- Redesigning of the cap conformation and symmetry of the diphenylethyne core to yield highly potent pan-genotypic NS5A inhibitors with high potency and high resistance barrier
-
Herein, we report the discovery of several NS5A inhibitors with potency against HCV genotype 1b in the picomolar range. Compounds (15, 33) were of extremely high potency against HCV genotype 1b (EC50 ≈ 1 pM), improved activity against genotype 3a (GT 3a) and good metabolic stability. We studied the impact of changing the cap conformation relative to the diphenylethyne core and/or compound symmetry on both potency and metabolic stability. The analogs obtained exhibited improved potency against HCV genotypes 1a, 1b, 3a and 4a compared to the clinically approved candidate daclatasvir with EC50 values in the low picomolar range and SI50s > 7 orders of magnitude. Compound 15, a symmetrically m-, m’-substituted diphenyl ethyne analog, was 150-fold more potent than daclatasvir against GT 3a, while compound 33, an asymmetrically m-, p-substituted diphenyl ethyne analog, was 35-fold more potent than daclatasvir against GT 3a. In addition, compound 15 exhibited a higher resistance barrier than daclatasvir against genotype 1b.
- Abadi, Ashraf H.,Abdallah, Mennatallah,Abdel-Halim, Mohammad,Bartenschlager, Ralf,Frakolaki, Efseveia,Hamed, Mostafa M.,Hirsch, Anna K. H.,Katsamakas, Sotirios,Vassilaki, Niki,Zoidis, Grigoris
-
-
- Design and synthesis of novel symmetric fluorene-2,7-diamine derivatives as potent hepatitis C virus inhibitors
-
Hepatitis C virus (HCV) is an international challenge. Since the discovery of NS5A direct-acting antivirals, researchers turned their attention to pursue novel NS5A inhibitors with optimized design and structure. Herein we explore highly potent hepatitis C virus (HCV) NS5A inhibitors; the novel analogs share a common symmetrical prolinamide 2,7-diaminofluorene scaffold. Modification of the 2,7-diaminofluorene backbone included the use of (S)-prolinamide or its isostere (S,R)-piperidine-3-caboxamide, both bearing different amino acid residues with terminal carbamate groups. Compound 26 exhibited potent inhibitory activity against HCV genotype (GT) 1b (effective concentration (EC50) = 36 pM and a selectivity index of >2.78 × 106). Compound 26 showed high selectivity on GT 1b versus GT 4a. Interestingly, it showed a significant antiviral effect against GT 3a (EC50 = 1.2 nM). The structure-activity relationship (SAR) analysis revealed that picomolar inhibitory activity was attained with the use of S-prolinamide capped with R- isoleucine or R-phenylglycine residues bearing a terminal alkyl carbamate group.
- Mousa, Mai H. A.,Ahmed, Nermin S.,Schwedtmann, Kai,Frakolaki, Efseveia,Vassilaki, Niki,Zoidis, Grigoris,Weigand, Jan J.,Abadi, Ashraf H.
-
-
- Synthesis, characterization and docking studies of anti-HCV molecules
-
The present study reports the synthesis and characterization of novel molecules inhibiting the spread of hepatitis C. The molecules were designed as to block the NS3/4A protease enzyme on HCV RNA. The molecules were synthesized using usual peptide synthesis techniques. Compounds with purity more than 95% were characterized and docking studies were also performed. All the compounds were characterized using physico-chemical techniques such as determination of melting point by DSC and NMR, mass, IR spectral studies. The docking studies were also conducted to assess the activity of molecules for inhibition of hepatitis C virus.
- Kumar, Satish,Santra,Dwivedi,Aryan
-
p. 1221 - 1229
(2020/06/09)
-
- Enantioselective inclusion of pyrene-1-sulfonate salts of α-amino acids with crystals of α-cyclodextrin
-
Enantioselective inclusion of α-amino acids with crystals of α-cyclodextrin (α-CD) has been achieved by converting the amino acids into sulfonate salts with pyrene-1-sulfonic acid (PyS). For example, crystals of α-CD selectively include L-leucine/PyS (1:1) salt in a host/guest ratio of ～1 with 92%ee from a solution of the racemic salt in ethanol/N-methylformamide (91:9) at 40 °C. Under conditions optimized for individual amino acids, the PyS salts of valine, phenylalanine, and methionine are also included with good enantioselectivities (up to 86%ee). Mechanistic studies for the inclusion of leucine/PyS salt reveals that the enantioselectivity originates from the difference in stability between the inclusion complexes of D- and L-leucine/PyS salts with α-CD in crystals.
- Hattori, Tetsutaro,Kitamoto, Yuichi,Maeda, Tetsuya,Miyoshi, Ikuko,Morohashi, Naoya
-
supporting information
(2020/04/01)
-
- Chiral tetraaryl-and tetraalkynylborates as chiral solvating agents for tetraalkylammonium salts
-
The application of tetracarbon-substituted chiral borate sodium salts (NaBR*4) as NMR chiral solvating agents for various tetraalkylammonium salts (R4NX) has been successfully demonstrated. Ion exchange between R4NX and NaBR*4 proceeded in excellent yields and provided the corresponding dia-stereomeric salts (R4NBR*4). The ee values of the R4NX salts were determined by1H NMR analysis of R4NBR*4. Two types of chiral borates, tetraaryl-and tetraalkynylborates with optically active 1,1′-binaphthyl components were used. At the beginning of this research, we investigated the efficacy of a known chiral tetraar-ylborate developed by Pommerening et al. for R4NX. To expand the possibility of further structural design of the chiral borate, we designed chiral tetraalkynylborates as a new structure. Their synthesis and application are also described.
- Tayama, Eiji,Sugawara, Takeshi
-
p. 803 - 811
(2019/01/18)
-
- Preparation technology of (S)-3-carbobenzoxy-4-isopropyl-2,5-oxazolidinedione
-
The invention provides a preparation technology of (S)-3-carbobenzoxy-4-isopropyl-2,5-oxazolidinedione. The (S)-3-carbobenzoxy-4-isopropyl-2,5-oxazolidinedione can serve as a valganciclovir hydrochloride intermediate. The technology includes the following operations that an L-valine starting material reacts with benzyl chloroformate to generate N-carbobenzoxy-L-valine; the N-carbobenzoxy-L-valinereacts with N,N-carbonyl diimidazole (CDI) to generate the (S)-3-carbobenzoxy-4-isopropyl-2,5-oxazolidinedione. The preparation technology is simple in method, purification is easy, the process is stable, the quality is controllable, the product yield is greatly improved, environmental pollution is not caused, and the technology is suitable for industrial mass production.
- -
-
Paragraph 0049; 0050
(2019/10/01)
-
- Method for preparing N-benzyloxycarbonyl-L-valine
-
The invention relates to the technical field of synthesis of chemical organic substances, and in particular relates to a method for preparing N-benzyloxycarbonyl-L-valine. The method comprises the following steps: A, adding valine into water, adding benzyl chloroformate and a saturated potassium carbonate solution dropwise, controlling a pH value at 1.0-3.0 at temperature of -5 DEG C to 5 DEG C, and performing a reaction for 3-8 h to obtain an aqueous solution containing the N-benzyloxycarbonyl-L-valine; and B, performing extraction on the aqueous solution obtained in the step A by using an extraction solvent, performing washing by using a saturated saline solution, performing drying by using anhydrous sodium sulfate, performing concentration to remove the solvent, performing dissolving byusing ethyl acetate, and finally performing crystallization by using a crystallizing solvent to obtain the product. The method disclosed by the invention is performed under acidic conditions, and thepH is controlled by using the saturated potassium carbonate solution, so that the reaction is more stable; and the product has a yield of 99% or more and purity of 99.5%, and can be directly used ina next reaction of any other products.
- -
-
Paragraph 0012; 0014; 0016; 0017; 0018; 0020; 0022
(2019/01/06)
-
- Discovery of Peptidomimetic Antibody-Drug Conjugate Linkers with Enhanced Protease Specificity
-
Antibody-drug conjugates (ADCs) have become an important therapeutic modality for oncology, with three approved by the FDA and over 60 others in clinical trials. Despite the progress, improvements in ADC therapeutic index are desired. Peptide-based ADC linkers that are cleaved by lysosomal proteases have shown sufficient stability in serum and effective payload-release in targeted cells. If the linker can be preferentially hydrolyzed by tumor-specific proteases, safety margin may improve. However, the use of peptide-based linkers limits our ability to modulate protease specificity. Here we report the structure-guided discovery of novel, nonpeptidic ADC linkers. We show that a cyclobutane-1,1-dicarboxamide-containing linker is hydrolyzed predominantly by cathepsin B while the valine-citrulline dipeptide linker is not. ADCs bearing the nonpeptidic linker are as efficacious and stable in vivo as those with the dipeptide linker. Our results strongly support the application of the peptidomimetic linker and present new opportunities for improving the selectivity of ADCs.
- Wei, Binqing,Gunzner-Toste, Janet,Yao, Hui,Wang, Tao,Wang, Jing,Xu, Zijin,Chen, Jinhua,Wai, John,Nonomiya, Jim,Tsai, Siao Ping,Chuh, Josefa,Kozak, Katherine R.,Liu, Yichin,Yu, Shang-Fan,Lau, Jeff,Li, Guangmin,Phillips, Gail D.,Leipold, Doug,Kamath, Amrita,Su, Dian,Xu, Keyang,Eigenbrot, Charles,Steinbacher, Stefan,Ohri, Rachana,Raab, Helga,Staben, Leanna R.,Zhao, Guiling,Flygare, John A.,Pillow, Thomas H.,Verma, Vishal,Masterson, Luke A.,Howard, Philip W.,Safina, Brian
-
supporting information
p. 989 - 1000
(2018/01/01)
-
- Expanding the chemical space of anti-HCV NS5A inhibitors by stereochemical exchange and peptidomimetic approaches
-
Here we report a series of potent anti-HCV agents bearing a symmetrical benzidine l-prolinamide backbone with different capping groups including alkyl/aryl carbamates of natural and unnatural valine and leucine amino acids. All compounds were investigated for their inhibitory activity in an HCV replicon assay on genotype 1b. The novel compounds share some chemical and clinical attributes of commercially available NS5A inhibitors. Compounds 5 and 6 with unnatural capping residue and ethyl and isobutyl carbamates showed EC50 values in the picomolar range with a low toxicity profile and selectivity indices of several orders of magnitude. These findings enlarge the chemical space from which NS5A inhibitors may be discovered by adopting unnatural amino acids, amino acids other than valine and carbamates other than methyl as the capping groups.
- Ramsis, Triveena M.,Abdel Karim, Shereen E.,Vassilaki, Niki,Frakolaki, Efseveia,Kamal, Ahmed A. M.,Zoidis, Grigoris,Ahmed, Nermin S.,Abadi, Ashraf H.
-
-
- Synthesis and evaluation of chirally defined side chain variants of 7-chloro-4-aminoquinoline to overcome drug resistance in malaria chemotherapy
-
A novel 4-aminoquinoline derivative [(S)-7-chloro-N-(4-methyl-1-(4-methyl-piperazin-1-yl)pentan-2-yl)-quinolin-4-amine triphosphate] exhibiting curative activity against chloroquine-resistant malaria parasites has been identified for preclinical development as a blood schizonticidal agent. The lead molecule selected after detailed structure-activity relationship (SAR) studies has good solid-state properties and promising activity against in vitro and in vivo experimental malaria models. The in vitro absorption, distribution, metabolism, and excretion (ADME) parameters indicate a favorable drug-like profile.
- Dola, Vasantha Rao,Soni, Awakash,Agarwal, Pooja,Ahmad, Hafsa,Raju, Kanumuri Siva Rama,Rashid, Mamunur,Wahajuddin, Muhammad,Srivastava, Kumkum,Haq,Dwivedi,Puri,Katti
-
-
- Rational Design of Small Peptides for Optimal Inhibition of Cyclooxygenase-2: Development of a Highly Effective Anti-Inflammatory Agent
-
Among the small peptides 2-31, (H)Gly-Gly-Phe-Leu(OMe) (30) reduced prostaglandin production of COX-2 with an IC50 of 60 nM relative to 6000 nM for COX-1. The 5 mg kg-1 dose of compound 30 rescued albino mice by 80% from capsaicin-induced paw licking and recovered it by 60% from carrageenan-induced inflammation. The mode of action of compound 30 for targeting COX-2, iNOS, and VGSC was investigated by using substance P, l-arginine, and veratrine, respectively, as biomarkers. The interactions of 30 with COX-2 were supported by isothermal calorimetry experiments showing a Ka of 6.10 ± 1.10 × 104 M-1 and ΔG of -100.3 kJ mol-1 in comparison to a Ka 0.41 × 103 ± 0.09 M-1 and ΔG of -19.2 ± 0.06 kJ mol-1 for COX-1. Moreover, compound 30 did not show toxicity up to a 2000 mg kg-1 dose. Hence, we suggest peptide 30 as a highly potent and promising candidate for further development into an anti-inflammatory drug.
- Singh, Palwinder,Kaur, Sukhmeet,Kaur, Jagroop,Singh, Gurjit,Bhatti, Rajbir
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p. 3920 - 3934
(2016/05/24)
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- A kind of amino acid tanshinone phenolic derivative and its preparation method
-
The invention relates to amino acid tanshinone phenolic ester derivatives and a preparation method thereof. The derivatives are obtained by reducing tanshinone compounds and performing esterified modification on the reduced tanshinone compounds and an amino acid into prodrugs, wherein the tanshinone compounds are phenanthrenequinone compounds which exist in salvia miltiorrhiza and have an o-quinone structure; the esterified amino acid is alpha-amino acid. The amino acid tanshinone phenolic ester derivatives are compounds having a structure of a general formula (I) or medicinal salts thereof, wherein R1 and R2 represent H or acyl alpha-amino acid and a salt thereof, and R1 and R2 are not H at the same time. The amino acid tanshinone phenolic ester derivatives have the beneficial effects that firstly, the new tanshinone derivatives are provided and the new substances have potential treatment effect on some serious diseases such as tumors, and secondly, amino acid tanshinone phenolic ester derivatives have excellent water solubility and thus can be prepared into injections conveniently in addition to various oral preparations, and therefore, the amino acid tanshinone phenolic ester derivatives are capable of quickly taking effect in disease treatment. As important prodrugs, the amino acid tanshinone phenolic ester derivatives have important application value.
- -
-
Paragraph 0065
(2016/10/09)
-
- PEPTIDOMIMETIC COMPOUNDS AND ANTIBODY-DRUG CONJUGATES THEREOF
-
This invention relates to peptidomimetic linkers and anti-body drug conjugates thereof, to pharmaceutical compositions containing them, and to their use in therapy for the prevention or treatment of cancer.
- -
-
Page/Page column 194
(2015/07/07)
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- Synthesis and applications in Henry reactions of novel chiral thiazoline tridentate ligands
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Several novel chiral tridentate ligands containing thiazoline were efficiently synthesized from commercially available l=cysteine in high yield. These ligands were subsequently applied to the asymmetric Henry reaction of nitromethane and various aldehydes. It was found that the structures of the thiazoline ligands had a significant influence on the enantioselectivity. It was shown that the optimal catalyst for this reaction was a ligand complexed with CuCl, which was formed from chiral thiazoline with chiral aminoalcohol. At -20°C, with 10 mol% of this ligand, a product with (S)-configuration was isolated in 93% yield and 98% enantiomeric excess.
- Shi, Ye,Li, Yang,Sun, Jingbo,Lai, Qi,Wei, Chiyu,Gong, Zhiyong,Gu, Qiang,Song, Zhiguang
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p. 661 - 667
(2015/09/28)
-
- Synthesis of enantiopure free and N-benzyloxycarbonyl-protected 3-substituted homotaurines from naturally occurring amino acids
-
Enantiopure N-benzyloxycarbonyl-protected and free 3-substituted homotaurines were synthesized from naturally occurring amino acids via N-benzyloxycarbonyl protection, Arndt-Eistert homologation, reduction, esterification with thioacetic acid, and oxidation with performic acid. The current method is a convenient, practical, and salt-free method for the synthesis of enantiopure 3-substituted homotaurine with moderate to good yields.
- Zheng, Yongpeng,Xu, Jiaxi
-
p. 5197 - 5206
(2014/12/10)
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- METHOD FOR PRODUCING CARBOXYLIC ACID AND ALCOHOL BY HYDROLYSIS OF ESTER
-
As shown by the following formula (1), after methyl laurate (2 mmol) and water (8 mL) are added to an ammonium pyrosulfate catalyst (5 mol%), a hydrolysis reaction of methyl laurate is carried out by heating for 24 hours at 60°C while stirring is performed, so that lauric acid can be obtained with a yield of 86%.
- -
-
Paragraph 0069; 0070
(2014/11/13)
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- Toward waste-free peptide synthesis using ionic reagents and ionic liquids as solvents
-
CBEIT 1, an ionic coupling reagent, gives access to amino acid carbamates, and allows waste-free peptide coupling. The only by-products are carbon dioxide and ethylimidazolium triflate that is an ionic liquid playing the role of the solvent.
- Galy, Nicolas,Mazières, Marie-Rose,Plaquevent, Jean-Christophe
-
supporting information
p. 2703 - 2705
(2013/06/27)
-
- Design, synthesis, and biological evaluation of novel dipeptide-type SARS-CoV 3CL protease inhibitors: Structure-activity relationship study
-
This work describes the design, synthesis, and evaluation of low-molecular weight peptidic SARS-CoV 3CL protease inhibitors. The inhibitors were designed based on the potent tripeptidic Z-Val-Leu-Ala(-pyrrolidone-3-yl)-2-benzothiazole (8; Ki = 4.1 nM), in which the P3 valine unit was substituted with a variety of distinct moieties. The resulting series of dipeptide-type inhibitors displayed moderate to good inhibitory activities against 3CLpro. In particular, compounds 26m and 26n exhibited good inhibitory activities with Ki values of 0.39 and 0.33 μM, respectively. These low-molecular weight compounds are attractive leads for the further development of potent peptidomimetic inhibitors with pharmaceutical profiles. Docking studies were performed to model the binding interaction of the compound 26m with the SARS-CoV 3CL protease. The preliminary SAR study of the peptidomimetic compounds with potent inhibitory activities revealed several structural features that boosted the inhibitory activity: (i) a benzothiazole warhead at the S1′ position, (ii) a γ-lactam unit at the S1-position, (iii) an appropriately hydrophobic leucine moiety at the S2-position, and (iv) a hydrogen bond between the N-arylglycine unit and a backbone hydrogen bond donor at the S3-position.
- Thanigaimalai, Pillaiyar,Konno, Sho,Yamamoto, Takehito,Koiwai, Yuji,Taguchi, Akihiro,Takayama, Kentaro,Yakushiji, Fumika,Akaji, Kenichi,Kiso, Yoshiaki,Kawasaki, Yuko,Chen, Shen-En,Naser-Tavakolian, Aurash,Sch?n, Arne,Freire, Ernesto,Hayashi, Yoshio
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p. 436 - 447
(2013/10/01)
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- Original β,γ-diamino acid as an inducer of a γ-turn mimic in short peptides
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Original αγα tripeptides containing one β,γ-diamino acid have been synthesized and their conformation determined by extensive NMR and molecular dynamic studies. These studies revealed the presence of a C9 hydrogen bonded turn around the β,γ-diamino acid which was stabilized by bulky side chains of the preceding residue. This turn can be considered as a mimic of the well-known γ-turn. The Royal Society of Chemistry 2012.
- Thétiot-Laurent, Sophie,Bouillère, Francelin,Baltaze, Jean-Pierre,Brisset, Fran?ois,Feytens, Debby,Kouklovsky, Cyrille,Miclet, Emeric,Alezra, Valérie
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supporting information
p. 9660 - 9663
(2013/01/16)
-
- Photorelease of amino acids from novel thioxobenzo[f]benzopyran ester conjugates
-
Aiming at the enhancement of the performance of (9-methoxy-3-oxo-3H- benzo[f]benzopyran-1-yl) methyl ester as photocleavable protecting group for the carboxylic acid function at long-wavelengths, 9-methoxy-3-thioxo-3H-benzo[f] benzopyran-l-valine and l-phenylalanine model conjugates were prepared through a thionation reaction of the corresponding oxo-benzobenzopyrans. These thioxobenzobenzopyran derivatives were subjected to photocleavage reactions in the same conditions as the parent oxo-benzobenzopyrans at different wavelengths of irradiation, and photocleavage data were obtained. It was found that the exchange of the carbonyl by a thiocarbonyl group enhanced the performance of the heterocyclic protecting group at 419 nm by improving the photolysis rates, making it an appropriate group for practical applications at long wavelengths.
- Piloto, Ana M.,Soares, Ana M. S.,Costa, Susana P. G.,Goncalves, M. Sameiro T.
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experimental part
p. 2275 - 2282
(2012/08/29)
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- A mild method for the cleavage of the 4-picolyloxy group with magnesium under neutral conditions
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A mild and efficient method for the selective hydrolysis of 4-picolyl esters with magnesium in methanol or water in the presence of other esters and sensitive protecting groups is described. 4-Picolyl aryl ethers and thioethers are also smoothly deprotected to give the corresponding phenols and thiophenols. Georg Thieme Verlag Stuttgart. New York.
- Zhu, Jianwei,Miao, Wenjun,Bao, Lingling,Ji, Tao,Tang, Guo,Xu, Pengxiang,Zhao, Yufen
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supporting information; experimental part
p. 142 - 144
(2012/02/04)
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- N,N-diarylammonium pyrosulfate as a highly effective reverse micelle-type catalyst for hydrolysis of esters
-
Reverse micelle-type N,N-diarylammonium pyrosulfate (3-5 mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for α-heterosubstituted carboxylic acids.
- Koshikari, Yoshiki,Sakakura, Akira,Ishihara, Kazuaki
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supporting information; scheme or table
p. 3194 - 3197
(2012/07/31)
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- An improved large scale procedure for the preparation of N-Cbz amino acids
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A simple and scalable method for the preparation of N-Cbz protected amino acids is presented which uses a mixture of aqueous sodium carbonate and sodium bicarbonate to maintain the appropriate pH during the addition of benzyl chloroformate. The method has been extended to other N-protections and is amenable to large scale preparation of an intermediate toward Zofenopril, an ACE inhibitor.
- Pehere, Ashok D.,Abell, Andrew D.
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experimental part
p. 1493 - 1494
(2011/05/16)
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- Long-wavelength photolysis of amino acid 6-(methoxy-2-oxo-2H-naphtho[1,2-b] pyran-4-yl)methyl esters
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(6-Methoxy-2-oxo-2H-naphtho[1,2-b]pyran-4-yl)methyl esters of valine or phenylalanine as model bifunctional molecules were synthesised to assess its applicability as a photocleavable protecting group for solution phase organic synthesis and in caging applications at longer wavelengths. The behaviour of the corresponding derivatives towards photolysis was evaluated by irradiation at 350 and 419 nm in a mixture of HEPES buffer and acetonitrile or methanol in a photochemical reactor, followed by HPLC/UV monitoring. Time-resolved fluorescence measurements were used to elucidate the dynamics. Photocleavage studies of new valine orphenylalanine 2H-naphtho[1,2-b]pyran-4-yl)methyl esters revealed that the amino acid-heterocycle ester bond was efficiently photolysed, especially at 419 nm for all compounds in practical irradiation times. Copyright
- Piloto, Ana M.,Soares, Ana M. S.,Hungerford, Graham,Costa, Susana P. G.,Goncalves, M. Sameiro T.
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experimental part
p. 5447 - 5451
(2011/12/02)
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- Ligand-accelerated C-H activation reactions: Evidence for a switch of mechanism
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Initial rate studies have revealed dramatic acceleration in aerobic Pd(II)-catalyzed C-H olefination reactions of phenylacetic acids when mono-N-protected amino acids are used as ligands. In light of these findings, systematic ligand tuning was undertaken, which has resulted in drastic improvements in substrate scope, reaction rate, and catalyst turnover. We present evidence from intermolecular competition studies and kinetic isotope effect experiments that implies that the observed rate increases are a result of acceleration in the C-H cleavage step. Furthermore, these studies suggest that the origin of this phenomenon is a change in the mechanism of C-H cleavage from electrophilic palladation to proton abstraction.
- Engle, Keary M.,Wang, Dong-Hui,Yu, Jin-Quan
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supporting information; experimental part
p. 14137 - 14151
(2010/12/19)
-
- PROCESS FOR PREPARING ENANTIOMERICALLY ENRICHED AMINO-ALCOHOLS
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A process for preparing an enantiomerically enriched amino alcohol or derivatives thereof having the structure: wherein C* is a chiral carbon atom and R1 and R2 are independently selected from hydrogen, alkyl, alkoxy, aryl and a peptide chain, wherein said process includes the steps of: (a) providing an amino acid having the structure of Formula I: (b) protecting the amino group of the Formula I amino acid with a carbobenzoxy(Cbz) N-protecting group by reacting the amino acid with benzyl chloroformate in the presence of a base; (c) forming a carboxylic acid alkyl ester of the Cbz N-protected Formula I amino acid by reacting the amino acid with a C1-12 alcohol; and (d) reducing the Cbz N-protected amino acid ester with a borohydride reducing agent in an organic solvent or mixture of organic solvents to form a Cbz N-protected amino-alcohol
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Page/Page column 3
(2010/07/08)
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- Addition of allylzinc to a-amino acid-derived imines: Synthesis of diamino alcohols by Hydroboration
-
Imines obtained by condensation of Z-pro- tected or Boc-protected α-amino aldehydes with α-amino tert-butyl esters or with O-silyl-protected amino alcohols were reacted with preformed allyl zinc yielding homoal- lylamines with yields around 50% and selectivities ranging from 50:50 to 90:10. Hydroboration of the terminal double bond furnished diamino alcohols with yields up to 97%. The configuration of the substrates was determined by X-ray-crystallographic analysis of a hydroboration product and comparison of physical data. Springer-Verlag 2010.
- Virlouvet, Mickael,Goesmann, Helmut,Feldmann, Claus,Podlech, Joachim
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scheme or table
p. 177 - 198
(2010/08/05)
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- Stereoselective synthesis of chiral β-amino trifluoromethyl alcohol: Development of a manufacturing process for a key intermediate in the production of a novel elastase inhibitor, AE-3763
-
We have successfully synthesized chiral β-amino trifluoromethyl alcohol (2S,3S)-7a, which is a key intermediate in the production of AE-3763, by stereoselective reduction of N-Cbz-protected 5-hydroxy-5-(trifluoromethyl)- 1,3-oxazolidine 4 prepared from L-valine in 3 steps followed by alkaline hydrolysis. This new method can be applied to the industrial-scale synthesis of AE-3763.
- Inoue, Yasunao,Omodani, Tomoki,Shiratake, Ryotaro,Sato, Fuminori
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experimental part
p. 1855 - 1860
(2010/11/18)
-
- AmIno Acid Homologation by the Blaise Reaction: A new entry into nitrogen heterocycles
-
(Chemical Equation Presented) A general strategy for the amino acid homologation via Blaise reaction and subsequent reduction is presented. This strategy involves the preparation of protected α-amino nitriles from the corresponding amino acids, followed by the zinc-mediated condensation of tert-butyl bromoacetate, to give the imidazolidones after iminozincate cyclization. Reduction gave the saturated imidazolidinones with cis or trans stereochemistry, depending on the reduction conditions. This strategy was applied to nonfunctionalized amino acids and to functionalized amino acids such as serine and aspartic acid. Additionally, acidic hydrolysis of cis or trans imidazolidinones to the corresponding chiral 4-aminopyrrolidones is described.
- Cam, Thuy Hoang,Bouillere, Francelin,Johannesen, Sine,Zulauf, Anais,Panel, Cecilia,Pouilhes, Annie,Gori, Didier,Alezra, Valerie,Kouklovsky, Cyrille
-
scheme or table
p. 4177 - 4187
(2009/09/08)
-
- A Stereoselective entry into functionalized 1,2-diamines by zinc-mediated homologation of α-aminoacids
-
A general, stereoselective synthsis of 4,5-disubstituted imidazolidines-2-ones from α-aminoacids has been developed: the key steps are a Biaise reaction of bromoacetate on α-aminonitriles and further reduction. Although reduction with sodium cyanoborohydride afforded a mixture of cis and trans isomers 6a-e with moderate to good stereoselectivity, reduction with sodium in liquid ammonia gave the trans isomers 8a-e with complete stereoselectivity. Acidic hydrolysis of the urea gave 4-amino-pyrrolidinones, which can be precursors to β,γ-diaminoacids or 3-aminopyrrolidines.
- Hoang, Cam Thuy,Alezra, Valerie,Guillot, Regis,Kouklovsky, Cyrille
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p. 2521 - 2524
(2008/02/05)
-
- Microwave-assisted carbamoylation of amines
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The influence of microwave irradiation on the reaction of various amines with benzyl chloroformate and di-tert-butyl dicarbonate was investigated. Microwave irradiation was successfully applied to the carbamoylation of several nonfunctionalized and functionalized amines, including amino acids and nucleobases, leading to satisfactory to high product conversion within very short reaction times. Copyright Taylor & Francis Group, LLC.
- Azzena, Ugo,Dettori, Giovanna,Pisano, Luisa,Pittalis, Mario
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p. 3623 - 3634
(2008/03/13)
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- Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide
-
A Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide is described. Asymmetric allylic substitution using acyclic β-keto esters with a nitrogen functional group at the α-carbon as prochiral nucleophiles proceeded in the presence of 5 mol % of Pd catalyst, 10 mol % of chiral diaminophosphine oxide 1j, BSA, and appropriate additives, affording the corresponding quaternary α-amino acid derivatives in excellent yield and in up to 92% ee.
- Nemoto, Tetsuhiro,Harada, Teisuke,Matsumoto, Takayoshi,Hamada, Yasumasa
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p. 6304 - 6307
(2008/02/10)
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- Synthesis of chiral tropopodands having l-amino acid moieties and ability of their metal complexes as an asymmetric catalyst
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Optical active tropopodans (10 and 11) having neutral l-amino acids and l-histidine moieties were synthesized. Within their metal complexes, Pd complexes of histidine-tropopodands (11b and 11c) bearing bulky amide moieties showed good ability as an asymmetric catalyst in conjugate addition.
- Sato, Ohki,Koshiba, Yusuke,Sagara, Satoshi,Okada, Katsuyoshi
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p. 529 - 533
(2007/10/03)
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- Diastereoselective cationic tandem cyclizations to N-heterocyclic scaffolds: Total synthesis of (-)-dysibetaine PP
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Herein, we report a short and diastereoselective synthesis of the natural product (-)-dysibetaine PP. The key step in the synthetic sequence is a novel highly diastereoselective tandem-cyclization reaction of an enantiomerically pure dipeptide. This cyclization methodology is applied in the synthesis of a broader range of N-heterocyclic scaffolds.
- IJzendoorn, Denis R.,Botman, Peter N. M.,Blaauw, Richard H.
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p. 239 - 242
(2007/10/03)
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- Asymmetric hydrogenation of N-sulfonylated-α-dehydroamino acids: Toward the synthesis of an anthrax lethal factor inhibitor
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(Chemical Equation Presented) A novel and highly enantioselective Ru-catalyzed hydrogenation of N-sulfonylated-α-dehydroamino acids has been discovered and demonstrated in the synthesis of an anthrax lethal factor inhibitor (LFI). Herein, this methodology is used to prepare N-sulfonylated amino acids in up to 98% ee. This unprecedented hydrogenation uses a chiral Ru catalyst rather than Rh as typical for acylated dehydroamino acids and esters, and this work reports the first asymmetric hydrogenation of a tetrasubstituted dehydroamino acid derivative using a Ru catalyst.
- Shultz, C. Scott,Dreher, Spencer D.,Ikemoto, Norihiro,Williams, J. Michael,Grabowski, Edward J. J.,Krska, Shane W.,Sun, Yongkui,Dormer, Peter G.,DiMichele, Lisa
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p. 3405 - 3408
(2007/10/03)
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- Optically active tropocoronands having amino acid residues in linker chains: Syntheses, metal coordination properties, and their abilities as an asymmetric catalyst
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Optically active tropocoronands (7) having l-amino acid moieties were synthesized by stepwise and one-pot reactions of tropolone derivatives with amino acid linker chains. The coordination styles of their Ni(II) and Pd(II) complexes and the abilities as an asymmetric catalyst were investigated.
- Sato, Ohki,Tanbo, Akira
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p. 357 - 366
(2007/10/03)
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- Employing the structural diversity of nature: Development of modular dipeptide-analogue ligands for ruthenium-catalyzed enantioselective transfer hydrogenation of ketones
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A library of novel dipeptideanalogue ligands based on the combination of tert-butoxycarbonyl(N-Boc)-protected a-amino acids and chiral vicinal amino alcohols were prepared. These highly modular ligands were combined with [{RuCl2(p-cymene)}2 and the resulting metal complexes were screened as catalysts for the enantioselective reduction of acetophenone under transfer hydrogenation conditions using 2-propanol as the hydrogen donor. Excellent enantioselectivity of 1-phenylethanol (up to 98% ee) was achieved with several of the novel catalysts. Although most of the ligands contained two stereocenters, it was demonstrated that the absolute configuration of the product alcohol was determined by the configuration of the amino acid part of the ligand. Employing ligands based on L-amino acids generated S-configured products, and catalysts based on Damino acids favored the formation of the R-configured alcohol. The combination N-Boc-L-alanine and (R)-phenylglycinol (Boc-L-Ab) or its enantiomer (N-Boc-D-alanine and (S)-phenylglycinol, Boc-D-Aa) proved to be the best ligands for the reduction process. Transfer hydrogenation of a number of aryl alkyl ketones were evaluated and excellent enantioselectivity, up to 96 % ee, was obtained.
- Pastor, Isidro M.,Vaestilae, Patrik,Adolfsson, Hans
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p. 4031 - 4045
(2007/10/03)
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- A simple, mild and efficient procedure for selective cleavage of prenyl esters using silica-supported sodium hydrogen sulphate as a heterogenous catalyst
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Prenyl esters were selectively and efficiently cleaved under slightly acidic reaction conditions using silica-supported sodium hydrogen sulfate as a heterogenous catalyst at room temperature to regenerate the parent carboxylic acids in very high yields.
- Ramesh,Mahender,Ravindranath,Das, Biswanath
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p. 1465 - 1467
(2007/10/03)
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- A simple and efficient protocol for the deprenylation of ethers and esters catalysed by zirconium(IV) chloride-sodium iodide
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An efficient protocol for the deprotection of prenyl ethers and esters is developed using 20 mol% ZrCl4-NaI (1:1) in CH3CN as a reagent system. A variety of substrates as well as functional groups well tolerate the present reaction conditions.
- Sharma, Gangavaram V. M.,Reddy, Ch. Govardhan,Krishna, Palakodety Radha
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p. 1728 - 1730
(2007/10/03)
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- Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonyl-amino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
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A series of eleven α-aminoacyl stabilised phosphorus ylides 9-19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3P = CHCO2Et using a carbodiimide peptide coupling reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21-29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21-23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37-40 in 70 ->95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.
- Aitken, R. Alan,Karodia, Nazira,Massil, Tracy,Young, Robert J.
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p. 533 - 541
(2007/10/03)
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- Tripeptidylpeptidase inhibitors
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A compound of formula wherein the substituents are defined as in the specification and salts or hydrates thereof is disclosed as well as a method of treating disorders associated with the inactivation or excessive degradation of cholecystokinin.
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- IBX-mediated oxidation of primary alcohols and aldehydes to form carboxylic acids
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Under mild conditions and without the use of toxic metals, the oxidation of primary alcohols and aldehydes to the corresponding carboxylic acids with 1-hydroxy-1,2-benziodoxole-3(1H)-one-1-oxide (IBX) proceeds in the presence of 1-hydroxypyridine or N-hydroxysuccinimide (see scheme). The reaction tolerates a wide variety of functional groups.
- Mazitschek, Ralph,Muelbaier, Marcel,Giannis, Athanassios
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p. 4059 - 4061
(2007/10/03)
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- A facile and selective cleavage of prenyl esters catalyzed by CeCl3·7 H2O-NaI
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A highly selective cleavage of prenyl esters has been achieved in high yields using CeCl3·7 H2O-NaI in refluxing acetonitrile under neutral conditions. This method is mild and compatible with a wide variety of functional groups such
- Yadav,Subba Reddy,Venkateshwara Rao,Chand,Prasad
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p. 137 - 139
(2007/10/03)
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- Highly selective deprotection of tert-butyl esters using ytterbium triflate as a catalyst under mild conditions
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Ytterbium triflate catalyses the deprotection of tert-butyl esters selectively in the presence of other esters under mild conditions in almost quantitative yields. The reactions are carried out in nitromethane (45°-50°C) using 5 mole percent of the catalyst.
- Sridhar, P. Ramu,Sinha, Surajit,Chandrasekaran
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p. 157 - 160
(2007/10/03)
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- A novel concept in combinatorial chemistry in solution with the advantages of solid-phase synthesis: Formation of N-betaines by multicomponent domino reactions
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Advantages of solid-phase and liquid-phase synthesis are combined in a new concept of combinatorial chemistry: a domino sequence comprising Knoevenagel and hetero-Diels-Alder reactions, with subsequent hydrogenation starting from protected aminoaldehydes, 1.3-dicarbonyl compounds, and enol ethers leads to N-heterocycles of high diversity with a betaine structure, which are isolated in highly pure form by precipitation with diethyl ether (see scheme), Cbz = benzylocycarbonyl, Bn = benzyl.
- Tietze, Lutz F.
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p. 903 - 905
(2007/10/03)
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- 2(3H)-and 2(5H)-furanones. VIII. Preparation and α nucleophilicity of (S)-γ-isopropyl-α-methyl-β-tetramic acid
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An efficient preparation of (S)-γ-isopropyl-α-methyl-β-tetramic acid has been established, and the α nucleophilicity of the acid has been also examined.
- Toyooka, Naoki,Nishio, Morihiro,Shinoda, Hiroyuki,Momose, Takefumi
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p. 1427 - 1431
(2007/10/03)
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- New facile alkoxycarbonylating agent, alkyl pyrazole-1-carboxylates. The preparation and the utilities
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Alkyl pyrazole-1-carboxylates (2), which were readily prepared from alkyl chloroformate or carbazate in good yields, were provided as the new facile alkoxycarbonylating agents toward the Grignard reagents for the synthesis of one carbon higher carboxylic esters. Also amines were alkoxycarbonylated by 2 to produce the corresponding urethanes even in an aqueous medium. Benzyl 3,5-dimethylpyrazole-1-carboxylate (2d) could be utilized for the Cbz-protection of amino acids and esters in good yield without any racemization.
- Kashima, Choji,Tsuruoka, Shiro,Mizuhara, Saori
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p. 14679 - 14688
(2007/10/03)
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- Convenient protection of amines as carbamates using polymer-bound HOBT as catalyst
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A method for the facile protection of primary and secondary amines as carbamate (Cbz, Fmoc and t-Boc) derivatives using polymer bound 1-hydroxybenzotriazole (HOBT) is reported.
- Dendrinos, Kleanthis G.,Kalivretenos, Aristotle G.
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p. 1463 - 1464
(2007/10/03)
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- Remarkable effects of donor esters on the α-chymotrypsin-catalyzed couplings of inherently poor amino acid substrates
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The extremely low efficiency during the α-chymotrypsin-catalyzed coupling of an inherently poor amino acid substrate, e.g., alanine, using the methyl ester as an acyl donor was significantly improved using esters such as the 2,2,2-trifluoroethyl or carbamoylmethyl ester. The ameliorating effect of the latter ester was especially significant.
- Miyazawa, Toshifumi,Tanaka, Kayoko,Ensatsu, Eiichi,Yanagihara, Ryoji,Yamada, Takashi
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p. 997 - 1000
(2007/10/03)
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