- An in situ FT-IR study on photocatalytic reaction at semiconductor-aqueous solution interface - Mechanism of photocatalytic N-cyclization of (S)-lysine
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Photoinduced reaction occurring at an aqueous solution-semiconductor interface was analyzed in situ by reflection FT-IR spectroscopy. The photoinduced reflection spectral change, ΔR (= (R-R0)/R0), was recorded by using an IR cell consisting of a semiconductor (TiCO2 or CdS) thin film electrode, a thin layer of aqueous (S)-lysine solution, and a calcium fluoride window. Structure of adsorbed substrate and mechanism of photoinduced reaction were discussed.
- Ohtani, Bunsho,Yako, Takayuki,Samukawa, Yoriaki,Nishimoto, Sei-Ichi,Kanamura, Kiyoshi
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- Photocatalytic Synthesis of Pipecolic Acid from Lysine on TiO2: Effects of the Structure of Catalysts and Adsorbed Species on Chiral Selectivity
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A one-step photocatalytic synthesis of l-pipecolic acid (l-PCA) from l-lysine (l-Lys) has been investigated by in situ infrared (IR), circular dichroism, and 1H NMR spectroscopy. Chiral selectivity toward l-Lys was found to be governed by the structure of adsorbed l-Lys and the structure of TiO2. Both anatase and rutile were not able to catalyze the reaction in a solvent-free environment. In situ IR studies revealed that l-Lys adsorbed on these TiO2 in a dicationic form of which the positive -NH3+ functional groups are not able to interact with photogenerated holes. Interestingly, P-25 TiO2, which contains 80 wt % anatase and 20 wt % rutile, adsorbs l-Lys in a zwitterionic form, allowing its hydrogen in the α-amino group to be abstracted by the photogenerated hole, producing racemic PCA. The addition of H2O as a solvent allowed l-Lys to be adsorbed on P-25 in an anionic form, producing l-PCA as a major product. This study demonstrates that the reaction environment has a direct impact on the structure of adsorbed species that controls the selectivity of a chiral synthesis.
- Zhai, Yuxin,Chuang, Steven S. C.
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Read Online
- Recyclable Rh-PVP nanoparticles catalyzed hydrogenation of benzoic acid derivatives and quinolines under solvent-free conditions
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Various transition metal nanoparticles, prepared by microwave-assisted alcohol reduction method were examined for hydrogenation of benzoic acid to cyclohexanecarboxylic acid under solvent-free conditions. Rh metal was the most effective catalyst over other metal catalyst. The catalyst showed moderate to high yield for the hydrogenation of substituted benzoic acid and substituted quinolines. Rh-PVP was recycled four times with a minor loss in catalytic activity.
- Chaudhari, Chandan,Imatome, Hirotaka,Nishida, Yoshihide,Sato, Katsutoshi,Nagaoka, Katsutoshi
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- Encapsulation of Nonprecious Metal into Ordered Mesoporous N-Doped Carbon for Efficient Quinoline Transfer Hydrogenation with Formic Acid
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Ordered mesoporous N-doped carbon (OMNC) encapsulating Co nanoparticles (NPs) have been prepared under direct polymerization between [Co(NH2CH2CH2NH2)2]Cl2 and carbon tetrachloride through a hard template method. The catalysts (Co@OMNC) are pyrolyzed at various temperatures and characterized by elemental analysis, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In the quinoline transfer hydrogenation with formic acid (FA) as the hydrogen source under a base-free condition, the encapsulated Co NPs are physically isolated from the acidic reaction solution, which prevents them from poisoning or leaching. The rich mesopores and N dopants afford enhanced adsorption of quinoline. Co@OMNC-700 (pyrolyzed at 700 °C) gives the best activity (98.8% conversion) as well as >99% 1,2,3,4-tetrahydroquinoline (THQ) selectivity at 140 °C for 4 h, exhibiting significantly improved performance compared to using H2 as the hydrogenation source. Moreover, Co@OMNC-700 is stable for recycling and exhibits high efficiency in FA dehydrogenation. Co@OMNC-700 is also a high-performance catalyst in the transfer hydrogenation of various unsaturated hydrocarbons. On the contrary, without the protection of OMNC, the exposed Co NPs in a control catalyst, Co/OMNC-700, lead to obvious Co leaching and low efficiency for the transfer hydrogenation of quinoline with FA.
- Li, Guoqiang,Yang, Huanhuan,Zhang, Haifu,Qi, Zhiyuan,Chen, Minda,Hu, Wei,Tian, Lihong,Nie, Renfeng,Huang, Wenyu
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p. 8396 - 8405
(2018/08/17)
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- Focal adhesion kinase inhibitor and use
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The invention belongs to the field of medicines, relates to a focal adhesion kinase inhibitor and use, in particular relates to a novel focal adhesion kinase inhibitor compound, or stereoisomers, geometric isomers, tautomers, oxynitrides, hydrates, solvates, metabolites, pharmaceutically acceptable salts or prodrugs thereof, further relates to the use of the compound and pharmaceutical compositions as medicines, in particular the use of the compound and pharmaceutical compositions in manufacture of medicines for treatment or prevention of cancer, pulmonary hypertension, and pathological angiogenesis-related diseases.
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Paragraph 0404; 0406; 0408
(2019/01/08)
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- PROCESS FOR PRODUCING SOLID AMINO ACID
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The problem to be solved by the present invention is to ea lily and efficiently produce an amino acid having 2 to 7 carbon atoms as a high-purity solid without complicated operation, which is useful as a synthetic intermediate for medicines or agrochemicals. The present invention is characterized in comprising a step of precipitating solid amino acid with high purity. In the present invention, the by-produced salt composed of the sulfonic acid and the amine was removed to the mother liquor by reacting an amine with a sulfonic acid salt of amino acid in an aprotic polar solvent, or by reacting a sulfonic acid with an amine salt of amino acid in an aprotic polar solvent. The sulfonic acid salt of amino acid, for example, may be produced by reacting a N-(tert-butoxycarbonyl) amino acid with a sulfonic acid, or by reacting an amino acid tert-butyl ester with a sulfonic acid.
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Paragraph 0055
(2014/12/09)
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- Synthetic cascades are enabled by combining biocatalysts with artificial metalloenzymes
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Enzymatic catalysis and homogeneous catalysis offer complementary means to address synthetic challenges, both in chemistry and in biology. Despite its attractiveness, the implementation of concurrent cascade reactions that combine an organometallic catalyst with an enzyme has proven challenging because of the mutual inactivation of both catalysts. To address this, we show that incorporation of a d 6 -piano stool complex within a host protein affords an artificial transfer hydrogenase (ATHase) that is fully compatible with and complementary to natural enzymes, thus enabling efficient concurrent tandem catalysis. To illustrate the generality of the approach, the ATHase was combined with various NADH-, FAD- and haem-dependent enzymes, resulting in orthogonal redox cascades. Up to three enzymes were integrated in the cascade and combined with the ATHase with a view to achieving (i) a double stereoselective amine deracemization, (ii) a horseradish peroxidase-coupled readout of the transfer hydrogenase activity towards its genetic optimization, (iii) the formation of L-pipecolic acid from L-lysine and (iv) regeneration of NADH to promote a monooxygenase-catalysed oxyfunctionalization reaction.
- Koehler,Wilson,Duerrenberger,Ghislieri,Churakova,Quinto,Knoerr,Haeussinger,Hollmann,Turner,Ward
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- A concise and diastereoselective synthesis of piperidine and indolizidine alkaloids via aza-Prins cyclization
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The synthesis of 2-substituted and 2,4-disubstituted piperidine alkaloids such as (±)-coniine, (±)-hydroxypipecolic acid, (±)-pipecolic acid, (±)-coniceine, and (±)-4-hydroxy-2- hydroxy-methyl piperidine have been accomplished in a highly diastereo-selective manner by employing aza-Prins cyclization as a key step to construct the piperidine core of these alkaloids. Georg Thieme Verlag Stuttgart · New York.
- Reddy, Basi V. Subba,Chaya, Dudhmal N.,Yadav, Jhillu S.,Gree, Rene
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experimental part
p. 297 - 303
(2012/03/26)
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- Continuous flow hydrogenation of functionalized pyridines
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The heterogeneous hydrogenation of substituted pyridines has been accomplished by employing a continuous flow hydrogenation device that incorporates in situ hydrogen generation by electrolysis of H20 and pre-packed catalyst cartridges. In general, the hydrogenation reactions proceeded smoothly regardless of the supported precious metal catalyst (Pd/C, Pt/C, or Rh/C). By using 30-80 bar of hydrogen pressure at 60-80 °C full conversion was typically achieved in all cases at a flow rate of 0.5 mL min -1, providing the corresponding piperidines in high yields. For disubstituted pyr idines, variations in stereoselectivity were observed depending on both the metal catalyst and the temperature/ pressure of the hydrogenation reaction. For ethyl nicotinate the selectivity between partial and full hydrogenation could be tuned depending on the hydrogen pressure, solvent, and the choice of supported metal catalyst. Changing the hydrogen source from H20 to D2C) allowed the preparation of de-uteriated derivatives. Wiley-VCH Verlag GmbH & Co. KGaA.
- Irfan, Muhammed,Petricci, Elena,Glasnov, Toma N.,Taddei, Maurizio,Kappe, C. Oliver
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experimental part
p. 1327 - 1334
(2009/07/19)
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- CATALYTIC DEAMINATION FOR CARPROLACTAM PRODUCTION
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Catalytic processes for preparing caprolactam, pipecolinic acid, and their derivatives, from lysine or alpha-amino-epsilon-caprolactam starting materials, and products produced thereby. A process for preparing caprolactam or a derivative thereof, the process comprising contacting a reactant comprising lysine or alpha aminocaprolactam with a catalyst and a gas comprising hydrogen gas, in the presence of a solvent. The catalyst may be provided on a support material, such as a transition metal.
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Page/Page column 17, 19
(2008/12/08)
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- Simple and efficient microwave-assisted hydrogenation reactions at moderate temperature and pressure
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A generally applicable method for the introduction of gaseous hydrogen into a sealed reaction system to perform hydrogenation reactions under microwave irradiation has been developed. Several different types of substrates are easily reduced in short reaction times with moderate temperatures between 80 °C and 100 °C with 50 psi of hydrogen. The use of simultaneous cooling is also applied to the hydrogenation of more difficult substrates. Georg Thieme Verlag Stuttgart.
- Vanier, Grace S.
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p. 131 - 135
(2008/03/13)
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- Microwave-enhanced hydrogenations at medium pressure using a newly constructed reactor
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The newly constructed reactor for hydrogenations in microwave fields allows to work out the syntheses up to 25 bar. This is shown for the synthesis of intermediates of active agents. In order to demonstrate the superiority of the microwave-assisted hydrogenation, the reactions are compared with classical hydrogenations. The following reactions were carried out: dearomatization, debenzylation, azide hydrogenation and the hydrogenation of strychnine.
- Heller, Eberhard,Lautenschl?ger, Werner,Holzgrabe, Ulrike
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p. 1247 - 1249
(2007/10/03)
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- VITAMIN COMPRISING PYROLOQUINOLINE QUINONE AND USE THEREOF
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It is an object of the present invention to clarify the biochemical role of pyrroloquinoline quinone (PQQ) in living bodies by identifying an enzyme that uses PQQ as a coenzyme in mammals and then by clarifying the oxidation-reduction reaction, with which PQQ is associated as a coenzyme in living bodies. The present invention provides a method of using pyrroloquinoline quinone as a coenzyme for 2-aminoadipate 6-semialdehyde dehydrogenase.
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Page/Page column 20
(2008/06/13)
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- Kinetics and mechanisms of gas phase elimination of ethyl 1-piperidine carboxylate, ethyl pipecolinate, and (revisited) ethyl 1-methyl pipecolinate
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The kinetics of the gas-phase elimination of the title compounds has been determined in a static reaction system over the temperature range of 340-420°C and pressure range of 45-96 Torr. The reactions proved to be homogeneous, unimolecular, and obey a first-order rate law. The estimated rate coefficients are represented by the following Arrhenius expressions: Ethyl 1-piperidine carboxylate log k1 (S-1) = (12.61 ± 0.11) - (191.1 ± 1.4) kJ mol-1 (2.303 RT)-1, r = 0.9999 Ethyl pipecolinate log k1 (S-1) = (12.87 ± 0.16) - (204.3 ± 2.1) kJ mol-1 (2.303 RT)-1, r = 0.9998 Ethyl 1-methyl pipecolinate log k1 (S-1) = (13.34 ± 0.32) - (209.4 ± 4.0) kJmol-1 (2.303 RT) -1, r = 0.9992 The first step of decomposition of these esters is the formation of the corresponding carboxylic acids and ethylene. The acid intermediate undergoes a very fast decarboxylation process. The mechanism of this elimination reactions is suggested on the basis of the kinetic and thermodynamic parameters.
- Rosas, Felix,Monsalve, Angiebelk,Tosta, Maria,Herize, Armando,Dominguez, Rosa M.,Brusco, Doris,Chuchani, Gabriel
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p. 383 - 389
(2007/10/03)
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- Reaction of (di)amines in the presence of a lysine oxidase and of a reducing agent
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The present invention relates to a method for reacting amines of the general formula (I) with A- meaning to give compounds of the general formula (II) or (III) with B- meaning HO—CH2—R3— or R4— comprising the following steps: a) oxidation of at least one group of an amine of the general formula (I) to a carbonyl group in the presence of a lysine oxidase as catalyst; b) where appropriate reaction of the second NH2 group of an amine of the general formula (I) with with the carbonyl group resulting from a) to give an enamine or imine by cyclization; c) reduction of the carbonyl group(s) resulting from a), or of the enamine or imine resulting where appropriate from b), with a reducing agent respectively to hydroxymethyl groups or to a cyclic secondary amine of the general formula (II), where R1 is NR5 or a linear bivalent C2-C6 hydrocarbon radical which is optionally substituted by CO2H, CO2R6, OH, SH and/or N(R5)2 and/or contains nonadjacent O, S and/or N atoms, where R5 is H or linear C1-C6-alkyl and R6 is linear Cl-C6-alkyl or branched C3-C6-alkyl or C6-C10-aryl, and R2 is H, CO2H, CO2R6 or CN, where the method is carried out as a one-pot method, lysine oxidase and reducing agent are present together, and in the definition of A in the general formula (I) R3 is a bivalent C0-C1 or C5-C18 hydrocarbon radical which is optionally substituted by linear C1-C6-alkyl or branched C3-C6-alkyl, C6-C10-aryl, C4-C10-heteroaryl and/or CO2R6 and/or contains nonadjacent O, S and/or N atoms, and R4 is a linear C1-C20 hydrocarbon radical which is optionally substituted by functional groups such as CO2H and/or C02R6 and/or contains nonadjacent O, S and/or N atoms.
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- Compositions of matter having bioactive properties
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Particles of coordinated complex comprising a basic, hydrous polymer and a capacitance adding compound, as well as methods for their production, are described. These complexes exhibit a high degree of bioactivity making them suitable for a broad range of applications through their incorporation into conventional vehicles benefiting from antimicrobial and similar properties.
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- Azapeptides useful in the treatment of Hepatitis C
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The present invention relates to azapeptide compounds represented by the formula: pharmaceutical compositions containing such compounds, and the use thereof in the treatment of Hepatitis C viral infections.
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- Heterocyclic substituted aniline calcium channel blockers
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The present invention provides compounds that block calcium channels having the Formula I shown below. STR1The present invention also provides methods of using the compounds of Formula I to treat stroke, cerebral ischemia, head trauma, epilepsy, asthma, amyotrophic lateral sclerosis, or pain and to pharmaceutical compositions that contain the compounds of Formula I.
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- Composition of matter having bioactive properties
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Particles of coordinated complex comprising a basic, hydrous polymer and a capacitance adding compound, as well as methods for their production, are described. These complexes exhibit a high degree of bioactivity making them suitable for a broad range of applications through their incorporation into conventional vehicles benefiting from antimicrobial and similar properties.
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- Photocatalytic activity of transition-metal-loaded titanium(IV) oxide powders suspended in aqueous solutions: Correlation with electron-hole recombination kinetics
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Photocatalytic reactions by transition-metal (V, Cr, Fe, Co, Cu, Mo, or W) loaded TiO2 (M-TiO2) powders suspended in aqueous solutions of methanol, (S)-lysine (Lys), or acetic acid were investigated. The photoactivities of various samples were compared with the rate constant (kr) of recombination of photoexcited electrons and positive holes determined by femtosecond pump-probe diffuse reflection spectroscopy (PP-DRS). As a general trend, increased loading decreased the rate of formation of the main products (H2, pipecolinic acid (PCA), and CO2) under UV (> 300 nm) irradiation, and the effect became more intense on increasing the loading. In PP-DRS, these M-TiO2 gave similar decays of absorption at 620 nm arising from excitation by a 310 nm pulse (r) markedly increased with loading, even at a low level (0.3%) and further increased with an increase in loading up to 5%. The photocatalytic activity of platinized M-TiO2 for H2 and PCA production under deaerated conditions depended strongly on kr, but the relation between kr and the rate of CO2 production by unplatinized M-TiO2 under aerated conditions was ambiguous; other factor(s) might control the rate of the latter. These different kr dependences of photoactivity on the reaction kinetics governed by e--h+ recombination were attributed to the presence of O2 and Pt deposits. A simple kinetic model to explain the overall rate of these photocatalytic reactions is proposed, and the effect of recombination kinetics on photoactivity is discussed.
- Ikeda,Sugiyama,Pal,Marci,Palmisano,Noguchi,Uosaki,Ohtani
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p. 267 - 273
(2007/10/03)
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- Enantioselective homogeneous hydrogenation of monosubstituted pyridines and furans
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The first case of an enantioselective hydrogenation of monosubstituted pyridines and furans with homogeneous rhodium diphosphine catalysts with low but significant enantioselectivities and catalyst activities is reported. Best enantioselectivities (ees of 24-27%) were obtained for the hydrogenation of 2-and 3-pyridine carboxylic acid ethyl ester and 2-furan carboxylic acid with catalysts prepared in situ from [Rh(nbd)2]BF4 and the chiral ligands diop, binap, or ferrocenyl diphosphines of the josiphos type. Turnover numbers (ton) were in the order of 10-20, turnover frequencies (tof) usually 1-2 h-1. Diphosphines giving 6-or 7-ring chelates led to higher ees than 1,2-diphosphines; otherwise, no clear correlation between ligand properties and catalytic performance was found. In some experiments black precipitates were observed at the end of the reaction, indicating the decomposition of the homogeneous catalysts for certain ligand/metal/ substrate combinations.
- Studer, Martin,Wedemeyer-Exl, Christina,Spindler, Felix,Blaser, Hans-Ulrich
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p. 1335 - 1343
(2007/10/03)
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- Racemization of precursors to levobupivacaine and analogues thereof
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A process for the preparation of optically-enriched pipecolic acid as a salt with an optically-active acid, comprises asymmetric transformation of pipecolic acid, as a racemic mixture of a mixture enriched in the opposite enantiomer from that desired, with the optically-active acid in a solvent comprising an acid that causes racemisation, in the absence of aldehyde.
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- Synthesis and biological evaluation of substituted 4-(OBz)phenylalanine derivatives as novel N-type calcium channel blockers
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Selective N-type Voltage Activated Calcium Channel (VACC) blockers have shown utility in several models of stroke and pain. In the process of searching for small molecules as N-type calcium channel blockers, we have identified a series of N,N-dialkylpeptidylamines (e.g., PD 175069) with potent functional activity at N-type VACC. Further modification of the leucine moiety of PD 175069 with a cyclized ring structure provides a series of novel molecules. Syntheses and pharmacological evaluation of the series are presented.
- Hu, Lain-Yen,Ryder, Todd R.,Nikam, Sham S.,Millerman, Elizabeth,Szoke, Balazs G.,Rafferty, Michael F.
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p. 1121 - 1126
(2007/10/03)
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- Inhibitors of interleukin-1β converting enzyme
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The present invention relates to novel classes of compounds which are inhibitors of interleukin-1β converting enzyme. The ICE inhibitors of this invention are characterized by specific structural and physicochemical features. This invention also relates to pharmaceutical compositions comprising these compounds. The compounds and pharmaceutical compositions of this invention are particularly well suited for inhibiting ICE activity and consequently, may be advantageously used as agents against interleukin-1 mediated diseases, including inflammatory diseases, autoimmune diseases and neurodegenerative diseases. This invention also relates to methods for inhibiting ICE activity and methods for treating interleukin-1 mediated diseases using the compounds and compositions of this invention.
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- Polymerization- and solvent-triggered cooperativity between copper(II) ions in the catalysis of the hydrolysis of amino esters by pyridine-based ligands
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Polymeric (2) and oligomeric (4, 5) materials made of repeating units of 2,6-diaminomethylpyridine and 4,4′-diphenylmethane have been synthesized with the number of monomeric units (n) ranging from 2 to 29. In 1:1 DMSO/water solutions, these materials are fully soluble and strongly bind CuII ions. The complexes catalyze to different extents the hydrolysis of the p-nitrophenyl esters of α-, β-, and γ-amino acids. Only CuII complexes of polymeric 2 (n ≥ 10) are more effective catalysts than free CuII ions in the cleavage of β-amino esters. Such enhanced reactivity, which in the case of β-alanine p-nitrophenyl ester (β-AlaPNP) amounts to almost two orders of magnitude when the comparison is made with the CuII complex of monomeric ligand (N,N'-benzyl)-2,6-aminomethylpyridine (3), is observed in 1:1 (v/v) DMSO/H2O only when a certain degree of polymerization is reached (6 3CH2OH/H2O the kinetic benefits of the complexes of polymer 2 (n = 10) diminishes and vanishes in 9:1 (v/v) CH3CH2OH/H2O. Analysis of rate data suggests that two neighboring CuII ions bound to the polymeric ligands cooperate for the occurrence of the hydrolytic process: one of them coordinates the amino group of the substrate so that the carbonyl of the carboxylate faces the second metal ion which delivers a bound hydroxyl acting as the nucleophilic species. The selectivity toward β-amino ester is likely associated with a rather rigid conformation of these metallopolymers which places two metal centers at the appropriate distance one from the other. It is suggested that the onset of the metal ion cooperativity is connected to a conformational change of the metallopolymer from an extended to a globular structure, likely triggered by hydrophobic forces.
- Scrimin, Paolo,Tecilla, Paolo,Tonellato, Umberto
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p. 1143 - 1153
(2007/10/03)
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- Antiatherosclerotic and antithrombotic 1-benzopyran-4-ones and 2-amino-1,3-benzoxazine-4-ones
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This invention relates to compounds of Formula I STR1 which are useful in association with a pharmaceutical carrier as antiatherosclerotic agents. In addition, various compounds of Formula I are useful inhibitors of cell proliferation.
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- Role of platinum deposits on titanium(IV) oxide particles: Structural and kinetic analyses of photocatalytic reaction in aqueous alcohol and amino acid solutions
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Photocatalytic reaction at 298 K by platinum-loaded titanium(IV) oxide (TiO2-Pt) particles suspended in deaerated aqueous solutions of 2-propanol or (S)-lysine (Lys) was investigated. The TiO2 catalysts with various amounts of Pt loadings were prepared by impregnation from aqueous chloroplatinic acid solution onto a commercial TiO2 (Degussa P-25) followed by hydrogen reduction at 753 K. The physical properties of deposited Pt, e.g., particle size, surface area, and electronic state, were studied respectively by transmission electron microscopy, volumetric gas adsorption measurement, and X-ray photoelectron spectroscopy as well as infrared spectroscopy of adsorbed carbon monoxide. The increase in Pt amount mainly resulted in an increase of the number of Pt deposits, not of their size. The catalysts were suspended in the aqueous solutions and photoirradiated at a wavelength >300 nm under an argon (Ar) atmosphere. The overall rate of photocatalytic reactions for both 2-propanol and Lys, corresponding to the rate of consumption of these substrates, was negligible without Pt loading, increased drastically with the loading up to ca. 0.3%, and was almost constant or a little decreased by the further loadings. However, the rate of formation of pipecolinic acid (PCA) from Lys was improved gradually with a increase of Pt loading up to ca. 2 wt %. These dependences were discussed as a function of Pt surface area, which is employed as a measure that includes the properties of both number and size of Pt deposits. For the photocatalytic dehydrogenation of 2-propanol, the rate dependence could be interpreted semiquantitatively with the model that only the TiO2 particles loaded with at least one Pt deposit can photocatalyze, but the reaction rate is independent of the number of Pt deposits. Therefore, the overall rate is proportional to the number of Pt-loaded TiO2 particles. On the other hand, for the interpretation of the rate of PCA and H2 productions, the number of Pt deposits on each TiO2 particle had to be taken into account. The efficient production of PCA at higher Pt loadings was attributed to the reduction of a Schiff base intermediate produced via oxidation of Lys with positive holes and subsequent intramolecular condensation at the Pt deposit that is close to the site for the oxidation. Otherwise, photoexcited electrons are consumed for H2 production and the intermediate remains unreduced or undergoes further oxidation. It was suggested that the intermediate produced at the TiO2 surface sites within a distance of several nanometers from the Pt deposit undergoes efficient reduction to PCA. Thus, the importance of the distribution of Pt deposits for the preparation of highly active and selective TiO2-Pt photocatalyst has been clearly demonstrated.
- Ohtani, Bunsho,Iwai, Kunihiro,Nishimoto, Sei-Ichi,Sato, Shinri
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p. 3349 - 3359
(2007/10/03)
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- Synthesis of (2S*,4R*,5S*)-piperidinetricarboxylic acid, a non-proteinogenic amino acid isolated from clitocybe acromelalga
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(255*,4R*,5S*)-Piperidinetricarboxylic acid isolated from a poisonous mushroom Clitocybe acromelalga was synthesized along with its stereoisomers and their depolarizing activity was tested.
- Hashimoto, Kimiko,Higashibayashi, Shuhei,Shirahama, Haruhisa
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p. 581 - 588
(2007/10/03)
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- Highly practical methodology for the synthesis of D- and L-α-amino acids, N-protected α-amino acids, and N-methyl-α-amino acids
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Full details are provided for an exceedingly practical method to synthesize D- and L-α-amino acids, N-protected α-amino acids, and N-methyl-α-amino acids, employing as a key step the asymmetric alkylation of pseudoephedrine glycinamide (1) or pseudoephedrine sarcosinamide (2). Practical procedures for the synthesis of 1 and 2 from pseudoephedrine and glycine methyl ester or sarcosine methyl ester, respectively, are presented. Optimum protocols for the enolization and subsequent alkylation of 1 and 2 are described. Alkylation reactions of 1 and 2 are found to be quite efficient with a wide range of alkyl halide substrates, and the products are formed with high diastereoselectivity. The products of these alkylation reactions are hydrolyzed efficiently and with little to no racemization simply by heating in water or water-dioxane mixtures. This protocol provides an exceedingly practical method for the preparation of salt-free α-amino acids of high enantiomeric purity. Alternatively, the alkylation products may be hydrolyzed in high yield and with little to no racemization by heating with aqueous sodium hydroxide. The alkaline hydrolyzate can then be treated with an acylating reagent to provide directly highly enantiomerically enriched N-protected derivatives such as N-Boc and N-Fmoc. Key features necessary for the successful execution of these experimental procedures are identified.
- Myers, Andrew G.,Gleason, James L.,Yoon, Taeyoung,Kung, Daniel W.
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p. 656 - 673
(2007/10/03)
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- Photocatalytic Racemization of Amino Acids in Aqueous Polycrystalline Cadmium(II) Sulfide Dispersions
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L-Lysine in an aqueous solution is partly racemized by photoirradiation (at wavelengths > 300 nm) in the presence of suspended cadmium(II) sulfide particles under a de-aerated atmosphere at room temperature.Loading of a small amount of platinum or its oxide inhibited the racemization, but enhanced N-cyclization of L-lysine into DL-pipecolinic acid. 2H and 1H NMR measurements of the racemate from photoirradiated reaction mixtures in deuterium oxide solutions revealed the substitution of the α-hydrogen of lysine with deuterium alongside the racemization.These facts suggest a mechanism for photocatalytic racemization that includes both reduction and oxidation by photoexcited electrons and positive holes, respectively.Similarly, the other amino acids, leucine and phenylalanine, undergo photocatalytic racemization under reaction conditions where the α-amino group is deprotonated, although glutamic acid gives no racemate during photocatalytic decomposition.Among the CdS photocatalysts used in this study, well grown cubic crystallites with a specific surface area of ca. 8 m2 g-1 showed the highest selectivity for the racemization of L-lysine.
- Ohtani, Bunsho,Kawaguchi, Jun-ichi,Kozawa, Masami,Nishimoto, Sei-ichi,Inui, Tomoyuki,Izawa, Kunisuke
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p. 1103 - 1110
(2007/10/02)
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- Antiatherosclerotic and antithrombotic 2-amino-6-phenyl-4H-pyran-4-ones
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This invention relates to compounds of Formula I STR1 which are useful as antiatherosclerotic agents and inhibitors of cell proliferation for the treatment of proliferative diseases. In addition, various compounds of Formula I are useful inhibitors of platelet aggregation.
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- An Improved Synthesis of Homoproline and Derivatives
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An improved, general synthesis of substituted homoprolines has been developed by using readily available substituted pyridines (1).A key step in this synthetic procedure involves the known conversion of pyridine-N-oxides to 2-cyanopyridines (3) in nearly quantitative yields.The resulting nitriles are hydrolyzed to the corresponding pyridine-2-carboxylic acids (4).Subsequent reduction of the aromatic ring with PtO2/H2 gives the homoprolines (5) in good yields as racemic cis isomers.This procedure also can be utilized for the preparation of 5,6-benzohomoprolines fromthe appropriate quinoline precursors.The N-tert-butyloxycarbonyl (Boc) derivatives of these amino acids (useful intermediates for peptide synthesis) were also prepared in good yields.
- Shuman, Robert T.,Ornstein, Paul L.,Paschal, Jonathan W.,Gesellchen, Paul D.
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p. 738 - 741
(2007/10/02)
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- Trifluoromethyl substituted tetracyclic quinazolin-ones having tranquilizing activity
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Trifluoromethyl substituted tetracyclic compounds including optical isomers thereof having the formula: STR1 wherein n is 1 or 2 and p is 0 or 1, are useful as CNS agents with tranquilizing effects.
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- SHORT- STEP SYNTHESIS OF AMINO ACIDS AND N-HYDROXYAMINO ACIDS FROM AMINES
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Catalytic oxidation of secondary amines with hydrogen peroxide followed by treatment with hydrogen cyanide gave α-cyanohydroxylamines (1).Hydrolysis of 1 gave N-hydroxyamino acids (2), which undergo catalytic hydrogenation to give amino acids (3).This is a simple, efficient, and inexpensive method for synthesis of amino acids from amines.
- Murahashi, Shun-Ichi,Shiota, Tatsuki
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p. 6469 - 6472
(2007/10/02)
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- Tetrapyrrole therapeutic agents
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This invention relates to new fluorescent mono, di- or polyamide of an aminomonocarboxylic acid and a tetrapyrrole containing at least three carboxy groups of the structure: STR1 wherein Z is the amino acid residue and x is the tetrapyrrole residue and "n" is an integer from 1 to 4 inclusive.
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- PYRYLIUM-MEDIATED TRANSFORMATIONS OF NATURAL PRODUCTS. PART 7. DISPLACEMENT OF THE N-SUBSTITUENTS OF PYRIDINIUM IONS IN AQUEOUS SOLUTION: REPLACEMENT OF THE ω-AMINO GROUP OF LYSINE, AND OF THE TERMINAL AMINO GROUP OF GLYCYLGLYCINE
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In two-step sequences, lysine has been converted into the thio-substituted derivatives RS4CH(NH2)CO2H (R=Ph or PhCH2), and glycylglycine into PhSCH2CONHCH2CO2H.All reactions proceeded in aqueous solution at /= 75 deg C; they thus provide models for the selective conversion of proteins at the ω-amino groups of lysine side chains and at the terminal amino groups, respectively.
- Katritzky, Alan R.,Yang, Yu-Kun
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p. 885 - 890
(2007/10/02)
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- Aminosaeuren, I. Darstellung von Aminosaeuren aus Halogencarbonsaeure-alkylestern mit Alkalimetallcyanaten
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α- and ω-halo- as well as α,ω-dihalocarboxylic alkyl esters react with potassium cyanate in the presence of alcohol at 80 - 120 deg C in dipolar aprotic solvents to yield α- and ω-(alkoxycarbonylamino)- and α,ω-bis(alkoxycarbonylamino)carboxylic alkyl esters, respectively, in good yields.Hydrolytic cleavage of these mono- or diurethanes with an aqueous solution of hydrochloric acid/formic acid leads to the corresponding amino acid hydrochlorides in nearly quantitative yields.
- Effenberger, Franz,Drauz, Karlheinz,Foerster, Siegfried,Mueller, Wolfgang
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p. 173 - 189
(2007/10/02)
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- NEW SYNTHESIS OF PIPECOLIC ACID AND ANALOGS
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Pipecolic acid congeners are synthesised from α-cyanoamides, obtained by substitution of α-methoxyamides with trimethylsilyl cyanide and in an alternative route via oxidation of amidoalkylationproducts of the α-methoxyamides.
- Asher, Vikram,Becu, Christian,Anteunis, Marc J. O.,Callens, Roland
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p. 141 - 144
(2007/10/02)
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- Alicyclic Nitrosamines and Nitrosamino Acids as Transnitrosating Agents
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Many alicyclic nitrosamines act as nitrosating agents under mild conditions (pH 1-3, in the presence of nucleophilic catalysts such as thiocyanate).All nitrosopiperazines, nitrosomorpholines, and nitrosamino acids tested were found to act as nitrosating agents, and certain nitrosopiperidines also showed this capability.Acyclic nitrosamines are far less reactive than functionally similar cyclic compounds.
- Singer, Sandra S.,Singer, George M.,Cole, Barbara B.
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p. 4931 - 4935
(2007/10/02)
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- ORIENTATION OF CARBOXYLATION REACTION BY CONTACT GLOW DISCHARGE ELECTROLYSIS
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The carboxylation reaction of aliphatic amines and cyclic imines in aqueous formic acid by contact glow discharge electrolysis (CDGE) was studied and the orientation of the carboxylation reaction was investigated.It was found that orientation of the reaction was controlled by the effect of the charged and uncharged nitrogen atom.
- Terasawa, Jun-ichi,Harada, Kaoru
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- Synthesis of d,1-lysine from 2-cyanopyridine
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A process for the preparation of d,1-lysine wherein 2-cyanopyridine is hydrolyzed to picolinamide, the picolinamide is hydrogenated to pipecolamide, the pipecolamide is converted to 1-acetyl-2-cyanopiperidine, the 1-acetyl-2-cyanopiperidine is then converted to a compound which is hydrolyzed to d,1-lysine.
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