By means of the method, a novel antiviral drug with a development prospect can be obtained, and the yield is high.
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- Towards the Sarpagine-Ajmaline-Macroline Family of Indole Alkaloids: Enantioselective Synthesis of an N-Demethyl Alstolactone Diastereomer
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the strategy involving the use of functionalized tetrahydro-6H-cycloocta[b]indol-6-one is reported as a key intermediate for synthesis of members of the sarpagine-ajmaline-macroline family of monoterpene indole alkaloids. The desired tricycle was synthesized through the following key steps: 1) Evans’ syn-selective aldolization; 2) Liebeskind–Srogl cross-coupling using the phenylthiol ester of 3-chloropropanoic acid as a surrogate of acrylic thioester for the synthesis of 2,3-disubstituted indoles; and 3) ring-closing metathesis (RCM) for the formation of the eight-membered ring. An N-allylation followed by intramolecular 1,4-addition was planned for synthesis of the vobasine class of natural products. However, attempted cyclizations under a diverse set of conditions involving anionic, radical, and organopalladium/organonickel species failed to produce the bridged ring system. On the other hand, esterification of the pendant primary alcohol function with acetoacetic acid, followed by intramolecular Michael addition, afforded the desired tetracycle with excellent diastereoselectivity. Subsequent functional group manipulation and transannular cyclization of the amino alcohol afforded the N(1)-demethyl-3,5-diepi-alstolactone. We believe that the same synthetic route would afford the alstolactone should the amino alcohol with appropriate stereochemistry be used as the starting material.
- Dagoneau, Dylan,Wang, Qian,Zhu, Jieping
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supporting information
p. 4866 - 4873
(2020/04/15)
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- Stereospecific access to bridged [n.2.1] skeletons through gold-catalyzed tandem reaction of indolyl homopropargyl amides
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An efficient gold-catalyzed anti-Markovnikov cycloisomerization-initiated tandem reaction of Boc-protected indole tethered homopropargyl amides has been achieved. This method delivers a wide range of valuable bridged aza-[n.2.1] skeletons (n = 3–7) at room temperature with high diastereoselectivity and enantioselectivity by a chirality-transfer strategy. Moreover, the gold-catalyzed tandem reaction of homopropargyl alcohol is also achieved to produce the bridged oxa-[3.2.1] skeleton.
- Tan, Tong-De,Zhu, Xin-Qi,Jia, Mei,Lin, Yongjia,Cheng, Jun,Xia, Yuanzhi,Ye, Long-Wu
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supporting information
p. 1309 - 1312
(2019/11/26)
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- Design, synthesis and evaluation of novel (S)-tryptamine derivatives containing an allyl group and an aryl sulfonamide unit as anticancer agents
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A series of (S)-tryptamine derivatives containing an allyl group and an aryl sulfonamide unit were designed, synthesized and evaluated for their potential application as anticancer agents. The structures of the synthesized compounds were characterized by 1H NMR, 13C NMR and ESI-MS spectral analyses. The target compounds were evaluated for their in vitro cytotoxicity against HepG2, HeLa, CNE1 and A549 human cancer cell lines. Some of the synthesized compounds showed moderate to good anticancer activities against four selected cancer cell lines, among of which 6ag was found to be the most active analogue possessing IC50 values 16.5–18.7 μM. Further mechanism studies revealed that compound 6ag could significantly induce HepG2 cell cycle arrest at G1 phase, promote cell apoptosis, and inhibit the colony formation as well.
- Guo, Zhenbo,Xu, Yiming,Peng, Yujie,Haroon ur Rashid,Quan, Wei,Xie, Peng,Wu, Lichuan,Jiang, Jun,Wang, Lisheng,Liu, Xu
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p. 1133 - 1137
(2019/03/06)
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- Efficient Synthesis of the Peptide Fragment of the Natural Depsipeptides Jaspamide and Chondramide
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A new method for the synthesis of the tripeptide part of the jaspamide and chondramide alkaloids using a Ugi reaction was developed. The reported approach is considerably shorter than all literature syntheses of the peptide parts of these natural products. A family of peptides with different substituents at the 2-position of the indole moiety was prepared to open up access to analogues of these natural products.
- Zarezin, Danil P.,Shmatova, Olga I.,Kabylda, Adil M.,Nenajdenko, Valentine G.
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p. 4716 - 4722
(2018/09/10)
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- Mechanistic Studies on Tryptophan Lyase (NosL): Identification of Cyanide as a Reaction Product
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Tryptophan lyase (NosL) catalyzes the formation of 3-methylindole-2-carboxylic acid and 3-methylindole from l-tryptophan. In this paper, we provide evidence supporting a formate radical intermediate and demonstrate that cyanide is a byproduct of the NosL-catalyzed reaction with l-tryptophan. These experiments require a major revision of the NosL mechanism and uncover an unanticipated connection between NosL and HydG, the radical SAM enzyme that forms cyanide and carbon monoxide from tyrosine during the biosynthesis of the metallo-cluster of the [Fe-Fe] hydrogenase.
- Bhandari, Dhananjay M.,Fedoseyenko, Dmytro,Begley, Tadhg P.
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supporting information
p. 542 - 545
(2018/01/26)
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- Rapid One-Pot Access to Unique 3,4-Dihydrothiopyrano[3,4-b]indol-1(9H)-imines via Bi(OTf)3-Catalysed Tandem Friedel–Crafts Alkylation/Thia-Michael Addition
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A highly efficient and atom economical one-pot annulation strategy for novel tetrahydrothiopyrano[3,4-b]indoles is presented. This protocol involves a Bi(OTf)3 catalyzed tandem Friedel–Crafts alkylation and intramolecular thia-Michael addition reactions to furnish target molecules in an efficient manner. The method works effectively on substrates with unprotected indoles and also it is successfully employed to make tetrahydrothiepino[3,4-b]indoles. The scaffolds synthesized are diverse and first of the kind. The reaction is practically simple with broad substrate scope and vast functional group compatibility.
- Dethe, Dattatraya H.,Boda, Vijay Kumar,Mandal, Anupam
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p. 5417 - 5421
(2018/10/20)
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- Relay Catalysis of Bismuth Trichloride and Byproduct Hydrogen Bromide Enables the Synthesis of Carbazole and Benzo[α]carbazoles from Indoles and α-Bromoacetaldehyde Acetals
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Benzo[α]carbazoles were synthesized from 2-phenylindoles and α-bromoacetaldehyde using bismuth trichloride as a catalyst. The reaction was triggered by a bismuth trichloride-catalyzed Friedel-Crafts alkylation of these two precursors, which provided a tryptaldehyde intermediate that underwent intramolecular olefination to form the final product. Interestingly, the HBr byproduct generated in the upstream step of the reaction catalyzed the following downstream reaction steps, thus creating a byproduct-participated relay catalytic process. Motivated by this mechanism, we developed a three-component reaction of indole, α-bromoacetaldehyde acetal, and 1,3-dicarbonyl compounds. This study offers a straightforward method for synthesizing substituted carbazoles. (Figure presented.).
- Wu, Fengtian,Huang, Wenbo,Yiliqi,Yang, Jian,Gu, Yanlong
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p. 3318 - 3330
(2018/08/01)
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- BIS-HETEROARYL DERIVATIVES AS MODULATORS OF PROTEIN AGGREGATION
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The present invention relates to certain bis-heteroaryl compounds, pharmaceutical compositions containing them, and methods of using them, including methods for preventing, reversing, slowing, or inhibiting protein aggregation, and methods of treating diseases that are associated with protein aggregation, including neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Lewy body disease, Parkinson's disease with dementia, fronto- temporal dementia, Huntington's Disease, amyotrophic lateral sclerosis, and multiple system atrophy, and cancer including melanoma.
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Paragraph 0144
(2017/02/24)
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- Bicyclic Guanidine Catalyzed Asymmetric Tandem Isomerization Intramolecular-Diels-Alder Reaction: The First Catalytic Enantioselective Total Synthesis of (+)-alpha-Yohimbine
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Hydroisoquinoline derivatives were prepared in moderate to good enantioselectivities via a bicyclic guanidine-catalyzed tandem isomerization intramolecular-Diels-Alder (IMDA) reaction of alkynes. With this synthetic method, the first enantioselective synthesis of (+)-alpha-yohimbine was completed in 9 steps from the IMDA products.
- Feng, Wei,Jiang, Danfeng,Kee, Choon-Wee,Liu, Hongjun,Tan, Choon-Hong
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supporting information
p. 390 - 394
(2016/05/19)
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- α-Amino Acid-Isosteric α-Amino Tetrazoles
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The synthesis of all 20 common natural proteinogenic and 4 otherα-amino acid-isosteric α-amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5-tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection chemistries. The tetrazole group is bioisosteric to the carboxylic acid and is widely used in medicinal chemistry and drug design. Surprisingly, several of the common α-amino acid-isosteric α-amino tetrazoles are unknown up to now. Therefore a rapid synthetic access to this compound class and non-natural derivatives is of high interest to advance the field.
- Zhao, Ting,Kurpiewska, Katarzyna,Kalinowska-T?us?cik, Justyna,Herdtweck, Eberhardt,D?mling, Alexander
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p. 3009 - 3018
(2016/03/26)
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- ENANTIOSELECTIVE SYNTHESES OF HETEROYOHIMBINE NATURAL PRODUCT INTERMEDIATES
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Enantioselective syntheses of cis- and trans-bicyclic dihydropyran compounds, and other intermediates, en route to heteroyohimbine alkaloids.
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Paragraph 00059; 00060
(2016/11/21)
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- Enantioselective syntheses of heteroyohimbine natural products: A unified approach through cooperative catalysis
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Alstonine and serpentine are pentacyclic indoloquinolizidine alkaloids (referred to as "anhydronium bases") containing three contiguous stereocenters. Each possesses interesting biological activity, with alstonine being the major component of a plant-based remedy to treat psychosis and other nervous system disorders. This work describes the enantioselective total syntheses of these natural products with a cooperative hydrogen bonding/enamine-catalyzed Michael addition as the key step. The enantioselective total syntheses of the natural products alstonine and serpentine are presented. They proceed through a sequence with a cooperative hydrogen bonding/enamine-catalyzed Michael addition as the key step.
- Younai, Ashkaan,Zeng, Bi-Shun,Meltzer, Herbert Y.,Scheidt, Karl A.
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supporting information
p. 6900 - 6904
(2015/06/08)
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- A facile approach to tryptophan derivatives for the total synthesis of argyrin analogues
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A facile route has been established for the synthesis of indole-substituted (S)-tryptophans from corresponding indoles, which utilizes a chiral auxiliary-facilitated Strecker amino acid synthesis strategy. The chiral auxiliary reagents evaluated were (S)-methylbenzylamine and related derivatives. To illustrate the robustness of the method, eight optically pure (S)-tryptophan analogues were synthesized, which were subsequently used for the convergent synthesis of a potent antibacterial agent, argyrin A and its analogues.
- Chen, Chou-Hsiung,Genapathy, Sivaneswary,Fischer, Peter M.,Chan, Weng C.
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p. 9764 - 9768
(2015/01/09)
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- Facile one-pot synthesis of tetrahydroisoquinolines from amino acids via hypochlorite-mediated decarboxylation and Pictet-Spengler condensation
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A convenient method for oxidative decarboxylation of α-amino acids is presented. The aldehyde products may be isolated or converted to tetrahydroisoquinolines by addition of dopamine via Pictet-Spengler reaction. Racemic products are generated by phosphate buffer >300 mM to maximize regioselectivity. (S)-Enantiomer products are generated by norcoclaurine synthase reaction in maleic acid buffer to minimize chemical background reaction.
- Maresh, Justin J.,Crowe, Sean O.,Ralko, Arthur A.,Aparece, Mark D.,Murphy, Casey M.,Krzeszowiec, Mark,Mullowney, Michael W.
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p. 5047 - 5051
(2015/01/09)
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- Characterization of a new enzyme oxidizing ω-amino group of aminocarboxyric acid, aminoalcohols and amines from Phialemonium sp. AIU 274
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A new enzyme exhibiting oxidase activity for ω-aminocarboxylic acids, ω-aminoalcohols, monoamines and diamines was found from a newly isolated fungal strain, Phialemonium sp. AIU 274. The enzyme also oxidized aromatic amines, but not l- and d-amino acids. The Vmax/Km value for hexylamine was higher than those for 6-aminoalcohol and 6-aminhexanoic acid in the aliphatic C6 substrates. In the aliphatic amines, the higher Vmax/Km values were obtained by the longer carbon chain amines. Thus, the enzyme catalyzed oxidative deamination of the ω-amino group in a wide variety of the ω-amino compounds and preferred medium- and long-chain substrates. The oxidase with such broad substrate specificity was first reported here. The enzyme contained copper, and the enzyme activity was strongly inhibited by isoniazid, iproniazid and semicarbazide, but not by clorgyline and pargyline. The enzyme was composed of two identical subunits of 75 kDa.
- Isobe, Kimiyasu,Sasaki, Tomoko,Aigami, Yuusuke,Yamada, Miwa,Kishino, Shigenobu,Ogawa, Jun
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- SMALL MOLECULE INDUCERS OF GDNF AS POTENTIAL NEW THERAPEUTICS FOR NEUROPSYCHIATRIC DISORDERS
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The invention provides a compound having the structure (I), wherein A is a substituted or unsubstituted ring; Z is present or absent and when present is (II), wherein n is 0, 1, 2, 3, or 4; Y is -(CR11R12)-, -NH(CR11R12)- or -O(CR11R12)- wherein R11 and R12 are each hydrogen or combine to form a carbonyl; and wherein R1 to R10 are herein as described.
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Page/Page column 101; 102
(2013/03/26)
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- Metal-free, mild, nonepimerizing, chemo- and enantio- or diastereoselective N-alkylation of amines by alcohols via oxidation/imine-iminium formation/reductive amination: A pragmatic synthesis of octahydropyrazinopyridoindoles and higher ring analogues
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A mild step and atom-economical nonepimerizing chemo- and enantioselective N-alkylating procedure has been developed via oxidation/imine-iminium formation/reduction cascade using TEMPO-BAIB-HEH-Bronsted acid catalysis in DMPU as solvent and a stoichiometric amount of amine. The optimized conditions were further extended for the nonenzymatic kinetic resolution of the chiral amine thus formed under nonenzymatic in situ hydrogen-transfer conditions using VAPOL-derived phosphoric acid (VAPOL-PA) as the Bronsted acid catalyst. The enantioselective cascade of the presented reaction was successfully utilized in the synthesis of octahydropyrazinopyridoindole and its higher ring analogues.
- Khan, Imran A.,Saxena, Anil K.
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p. 11656 - 11669
(2014/01/06)
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- Lathyrus cicera copper amine oxidase reactions with tryptamine
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Lathyrus cicera copper amine oxidase (LCAO) rapidly formed the typical Cu(I)-TPQ semiquinone UV-visible spectrum, identical to that formed by other substrates, upon O2 exhaustion by turnover with excess tryptamine. A new band at 630 nm formed more slowly, with intensity dependent on aldehyde and H2O2 concentrations. On prolonged incubation, all bands decayed in parallel, together with loss of enzymatic activity. The blue color disappeared on addition of KCN, a Cu(I) stabilizing agent, while the intensity of the radical visible bands increased. This shows that the 630 nm absorbing species is a Cu(II) derivative, as confirmed by the unchanged intensity of the EPR spectrum of the frozen blue solution from that of the native protein. Rapid kinetics experiments showed that this species derives from a reduced form of the protein, plus aldehyde and H2O2 and that it is not in dynamic equilibrium with the radical. Given the similar population of the semiquinone radical with all substrates, it is possible that the reaction with aldehyde and H2O2 occurs in all cases although substrates lacking the indole group only produce the Cu(I)-semiquinone band. The radical participation to the catalytic activity is demonstrated by the observation that its relative population (controlled by the pH) parallels changes in the reoxidation rate constant, while the 630 nm absorbing species is implied in the inactivation process, which depends on H2O2 and aldehyde concentration. The results of the paper are consistent with half-of-the-site reactivity, i.e. the two subunits of LCAO are kinetically and spectroscopically distinct from each other.
- Pietrangeli, Paola,Bellelli, Andrea,Fattibene, Paola,Mondovì, Bruno,Morpurgo, Laura
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experimental part
p. 33 - 39
(2012/07/13)
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- Development of rationally designed DNA N6 adenine methyltransferase inhibitors
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A series of bisubstrate inhibitors for DNA N6 adenine methyltransferase (Dam) have been synthesized by linking an amine analogue of S-adenosylmethionine to an aryl moiety designed to probe the binding pocket of the DNA adenine base. An initial structure-activity relationship study has identified substituents that increase inhibitor potency to the ~10 μM range and improve selectivity against the human cytosine methyltransferase Dnmt1.
- Hobley, Gerard,McKelvie, Jennifer C.,Harmer, Jenny E.,Howe, Jason,Oyston, Petra C.F.,Roach, Peter L.
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supporting information; experimental part
p. 3079 - 3082
(2012/06/17)
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- The catalytic potential of Coptis japonica NCS2 revealed - Development and utilisation of a fluorescamine-based assay ETI
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The versatility and potential of a norcoclaurine synthase (NCS) from Coptis japonica NCS2 has been investigated, together with the development and application of a novel fluorescence-based high-throughput assay using nearly forty amines/aldehydes. The stereocontrol exerted by CjNCS2 on selected non-natural substrates has been determined, where the tetrahydroisoquinolines (THIAs) were formed as the (1S)-isomer in >95% ee, as observed with the natural product norcoclaurine. Docking calculations involving THIA mechanism intermediates, utilising the reported Thalictrum flavum NCS X-ray crystallographic structure, were carried out and combined with the CjNCS2 screening results to further understand the mode of action of NCS. These findings suggested that in addition to the key active-site residues K122 and E110, D141 is also mechanistically essential for the enzymatic transformation. The exceptional tolerance of NCS towards aldehyde substrates is furthermore supported by our proposed mechanism in which the aldehydes protrude out of the enzymatic pocket. Copyright
- Pesnot, Thomas,Gershater, Markus C.,Ward, John M.,Hailes, Helen C.
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supporting information
p. 2997 - 3008
(2013/01/15)
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- Microwave-assisted synthesis of 5-substituted 2-aminothiophenes starting from arylacetaldehydes
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An easy three-step pathway for the synthesis of arylacet-aldehydes from the corresponding carboxylic acids in very high yields is described. Their use as precursors of 5-substituted-2-aminothiophenes is illustrated via a microwave-assisted Gewald reaction. This method allows obtaining the expected compounds in a shorter time and with better yields and purities than the classical procedures. Georg Thieme Verlag Stuttgart - New York.
- Revelant, Germain,Dunand, Sandrine,Hesse, Stephanie,Kirsch, Gilbert
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p. 2935 - 2940
(2011/11/01)
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- Deposition of new thia-containing Schiff-base iron (III) complexes onto carbon nanotube-modified glassy carbon electrodes as a biosensor for electrooxidation and determination of amino acids
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Multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate an Fe (III)-Schiff base complex as an electron-transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on filter paper supporting the carbon nanotubes. Second, the electrode surface was modified by casting 100 μL of an Fe (III)-complex solution (0.01 M in ACN). The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and nearly reversible reductive oxidation redox systems with surface confined characteristics. Combinations of unique electronic and electrocatalytic properties of MWCNTs and Fe (III)-Schiff base complexes resulted in a remarkable synergistic augmentation of the response. The electrochemical behavior and stability of the modified electrode in aqueous solutions at pH 1-9 were characterized by cyclic voltammetry. The apparent electron transfer rate constant (Ks) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7 s-1 and 0.55, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of amino acids at an unusually positive potential in acidic solution. They also displayed inherent stability at a wide pH range, fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of amino acids that decreased the effect of interferences in analysis. The linear concentration range, limits of detection (LOD), limits of quantization (LOQ) and relative standard deviation of the proposed sensor for the amino acid detection were 1-55,000, 1.10-13.70, 2.79-27.14 and 1.30-5.11, respectively.
- Saghatforoush, Lotfali,Hasanzadeh, Mohammad,Shadjou, Nasrin,Khalilzadeh, Balal
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experimental part
p. 1051 - 1061
(2011/04/16)
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- The possible production of natural flavours by amino acid degradation
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This work describes the degradation of phenylalanine and tryptophane catalysed by their complexes with Fe(II), Co(II), and Cu(II). The influences of the central atom and of the reaction conditions on the degradation of the amino acids were observed. The necessary condition of the degradation is the possibility of a redox reaction on the central atom between M(II) and M(III). Moreover, the coordination sphere of the central cation of the transition metal must not be sterically shielded. The necessary conditions are fulfilled only in the Fe(II) complexes. The degradation is strictly anaerobic because due to the influence of oxygen, an irreversible oxidation of Fe(II) to Fe(III) proceeds. This reaction results in 5-hydroxy-1H-indol instead of the mixture of the degradation products, such as benzaldehyde, phenylacetaldehyde, and phenylacetic acid. The influence of the temperature on the catabolism is very important because the reaction accelerates with temperature increase. The phenylalanine anion acts as a reducing agent, and Fe(II) is spontaneously reduced to Fe(0). Springer-Verlag 2010.
- Klacanova, Katarina,Fodran, Peter,Rosenberg, Michal
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experimental part
p. 823 - 828
(2011/07/07)
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- Oxidations of N-(3-indoleethyl) cyclic aliphatic amines by horseradish peroxidase: The indole ring binds to the enzyme and mediates electron-transfer amine oxidation
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Although oxidations of aromatic amines by horseradish peroxidase (HRP) are well-known, typical aliphatic amines are not substrates of HRP. In this study, the reactions of N-benzyl and N-methyl cyclic amines with HRP were found to be slow, but reactions of N-(3-indoleethyl) cyclic amines were 2-3 orders of magnitude faster. Analyses of pH-rate profiles revealed a dominant contribution to reaction by the amine-free base forms, the only species found to bind to the enzyme. A metabolic study on a family of congeneric N-(3-indoleethyl) cyclic amines indicated competition between amine and indole oxidation pathways. Amine oxidation dominated for the seven- and eight-membered azacycles, where ring size supports the change in hybridization from sp3 to sp2 that occurs upon one-electron amine nitrogen oxidation, whereas only indole oxidation was observed for the six-membered ring congener. Optical difference spectroscopic binding data and computational docking simulations suggest that all the arylalkylamine substrates bind to the enzyme through their aromatic termini with similar binding modes and binding affinities. Kinetic saturation was observed for a particularly soluble substrate, consistent with an obligatory role of an enzyme-substrate complexation preceding electron transfer. The significant rate enhancements seen for the indoleethylamine substrates suggest the ability of the bound indole ring to mediate what amounts to medium long-range electron-transfer oxidation of the tertiary amine center by the HRP oxidants. This is the first systematic investigation to document aliphatic amine oxidation by HRP at rates consistent with normal metabolic turnover, and the demonstration that this is facilitated by an auxiliary electron-rich aromatic ring.
- Ling, Ke-Qing,Li, Wen-Shan,Sayre, Lawrence M.
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p. 933 - 944
(2008/09/20)
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- INHIBITORS OF PRENYL-PROTEIN TRANSFERASE
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The present invention comprises piperazine/piperazinone-containing compounds having multicyclic ring system substituents on one of the piperazine/piperazinone nitrogens, which inhibit prenyl-protein transferases, including farnesyl-protein transferase and geranylgeranyl-protein transferase type I. Such therapeutic compounds are useful in the treatment of cancer
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(2010/01/21)
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- A modified bait and switch strategy for the generation of esterolytic abzymes using concerted catalytic mechanisms
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Esterolytic abzymes were generated via immunization with a haptenic diphosphonate mounted with two distinct traps actuated by the 'bait and switch' and 'transition-state mimic' concepts. One monoclonal antibody, 12F12, was characterized in detail, and showed significant rate enhancement and unique substrate specificity. Experimental data support that the antibody catalyzes the reactions with a concerted catalytic mechanism.
- Iwabuchi, Yoshiharu,Kurihara, Shinwa,Oda, Motoko,Fujii, Ikuo
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p. 5341 - 5344
(2007/10/03)
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- Oxidation of Alcohols with o-Iodobenzoic Acid (IBX) in DMSO: A New Insight into an Old Hypervalent Iodine Reagent
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The ultracentennial 10-I-4 iodinane oxide IBX (3; o-iodoxybenzoic acid; 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide) represents a new oxidizing reagent that successfully joins to the large family of known oxidants.IBX, in contrast to other valuable oxidants, is inexpensive to prepare and easy to handle, can tolerate moisture and water, and generally gives very good yields.Furthermore, IBX is mild and chemoselective (primary alcohols are converted into aldehydes with no overoxidation to acids; 1,2-diols are converted to α-ketols or α-diketones without oxidative cleavage; amino alcohols are oxidized to amino carbonyls, without protection of the amino group; sensitive heterocycles are not affected; various other functional groups are compatible with IBX oxidation).IBX is versatile (it works in various solvents and it is highly sensitive to temperature variations), and its solutions in DMSO are stable enough to carry out the oxidation reaction easily.
- Frigerio, Marco,Santagostino, Marco,Sputore, Simona,Palmisano, Giovanni
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p. 7272 - 7276
(2007/10/03)
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- Facile synthesis of tryptophaldehyde. Synthesis and structural elucidation of murrayacarine.
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Tryptophaldehyde (indole-3-acetaldehyde) is prepared in two steps from indole-3-acetic acid, via the corresponding N-methoxy N-methyl amide.Tryptophaldehyde reacts with Wittig-Horner reagents without prior protection.Its usefulness is illustrated by short syntheses of paniculidine A and of murrayacarine, two alkaloids from Murraya paniculata.
- Boumendjel, A.,Nuzillard, J. M.,Massiot, G.
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p. 645 - 647
(2007/10/02)
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- Synthesis and Serotonin Binding Site Studies of Some Conformationally Restricted Indolylethylamine Analogues Based on 2-Amino-3-(3'-indolyl)bicyclooctane
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The bicycloannulation reaction between cyclohexanone and indolyl enamines yields trans-3-(cyclic amino)-2-(3'-indolyl)bicyclooctan-5-ones, and these adducts are conformationally restricted analogues of indolylethylamine (tryptamine) which exhibit structure-dependent affinity for the serotonin 5HT2 and 5HT1a receptors.The stereochemistry of the isomeric endo and exo adduct obtained is assigned from the 1H NMR spectra of the specifically deuterated alkenes prepared from the ketones by the Bamford-Stevens reaction.Molecular mechanics calculations indicate that the conformational flexibility of the amino and indolyl groups is restricted through van der Waals interactions with the bridges of the bicyclic unit.These compounds inhibit the binding of ketanserin to 5HT2 sites in mouse cerebrocortical membranes, and the binding of -8-hydroxy-2-(di-n-propylamino)tetralin(-8-OH-DPAT) to 5HT1a sites in mouse hippocampal membranes.The endo compounds are the most potent, and molecular mechanics calculations indicate that these isomers have a less bulky bicyclo bridge proximate to the amine group and more conformational freedom about the Cα-Cβ-N+-H dihedral angle (τ3).In the 5HT2 assay, endo-trans-3-(N-piperidinyl)-2-(3'-indolyl)bicyclooctan-5-one (10a) is the most potent, and endo-trans-3-(N-pyrrolidinyl)-2-(3'-indolyl)bicyclooct-5-ene (12a) is the most potent in the 5HT1a assay.A phenyl-substituted adduct shows the least affinity in these two assays.These data provide insight into the structural differences between the 5HT1a and 5HT2 receptor sites.
- Schlecht, M. F.,Tsarouhtsis, D.,Lipovac, M. N.,Debler, E. A.
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p. 386 - 394
(2007/10/02)
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- Kinetics and mechanism of oxidation of L-tryptophan by peroxomonophosphoric acid
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L-Tryptophan is oxidised by peroxomonophosphoric acid (PMPA) in the limited pH range of 0.0 - 2.5.The dependence on substrate and oxidant is unity each.Dependence on +> suggests H3PO5 as the reacting species.Indole-3-acetaldehyde is one of the products of reaction.A suitable rate law has been proposed.
- Panigrahi, Ganesh P.,Paichha, Ramesh C.
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p. 272 - 273
(2007/10/02)
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- A Convenient One-flask Synthesis of α-Methylenealdehydes from Primary Alcohols
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A convenient one-flask synthesis of α-methylenealdehydes from primary alcohols has been established.
- Takano, Seiichi,Inomata, Kohei,Samizu, Kiyohiro,Tomita, Shun'ichi,Yanase, Masashi,et al.
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p. 1283 - 1284
(2007/10/02)
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- CONVERSION OF INDOLES INTO QUINOLINES THROUGH THE N-1-C-2 FISSION BY SINGLET-OXYGEN AS A MODEL EXPERIMENT OF BIOMIMETIC SYNTHESIS OF QUININE ALKALOIDS
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Photo-oxygenation of indole-3-acetaldehydes (28-30) followed by treatments with dimethyl sulphide and then dilute acetic acid gave 4-acylquinolines (13, 31 and 32), respectively.
- Ihara, Masataka,Noguchi, Kazuharu,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 2109 - 2114
(2007/10/02)
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- PHOTOCHEMICAL REACTION BETWEEN TRYPTOPHAN AND THYMINE
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Irradiation of tryptophan and thymine in aqueous solution produced two photoadducts whose structures were determined by spectral data and X-ray crystallographic analysis.
- Saito, Isao,Sugiyama, Hiroshi,Matsuura, Teruo,Fukuyama, Keiichi,Katsube, Yukiteru
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p. 3243 - 3246
(2007/10/02)
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- OXIDATIVE DECARBOXYLATION OF α-AMINO ACIDS WITH COENZYME PQQ
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Oxidative decarboxylation of α-phenylglycine with coenzyme PQQ was performed catalytically in the presence of CTAB under mild condi- tions to give benzaldehyd and benzoic acid.
- Itoh, Shinobu,Kato, Nobuyuki,Ohshiro, Yoshiki,Agawa, Toshio
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p. 4753 - 4756
(2007/10/02)
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- Synthesis of (-)-Hobartine and Related Indole Alkaloids
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An improved method for obtaining optically pure (S)-(1-p-menthen-8-yl)amine (12) has led to expedient syntheses of two hypothetical biogenetic intermediates on the way (S)-N-(1-p-menthen-8-yl)-2-(3-indolyl)ethylideneamine (4).The latter has been transformed into (-)-hobartine (6) in 64percent yield via stereoselective biomimetic cyclization by treatment with HCOOH.This unambiguous synthesis establishes the hitherto unknown absolute configuration of (-)-hobartine (6).Several model cyclization reactions of N-substituted α-(terpen-8-yl)imine derivatives yielding unsaturated 3-azabicyclononane compounds are described.
- Darbre, Tamis,Nussbaumer, Cornelius,Borschberg, Hans-Juerg
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p. 1040 - 1052
(2007/10/02)
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- PHOTO-OXYGENATION OF INDOLE-3-ACETIC ACIDS AND INDOLE-3-ACETALDEHYDES: BIOMIMETIC CONVERSION OF INDOLES INTO QUINOLINES VIA N1-C2 FISSION
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New conversion of indoles to quinolines via the N1-C2 fission using singlet oxygen reaction was investigated starting from indole-3-acetic acids and indole-3-acetaldehydes.Dye-induced photo-oxydation of indole-3-acetaldehyde derivatives (17 and 18) followed by treatments with dimethyl sulfide and then acetic acid produced 4-formyl- and 4-acetylquinolines (19 and 20), respectively.
- Ihara, Masataka,Noguchi, Kazuharu,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 421 - 424
(2007/10/02)
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