- Catalytic Asymmetric Hydrogenation of Dehydroamino Acid Esters with Biscarbamate Protection and Its Application to the Synthesis of xCT Inhibitors
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Catalytic asymmetric hydrogenation of dehydroamino acid esters with biscarbamate protection was examined for the first time to prepare optically active amino acids. The new method was successfully applied to the synthesis of new cystine–glutamate exchanger inhibitors.
- Yasuno, Yoko,Mizutani, Iho,Sueuchi, Yuki,Wakabayashi, Yuuka,Yasuo, Nozomi,Shimamoto, Keiko,Shinada, Tetsuro
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Read Online
- Novel intermolecular carbon radical addition to a nitrone: asymmetric synthesis of alpha-amino acids.
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A nitrone was used as a synthetically useful radical acceptor in carbon-carbon bond-forming radical reactions; the intermolecular addition of alkyl radicals to chiral glyoxylic nitrone was studied; a high degree of stereocontrol in radical addition to glyoxylic nitrone was achieved to provide a new method for asymmetric synthesis of alpha-amino acids.
- Ueda, Masafumi,Miyabe, Hideto,Teramachi, Masako,Miyata, Okiko,Naito, Takeaki
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Read Online
- Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
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Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
- Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
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supporting information
p. 390 - 398
(2021/01/13)
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- Simultaneous Preparation of (S)-2-Aminobutane and d -Alanine or d -Homoalanine via Biocatalytic Transamination at High Substrate Concentration
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(S)-2-Aminobutane, d-alanine, and d-homoalanine are important intermediates for the production of various active pharmaceutical ingredients and food additives. The preparation of these small chiral amine or amino acids with high water solubility still demands searching for efficient methods. In this work, we identified an ω-transaminase (ω-TA) from Sinirhodobacter hungdaonensis (ShdTA) that catalyzed the kinetic resolution of racemic 2-aminobutane at a concentration of 800 mM using pyruvate as the amino acceptor, leading to the simultaneous isolation of enantiopure (S)-2-aminobutane and d-alanine in 46% and 90% yield, respectively. In addition, (S)-2-aminobutane (98% ee) and d-homoalanine (99% ee) were isolated in 45% and 93% yield, respectively, in the kinetic resolution of racemic 2-aminobutane at a concentration of 400 mM coupled with deamination of l-threonine by threonine deaminase. We thus developed a biocatalytic process for the practical synthesis of these valuable small chiral amine and d-amino acids.
- Li, Jianjiong,Wang, Yingang,Wu, Qiaqing,Yao, Peiyuan,Yu, Shanshan,Zhu, Dunming
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supporting information
(2022/03/01)
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- Zelkovamycins B-E, Cyclic Octapeptides Containing Rare Amino Acid Residues from an Endophytic Kitasatospora sp
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Four unusual cyclopeptides, zelkovamycins B-E (1-4), were isolated from an endophytic Kitasatospora sp. Zelkovamycin B was featured by an unprecedented 3-methyl-5-hydroxypyrrolidine-2,4-dione ring system linked to the cyclopeptide skeleton. Their structures and full configurations were established by spectroscopic analysis, Marfey's method, and NMR calculations. A plausible biosynthetic pathway for zelkovamycins was proposed based on gene cluster analysis. Zelkovamycin E displayed potent inhibitory activity against H1N1 influenza A virus.
- Cen, Shan,Connolly, Jack A.,Gan, Maoluo,Goss, Rebecca J. M.,Hao, Xiaomeng,Liu, Yufeng,Wang, Yujia,Yu, Jiaqing,Yu, Liyan,Zhang, Yuqin
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p. 9346 - 9350
(2020/12/21)
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- Biocatalytic Cascade Reaction for the Asymmetric Synthesis of L- and D-Homoalanine
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Unnatural amino acids attract growing attention for pharmaceutical applications as they are useful building blocks for the synthesis of a number of chiral drugs. Here, we describe a two-step enzymatic method for the asymmetric synthesis of homoalanine from L-methionine, a cheap and readily available natural amino acid. First, the enzyme L-methionine γ-lyase (METase), from Fusobacterium nucleatum, catalyzed the γ-elimination of L-methionine to 2-oxobutyrate. Second, an amino acid aminotransferase catalyzed the asymmetric conversion of 2-oxobutyrate to either L- or D-homoalanine. The L-branched chain amino acid aminotransferase from Escherichia coli (eBCAT), using L-glutamate as amino donor, produced L-homoalanine (32.5 % conv., 28 % y, 99 % ee) and the D-amino acid aminotransferase from Bacillus sp. (DATA) used D-alanine as amino donor to produce D-homoalanine (87.5 % conv., 69 % y, 90 % ee). Thus, this concept allows for the first time the synthesis of both enantiomers of this important unnatural amino acid.
- Silva, Marcus V. de M.,Costa, Ingrid C. R.,de Souza, Rodrigo O. M. A.,Bornscheuer, Uwe T.
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p. 407 - 411
(2018/11/01)
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- Enantioselective Synthesis of d- and l-α-Amino Acids by Enzymatic Transamination Using Glutamine as Smart Amine Donor
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Enzymatic transamination is a useful method for the green and highly enantioselective synthesis of chiral amines and non-canonical amino acids which are of major importance as intermediates in medicinal chemistry. However, transamination reactions are usually reversible and synthetic applications of transaminases often require the implementation of an equilibrium shift strategy. Herein, we report a highly effective approach using glutamine as smart amine donor. This amino acid is converted upon transamination into 2-oxoglutaramate which undergoes a fast cyclisation displacing the transamination equilibrium. We have developed a new activity assay in order to identify transaminases from biodiversity able to convert various α-keto acids into valuable amino acids of l- or d-series in the presence of glutamine as amine donor. Discovered transaminases were then used to prepare in high yield and with high enantioselectivity three amino acids of pharmaceutical importance, homophenylalanine, homoalanine and tert-leucine by simply using a nearly stoichiometric amount of glutamine as amine donor. (Figure presented.).
- Heuson, Egon,Charmantray, Franck,Petit, Jean-Louis,de Berardinis, Véronique,Gefflaut, Thierry
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supporting information
p. 778 - 785
(2019/01/04)
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- One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and Ω-Transaminase
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d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and ω-transaminase and (2) regeneration of NAD+ by NADH oxidase. Under the cascade reaction conditions containing 100?mM isopropylamine and 1?mM NAD+, complete deracemization of 100?mM dl-alanine was achieved after 24?h with 95% reaction yield of d-alanine (> 99% eeD, 52% isolation yield). Graphical Abstract: [Figure not available: see fulltext.].
- Han, Sang-Woo,Shin, Jong-Shik
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p. 3678 - 3684
(2018/10/20)
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- Structure-guided engineering of: Meso -diaminopimelate dehydrogenase for enantioselective reductive amination of sterically bulky 2-keto acids
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meso-Diaminopimelate dehydrogenase (DAPDH) and mutant enzymes are an excellent choice of biocatalysts for the conversion of 2-keto acids to the corresponding d-amino acids. However, their application in the enantioselective reductive amination of bulky 2-keto acids, such as phenylglyoxylic acid, 2-oxo-4-phenylbutyric acid, and indole-3-pyruvic acid, is still challenging. In this study, the structure-guided site-saturation mutagenesis of a Symbiobacterium thermophilum DAPDH (StDAPDH) gave rise to a double-site mutant W121L/H227I, which showed dramatically improved enzyme activities towards various 2-keto acids including these sterically bulky substrates. Several d-amino acids were prepared in optically pure form. The molecular docking of substrates into the active sites of wild-type and mutant W121L/H227I enzymes revealed that the substrate binding cavity of the mutant enzyme was reshaped to accommodate these bulky substrates, thus leading to higher enzyme activity. These results lay a foundation for further shaping the substrate binding pocket and manipulating the interactions between the substrate and binding sites to access highly active d-amino acid dehydrogenases for the preparation of synthetically challenging d-amino acids.
- Cheng, Xinkuan,Chen, Xi,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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p. 4994 - 5002
(2018/10/17)
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- Highly atom economic synthesis of D-2-aminobutyric acid through an in vitro tri-enzymatic catalytic system
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D-2-Aminobutyric acid is an unnatural amino acid serving as an important intermediate in pharmaceutical production. Developing a synthetic method that uses cheaper starting materials and produces less by-product is a pressing demand. A tri-enzymatic catalytic system, which is composed of L-threonine ammonia lyase (L-TAL), D-amino acid dehydrogenase (D-AADH), and formate dehydrogenase (FDH), has thus been developed for the synthesis of D-2-aminobutyric acid with high optical purity. In this cascade reaction, the readily available L-threonine serves as the starting material, carbon dioxide and water are the by-products. D-2-Aminobutyric acid was obtained with >90% yield and >99% enantioselective excess, even without adding external ammonia, demonstrating that the ammonia from the first reaction can serve as the amino donor for the reductive amination step. This multi-enzymatic system provides an attractive method with high atomic economy for the synthesis of D-α-amino acids from the corresponding L-α-amino acids, which are readily produced by fermentation.
- Chen, Xi,Cui, Yunfeng,Cheng, Xinkuan,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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p. 534 - 540
(2018/08/17)
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- METHOD OF PRODUCING D-THREONINE AND HOMOALANINE FROM RACEMIC THREONINE
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Provided is a method for producing D-threonine in a simple way using bio-enzyme. Also, provided is a method for producing homoalanine in high yield from 2-oxobutyrate produced in addition to D-threonine. To this end, the method of the present invention comprises the following steps: (a) producing D-threonine and 2-oxobutyrate from DL-threonine via kinetic resolution involving L-threonine dehydratase; and (b) producing optically pure L-/D-homoalanine using (S)- or (R)-selective omega-transaminase from the 2-oxobutyrate.COPYRIGHT KIPO 2016
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Paragraph 0058-0059
(2017/04/14)
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- Pinensins: The First Antifungal Lantibiotics
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Lantibiotics (lanthionine-containing antibiotics) from Gram-positive bacteria typically exhibit activity against Gram-positive bacteria. The activity and structure of pinensin A (1) and B (2), lantibiotics isolated from a native Gram-negative producer Chitinophaga pinensis are described. Surprisingly, the pinensins were found to be highly active against many filamentous fungi and yeasts but show only weak antibacterial activity. To the best of our knowledge, lantibiotic fungicides have not been described before. An in-depth bioinformatic analysis of the biosynthetic gene cluster established the ribosomal origin of these compounds and identified candidate genes encoding all of the enzymes required for post-translational modification. Additional encoded functions enabled us to build up a hypothesis for the biosynthesis, export, sensing, and import of this intriguing lantibiotic.
- Mohr, Kathrin I.,Volz, Carsten,Jansen, Rolf,Wray, Victor,Hoffmann, Judith,Bernecker, Steffen,Wink, Joachim,Gerth, Klaus,Stadler, Marc,Müller, Rolf
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supporting information
p. 11254 - 11258
(2016/07/06)
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- Preparation of d-threonine by biocatalytic kinetic resolution
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D-Threonine is one of the important unnatural amino acids used as chiral building blocks in pharmaceutical drugs. Owing to the presence of two chiral centers, a synthetic protocol, either through chemocatalysis or biocatalysis, has not yet been available for one-step preparation of stereochemically pure d-threonine in terms of enantiomeric and diastereomeric excesses (i.e., both >99%). Here we demonstrate that facile production of d-threonine can be implemented using threonine deaminase (TD) via kinetic resolution of dl-threonine that can be readily prepared by conventional organic synthesis. TD catalyzes the dehydration/deamination of l-threonine, leading to generation of 2-oxobutyrate and ammonia. In contrast to mild substrate inhibition of the TD activity by l-threonine (i.e., apparent inhibition constant (KIapp) = 950 mM), d-threonine turned out to be a strong inhibitor (i.e., KIapp = 41 mM). In addition to the enzyme inhibitions by both enantiomers of threonine, cell lysis observed during small-scale kinetic resolutions of ≥1 M dl-threonine led us to carry out a preparative-scale reaction at 500 mM racemic substrate. The preparative-scale kinetic resolution in a 50 mL reaction mixture charged with 3 g dl-threonine and 3400 U whole cells was completed at 5 h with >99% ee of d-threonine. Product isolation by a cation-exchange chromatography led to white solid of d-threonine (1.36 g, 90.7% isolation yield). To explore whether our strategy could afford coproduction of another valuable unnatural amino acid, the pass-through solution from the cation-exchange column was further processed by a ω-transaminase (ω-TA) reaction where 2-oxobutyrate was converted to enantiopure homoalanine using isopropylamine as an amino donor. Addition of S- and R-selective ω-TA to the pass-through solution led to 93.2 and 90.9% reaction yield within 12 h with both >99% ee of the produced l- and d-homoalanine, respectively.
- Han, Sang-Woo,Shin, Jong-Shik
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p. 227 - 232
(2015/10/28)
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- Deracemization of amino acids by coupling transaminases of opposite stereoselectivity
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Biocatalytic deracemization of amino acids without relying on oxidase-based deamination of an unwanted enantiomer was demonstrated by coupling a-and w-transaminases displaying opposite stereoselectivity. This strategy employs isopropylamine and a keto acid as cosubstrates and is free of generation of hydrogen peroxide which is troublesome in the conventional oxidase-based methods.
- Park, Eul-Soo,Shin, Jong-Shik
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p. 3505 - 3509
(2015/02/19)
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- A green and expedient synthesis of enantiopure diketopiperazines via enzymatic resolution of unnatural amino acids
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Dipeptides comprising a d-phenylglycyl moiety coupled to the l-enantiomer of 2-amino butyric acid, norvaline, norleucine, and homocysteine were successfully synthesized from d-phenylglycine amide and the racemate of the corresponding unnatural amino acid.
- Pereira, Pedro C.,Arends, Isabel W.C.E.,Sheldon, Roger A.
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supporting information
p. 4991 - 4993
(2015/01/09)
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- Characterization of d-amino acid aminotransferase from Lactobacillus salivarius
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We searched a UniProt database of lactic acid bacteria in an effort to identify d-amino acid metabolizing enzymes other than alanine racemase. We found a d-amino acid aminotransferase (d-AAT) homologous gene (UniProt ID: Q1WRM6) in the genome of Lactobacillus salivarius. The gene was then expressed in Escherichia coli, and its product exhibited transaminase activity between d-alanine and α-ketoglutarate. This is the first characterization of a d-AAT from a lactic acid bacterium. L. salivarius d-AAT is a homodimer that uses pyridoxal-5′-phosphate (PLP) as a cofactor; it contains 0.91 molecules of PLP per subunit. Maximum activity was seen at a temperature of 60 °C and a pH of 6.0. However, the enzyme lost no activity when incubated for 30 min at 30 °C and pH 5.5 to 9.5, and retained half its activity when incubated at pH 4.5 or 11.0 under the same conditions. Double reciprocal plots of the initial velocity and d-alanine concentrations in the presence of several fixed concentrations of α-ketoglutarate gave a series of parallel lines, which is consistent with a Ping-Pong mechanism. The Km values for d-alanine and α-ketoglutarate were 1.05 and 3.78 mM, respectively. With this enzyme, d-allo-isoleucine exhibited greater relative activity than d-alanine as the amino donor, while α-ketobutylate, glyoxylate and indole-3-pyruvate were all more preferable amino acceptors than α-ketoglutarate. The substrate specificity of L. salivarius d-AAT thus differs greatly from those of the other d-AATs so far reported.
- Kobayashi, Jyumpei,Shimizu, Yasuhiro,Mutaguchi, Yuta,Doi, Katsumi,Ohshima, Toshihisa
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- ω-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor
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Isopropylamine is an ideal amino donor for reductive amination of carbonyl compounds by ω-transaminase (ω-TA) owing to its cheapness and high volatility of a ketone product. Here we developed asymmetric synthesis of unnatural amino acids via ω-TA-catalyzed amino group transfer between α-keto acids and isopropylamine.
- Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 6929 - 6933
(2013/10/08)
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- Chemical approach for interconversion of (S)- and (R)-α-amino acids
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Here we report a general method for the preparation of unnatural (R)-α-amino acids via complexation of α-(phenyl)ethylamine derived chiral reagent (S)-3 with various (S)-α-amino acids. The reactions proceed with synthetically useful chemical yields and thermodynamically controlled diastereoselectivity. Chiral reagent (S)-3 can be conveniently recovered and reused without any loss of enantiomeric purity and reactivity. The Royal Society of Chemistry 2013.
- Sorochinsky, Alexander E.,Ueki, Hisanori,Ace?a, José Luis,Ellis, Trevor K.,Moriwaki, Hiroki,Sato, Tatsunori,Soloshonok, Vadim A.
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p. 4503 - 4507
(2013/08/23)
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- Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
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Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright
- Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 3538 - 3542
(2014/01/06)
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- ω-Transaminase-catalyzed kinetic resolution of chiral amines using l-threonine as an amino acceptor precursor
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Kinetic resolution of chiral amines using l-threonine as a cosubstrate was demonstrated by a biocatalytic strategy in which (S)-selective ω-transaminase (ω-TA) was coupled with threonine deaminase (TD), eliminating the need to use an expensive keto acid as an amino acceptor. The coupled enzyme reaction enabled simultaneous production of enantiopure (R)-amine and l-homoalanine which are pharmaceutically important building blocks. To extend the versatility of this strategy to production of both enantiomers of chiral amines, (R)-selective ω-TA coupled with TD was employed to produce (S)-amine.
- Malik, M. Shaheer,Park, Eul-Soo,Shin, Jong-Shik
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supporting information; experimental part
p. 2137 - 2140
(2012/09/25)
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- Dynamic kinetic resolution of α-aminonitriles to form chiral α-amino acids
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We have succeeded in the enzymatic synthesis of (R)-α-aminobutyric acid from racemic α-aminobutyronitrile. This has been demonstrated by the use of non-stereoselective nitrile hydratase (NHase) from Rhodococcus opacus 71D, D-aminopeptidase from Ochrobactrum anthropi C1-38 and α-amino-ε- caprolactam (ACL) racemase from Achromobacter obae. Racemic α- aminobutyronitrile was completely converted in 6 h at 30 °C to (R)-α-aminobutyric acid whose optical purity was more than 99%. (S)-α-Aminobutyric acid was also synthesized from α- aminobutyronitrile by NHase, ACL racemase and L-amino acid amidase from Brevundimonas diminuta TPU 5720. In a similar manner, other (R)- or (S)-α-amino acids with more than 97.5% ee could be synthesized from the corresponding α-aminonitriles. This is the first report on the dynamic kinetic resolution (DKR) of α-aminonitriles to form chiral α-amino acids. The key enzyme in this DKR is non-stereoselective NHase, which had been newly screened from soil samples, and its gene cloned. Copyright
- Yasukawa, Kazuyuki,Hasemi, Ryuji,Asano, Yasuhisa
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experimental part
p. 2328 - 2332
(2011/10/19)
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- Grassypeptolides A-C, cytotoxic bis-thiazoline containing marine cyclodepsipeptides
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Grassypeptolides A-C (1-3), a group of closely related bis-thiazoline containing cyclic depsipeptides, have been isolated from extracts of the marine cyanobacterium Lyngbya confervoides. Although structural differences between the analogues are minimal, comparison of the in vitro cytotoxicity of the series revealed a structure-activity relationship. When the ethyl substituent of 1 is changed to a methyl substituent in 2, activity is only slightly reduced (3-4-fold), whereas inversion of the Phe unit flanking the bis-thiazoline moiety results in 16-23-fold greater potency. We show that both 1 and 3 cause G1 phase cell cycle arrest at lower concentrations, followed at higher concentrations by G2/M phase arrest, and that these compounds bind Cu2+ and Zn 2+. The three-dimensional structure of 2 was determined by MS, NMR, and X-ray crystallography, and the structure of 3 was established by MS, NMR, and chemical degradation. The structure of 3 was explored by in silico molecular modeling, revealing subtle differences in overall conformation between 1 and 3. Attempts to interconvert 1 and 3 with base were unsuccessful, but enzymatic conversion may be possible and could be a novel form of activation for chemical defense.
- Kwan, Jason C.,Ratnayake, Ranjala,Abboud, Khalil A.,Paul, Valerie J.,Luesch, Hendrik
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experimental part
p. 8012 - 8023
(2011/03/20)
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- METHOD OF SEPARATING AND COLLECTING OPTICALLY ACTIVE AMINO ACID AMIDE
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[PROBLEMS] To provide a method of efficiently separating and collecting an optically active amino acid amide and an optically active amino acid, which are highly important substances as intermediates in producing various industrial products, pesticides and medicines, from an aqueous solution containing the optically active amino acid amide and the optically active amino acid. [MEANS FOR SOLVING PROBLEMS] In separating and collecting an optically active amino acid amide from an aqueous solution containing the optically active amino acid amide and an optically active amino acid by using the difference in solubility in an organic solvent between the optically active amino acid amide and the optically active amino acid, the separation/collection procedures are carried out, without desalting the aqueous solution or after desalting the same, under such conditions that the ratio (C/A) of the sum of the anionic equivalents (A) contained in the aqueous solution to the sum of the cation equivalents (C) ranges from 0.95 to 1.05 in the case of the non-desalted aqueous solution, or from 0.5 to 1.5 in the case of the desalted aqueous solution.
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Page/Page column 11-12;13
(2008/06/13)
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- COMBINATIONS FOR THE TREATMENT OF DISEASES INVOLVING CELL PROLIFERATION
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The present invention relates to a pharmaceutical composition for the treatment of diseases which involve cell proliferation. The invention also relates to a method for the treatment of said diseases, comprising co-administration of a compound 1 of Formula (I) wherein the groups L, R1, R2, R3, R4 and R5 have the meanings given in the claims and specification, optionally in form of its tautomers, racemates, enantiomers, diastereomers and the mixtures thereof and optionally in form of the pharmacologically acceptable acid addition salts, solvates, hydrates, polymorphs, physiologically functional derivatives or prodrugs thereof, and of an effective amount of an active compound 2 and/or co-treatment with radiation therapy, in a ratio which provides an additive and synergistic effect, and to the combined use of a compound 1 of Formula (I) and of an effective amount of an active compound 2 and/or radiotherapy for the manufacture of corresponding pharmaceutical combination preparations.
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Page/Page column 63
(2008/06/13)
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- DIHYDROPTERIDINONES FOR THE TREATMENT OF CANCER DISEASES
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The present invention relates to the use of a compound of general Formula (1), optionally in form of its tautomers, racemates, enantiomers, diastereomers and the mixtures thereof and optionally in form of the pharmacologically acceptable acid addition salts, solvates, hydrates, polymorphs, physiologically functional derivatives or prodrugs thereof, for the preparation of a pharmaceutical composition for the treatment of diseases characterized by abnormal cell proliferation in a human or non-human mammalian body by inhibition of polo like kinases as mitotic regulators.
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Page/Page column 63
(2008/06/13)
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- Creation of a broad-range and highly stereoselective D-amino acid dehydrogenase for the one-step synthesis of D-amino acids
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Using both rational and random mutagenesis, we have created the first known broad substrate range, nicotinamide cofactor dependent, and highly stereoselective D-amino acid dehydrogenase. This new enzyme is capable of producing D-amino acids via the reductive amination of the corresponding 2-keto acid with ammonia. This biocatalyst was the result of three rounds of mutagenesis and screening performed on the enzyme meso-diaminopimelate D-dehydrogenase. The first round targeted the active site of the wild-type enzyme and produced mutants that were no longer strictly dependent on the native substrate. The second and third rounds produced mutants that had an increased substrate range including straight-and branched-aliphatic amino acids and aromatic amino acids. The very high selectivity toward the D-enantiomer (95 to >99% ee) was shown to be preserved even after the addition of the five mutations found in the three rounds of mutagenesis and screening. This new enzyme could complement and improve upon current methods for D-amino acid synthesis.
- Vedha-Peters, Kavitha,Gunawardana, Manjula,Rozzell, J. David,Novick, Scott J.
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p. 10923 - 10929
(2007/10/03)
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- Resolution of non-protein amino acids via the microbial protease-catalyzed enantioselective hydrolysis of their N-unprotected esters
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In the Aspergillus oryzae protease-catalyzed ester hydrolysis, substitution of N-unprotected amino acid esters for the corresponding N-protected amino acid esters resulted in a large enhancement of the hydrolysis rate, while the enantioselectivity was deteriorated strikingly when the substrates employed were the conventional methyl esters. This difficulty was overcome by employing esters bearing a longer alkyl chain such as the isobutyl ester. Utilizing this ester, amino acids carrying an aromatic side chain were resolved with excellent enantioselectivities (E=50 to >200). With amino acids bearing an aliphatic side chain also, good results in terms of the hydrolysis rate and enantioselectivity were obtained by employing such an ester as the isobutyl ester. Moreover, the enantioselectivity proved to be enhanced further by conducting the reaction at low temperature. This procedure was applicable to the case where the enantioselectivity was not high enough even by the use of the isobutyl ester.
- Miyazawa, Toshifumi,Imagawa, Kiwamu,Minowa, Hiroe,Miyamoto, Toyoko,Yamada, Takashi
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p. 10254 - 10261
(2007/10/03)
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- Diastereoselective intermolecular radical addition to nitrones
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The intermolecular radical addition to chiral nitrones 2, 4, 5, and 16 was studied. The isopropyl radical addition to Oppolzer's camphorsultam derivative 2 of glyoxylic nitrone proceeded with excellent diastereoselectivity to give the desired isopropylated product 3a accompanied by the diisopropylated product 3b. A high degree of stereocontrol in the reaction of cyclic nitrone 4 was achieved. The ethyl radical addition to nitrone 4 with triethylborane afforded the desired ethylated product 9a accompanied by the diethylated product 10a and the ethylated nitrone 11a. To evaluate the utility of cyclic nitrone 4, several alkyl radicals were employed in the addition reaction, which afforded the alkylated products 9b-d with excellent diastereoselectivities. In the presence of Mg(ClCO4)2, the ethyl radical addition to BIGN 16 afforded selectively syn isomers. In contrast, the alkyl radical addition to 16 took place even in the absence of Lewis acid to give anti isomers.
- Ueda, Masafumi,Miyabe, Hideto,Teramachi, Masako,Miyata, Okiko,Naito, Takeaki
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p. 6653 - 6660
(2007/10/03)
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- Application of aminoacylase I to the enantioselective resolution of α-amino acid esters and amides
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Aminoacylase I from Aspergillus melleus, a readily available and inexpensive enzyme mainly used in the industrial production of enantiopure L-amino acids from their N-acetyl derivatives, is shown to hydrolyze the esters and amides of natural and non-natural amino acids with high enantioselectivity (for the ester hydrolysis, E is up to 76, in case of amides E >300). The reaction rates of amide and ester hydrolysis are comparable, and in some cases these conversions proceeded even faster than 'traditional' aminoacylase- catalyzed hydrolysis of N-acetyl derivatives thus providing new possibilities for the resolution of the corresponding racemates. This novel approach provides an alternative route for the biocatalytic production of optically active amino acids and their derivatives.
- Youshko, Maxim I.,Van Langen, Luuk M.,Sheldon, Roger A.,Svedas, Vytas K.
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p. 1933 - 1936
(2007/10/03)
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- Synthesis of α-Amino Acids via Asymmetric Phase Transfer-Catalyzed Alkylation of Achiral Nickel(II) Complexes of Glycine-Derived Schiff Bases
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Achiral, diamagnetic Ni(II) complexes 1 and 3 have been synthesized from Ni(II) salts and the Schiff bases, generated from glycine and PBP (7) and PBA (11), respectively, in MeONa/MeOH solutions. The requisite carbonyl-derivatizing agents pyridine-2-carboxylic acid(2-benzoyl-phenyl)-amide 7 (PBP) and pyridine-2-carboxylic acid(2-formyl-phenyl)-amide 11 (PBA) were readily prepared from picolinic acid and o-aminobenzophenone or picolinic acid and methyl o-anthranilate, respectively. The structure of 1 was established by X-ray crystallography. Complexes 1 and 3 were found to undergo C-alkylation with alkyl halides under PTC conditions in the presence of β-naphthol or benzyltriethylammonium bromide as catalysts to give mono- and bis-alkylated products, respectively. Decomposition of the complexes with aqueous HCI under mild conditions gave the required amino acids, and PBP and PBA were recovered. Alkylation of 1 with highly reactive alkyl halides, carried out under the PTC conditions in the presence of 10% mol of (S)- or (R)-2-hydroxy-2′ -amino-1,1′-binaphthyl 31a (NOBIN) and/or its N-acyl derivatives and by (S)- or (R)-2-hydroxy-8′-amino-1,1′-binaphthyl 32a (iso-NOBIN) and its N-acyl derivatives, respectively, gave rise to α-amino acids with high enantioselectivities (90-98.5% ee) in good-to-excellent chemical yields at room temperature within several minutes. An unusually large positive nonlinear effect was observed in these reactions. The Michael addition of acrylic derivatives 37 to 1 was conducted under similar conditions with up to 96% ee. The 1H NMR and IR spectra of a mixture of the sodium salt of NOBIN and 1 indicated formation of a complex between the two components. Implications of the association and self-association of NOBIN for the observed sense of asymmetric induction and nonlinear effects are discussed.
- Belokon, Yuri N.,Bespalova, Natalia B.,Churkina, Tatiana D.,Cisarova, Ivana,Ezernitskaya, Marina G.,Harutyunyan, Syuzanna R.,Hrdina, Radim,Kagan, Henri B.,Kocovsky, Pavel,Kochetkov, Konstantin A.,Larionov, Oleg V.,Lyssenko, Konstantin A.,North, Michael,Polasek, Miroslav,Peregudov, Alexander S.,Prisyazhnyuk, Vladimir V.,Vyskocil, Stepan
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p. 12860 - 12871
(2007/10/03)
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- Study of the reactions between vinylmagnesium bromide and imines derived from (R)-glyceraldehyde - The key step in the stereodivergent synthesis of conveniently protected, enantiopure syn- and anti-2-amino-1,3,4-butanetriol derivatives
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A total stereodivergent method for the synthesis of enantiopure syn- and anti-2-amino-1,3,4-butanetriol (ABT) derivatives from inexpensive and readily available D-mannitol has been developed. Key steps include: (a) the diastereoselective addition of vinylmagnesium bromide to conveniently protected N-benzylimines derived from (R)-glyceraldehyde, and (b) the oxidative degradation of the C-C double bond of the resultant syn- and anti-vinylaminodiol derivatives. The addition of vinylmagnesium bromide in diethyl ether to the N-benzylimine derived from (R)-2,3-O-isopropylideneglyceraldehyde affords the anti-vinylaminodiol derivative, while the reaction with the N-benzylimine derived from (R)-2,3-di-Obenzylglyceraldehyde affords the syn-vinylaminodiol derivative, both with excellent diastereoselectivities (de > 98/2). Moreover, a reversal of the stereochemical course of the reaction is produced when (R)-2,3-O-isopropylideneglyceraldehyde N-benzylimine is precomplexed with ZnI2, in this case yielding the syn addition adduct as the major compound. Different reaction conditions (reagent molar ratio, reaction temperature) have been tested in order to determine their influences on the observed yields and diastereo-selectivities. From the results of this study and a subsequent crossover experiment, some interesting mechanistic considerations can be inferred. Enantiopure anti- and syn-vinylaminodiol adducts have been successfully converted into conveniently protected anti- and syn-2-amino-1,3,4-butanetriol (ABT) derivatives, key building blocks in the asymmetric synthesis of biologically active compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Badorrey, Ramon,Cativiela, Carlos,Diaz-de-Villegas, Maria D.,Diez, Roberto,Galvez, Jose A.
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p. 2268 - 2275
(2007/10/03)
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- Amine-boranes: Effective reducing agents for the deracemisation of DL-amino acids using L-amino acid oxidase from Proteus myxofaciens
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The deracemisation of DL-α-amino acids using L-amino acid oxidase from Proteus myxofaciens and amine-boranes as chemical reducing agents has been investigated. Amine-boranes were found to be of particular interest in terms of reactivity and chemoselectivity compared to sodium borohydride and cyanoborohydride. Starting from the racemate, a range of D-amino acids were obtained in yields of up to 90% and e.e. >99%.
- Alexandre, Fran?ois-René,Pantaleone, David P.,Taylor, Paul P.,Fotheringham, Ian G.,Ager, David J.,Turner, Nicholas J.
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p. 707 - 710
(2007/10/03)
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- Highly efficient catalytic synthesis of α-amino acids under phase-transfer conditions with a novel catalyst/substrate pair
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A facile and fast enantioselective synthesis of α-amino acids with high ee values was achieved by the asymmetric alkylation of the glycine derivative 1 under phase-transfer conditions with (R)-2-amino-2′-hydrozy-1,1′-binaphthyl (NOBIN; see sceme). The ee value of the amino acid products. This occures as a results of a significant positive nonlinear effect in the alkylation reaction.
- Belokon, Yuri N.,Kochetkov, Konstantin A.,Churkina, Tatiana D.,Ikonnikov, Nikolai S.,Larionov, Oleg V.,Harutyunyan, Syuzanna R.,Vyskocil, Stepan,North, Michael,Kagan, Henri B.
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p. 1948 - 1951
(2007/10/03)
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- The imine (+)-pseudoephedrine glycinamide: A useful reagent for the asymmetric synthesis of (R)-α-amino acids
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The new imine derived from Myers (+)-pseudoephedrine glycinamide can be diastereoselectively alkylated with alkyl halides at room temperature using NaOEt or LiO-tert-Bu as bases under phase transfer conditions. Hydrolysis to the corresponding alkylated products was easily achieved under mild conditions to afford (R)-α-amino acids.
- Guillena, Gabriela,Najera, Carmen
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p. 181 - 183
(2007/10/03)
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- Chemo-enzymatic synthesis of optically active amino acids and peptides
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The industrial alkaline protease, alcalase, is stable and active in a high concentration of organic solvents and useful as a biocatalyst for (i) diastereoselective hydrolysis of peptide esters and preparation of racemization-free peptides; (ii) selective incorporation of esters of D-amino acid into peptides in t-butanol via a selective hydrolysis of esters of D,L-amino acid, followed by using the unhydrolyzed D-esters as a nucleophile in a kinetically controlled peptide bond formation; (iii) resolution of esters of amino acid in 95% t-butanol/5% water, followed by saponification of the unreacted esters to offer both enantiomers with high yield and optical purity; (iv) completely resolve amino-acid esters with high yield and optical purity via in situ racemization of the unreacted antipode catalyzed by pyridoxal 5-phosphate; (v) cryobioorganic synthesis of peptides with increased yields 15%-40% of peptide bond formation by reaction at 5 °C instead of 25-30 °C of a kinetically controlled enzymatic reaction in alcohols.
- Chen, Shui-Tein,Wang, Kung-Tsung
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p. 301 - 311
(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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- Synthesis of homochiral α-amino acids by reductive amination of α-ketoacids via 3-substituted-5-phenyl-3,4-dehydromorpholin-2-ones: Synthesis of (S)- and (R)-2-aminobutanoic acid
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2-Oxobutanoic acid has been converted to (R)- or (S)-2-aminobutanoic acid via highly diastereocontrolled hydrogenation of the corresponding homochiral 3-ethyl-5-phenyl-3,4-dehydromorpholin-2-one derivatives.
- Cox,Harwood
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p. 1669 - 1672
(2007/10/02)
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- A New Route to the Synthesis of Amino Acids through the Mercury Cyclization of Chiral Amidals
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By means of the mercury cyclization of the unsaturated amidals 3a-e, obtained from the reaction of 1,3,5-tris-hexahydrotriazine (1) and α,β-unsaturated acyl chlorides, diastereomeric mixtures of imidazolidin-4-ones 5-8 and perihydropyrimidin-4-ones 9-10 have been synthesized and easily separated by flash chromatography.The subsequent hydrolysis under acid conditions of the separated heterocycles affords respectively D or L α- and β-amino acids.The regiochemistry of the cyclization has been studied, depending on the substituents of the double bond.Furthermore the absolute configuration of the newly introduced stereogenic center has been attributed on the basis of the 1H NMR spectra of the heterocycles.
- Amoroso, Rosa,Cardillo, Giuliana,Tomasini, Claudia,Tortoreto, Paola
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p. 1082 - 1087
(2007/10/02)
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- Plasmid-based, D-aminopeptidase-catalysed synthesis of (R)-amino acids
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The gene for D-aminopeptidase from Ochrobactrum anthropi SCRC Cl-38 was cloned in Eschericha coli JM 109.An expression plasmid pCl138DP (4.5 kb) was constructed.The amount of the enzyme in a cell-free extract of E. coli JM109/pCl138DP was elevated up to 288000 units/liter culture, which is about 3600-fold over that of O.anthropi SCRC Cl-38.It was calculated that the enzyme comprised about 30percent of the total extractable cellular protein.The intact cells of the E.coli transformant were used as a catalyst for (R)-stereospecific hydrolysis of several racemic amino amides HCl.Complete hydrolysis of (R)-alanine amide was achieved in a short time (4 1/2 h) from 5.0M racemic alanine amide HCl using cells of the E.coli transformant.The concentration of (R)-alanine reached 220 g/l.The cells or the cell-free extract catalyzed the synthesis of (R)-2-aminobutyric acid, (R)-methionine, (R)-norvaline and (R)-norleucine from their amides in a similar manner.
- Asano, Yasuhisa,Kishino, Katsuhiko,Yamada, Akiko,Hanamoto, Sawako,Kondo, Kiyosi
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p. 206 - 208
(2007/10/02)
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- Asymmetric Syntheses of Amino Acids by Addition of Cyanide to the Schiff Bases in the Presence of Cyanide-Modified Hemin-Copolymer
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Sterically controlled addition reactions of CN group to the Schiff bases by using CN-modified hemin-copolymer were carried out, and the optical yields (80-95 e.e.) of the resulting amino acids were much higher than that obtained without hemin-copolymer.
- Saito, Kiyoshi,Harada, Kaoru
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p. 4535 - 4538
(2007/10/02)
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- Total Asymmetric Transformations at Interfaces with Centrosymmetric Cristals: Role of Hydrophobic and Kinetic Effects in the Crystallization of the System Glycine/α-Amino Acids
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A model of generation and amplification of optical activity, using the centrosymmetric crystals of glycine as substrates for total separation of occluded α-amino acids into enantiomeric territories, is described.The principle is based on the enantioselective occlusion of these additives through the enantiotopic (010) and (00) faces of glycine cristals.Such crystals, when floating at the air/solution interface, and if correctly oriented, may incorporate only one of the two enantiomeric additives present in solution.We demonstrate that complete (010) or (00) orientation may be induced by both kinetic and "hydrophobic" effects.The former is achieved through inhibition of nucleation and growth of the say (010) oriented crystals , by (S) amino acids in solution, while the latter is due to induction of (00) orientation by (S) hydrophobic amino acids.By symmetry the enantiomers induce opposite orientation.The two effects are investigated separately, and possible mechanisms are proposed.Combimation of the two effects, which operate in the same direction, allows total orientation of glycin crystals and thus triggering of amplification starting with a solution containing leucine with an enantiomeric excess as low as 6percent.The relevance of such a mechanism to other systems and to nucleation in general is discussed.
- Weissbuch, I.,Addadi, L.,Leiserowitz, L.,Lahav, M.
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p. 561 - 567
(2007/10/02)
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- Heterogeneous Asymmetric Hydrogenation of a Chiral Tripeptide containing Dehydroalanine and α,β-Dehydrobutyrine Residues
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The heterogeneous asymmetric hydrogenation of a linear tripeptide containing dehydroalanine and α,β-dehydrobutyrine has been carried out, giving asymmetric yields of alanine and butyrine of 94 and 54percent, respectively.
- Takasaki, Michiaki,Harada, Kaoru
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p. 571 - 573
(2007/10/02)
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- Racemic Structures of Organic Ammonium Salts of N-Acetyl-DL-2-aminobutyric Acid and N-Acetyl-DL-norvaline and Optical Resolution by Preferential Crystallization of DL-Ammonium Salts
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The racemic structures of the ammonium salts (AM salts) and seven organic ammonium salts of N-acetyl-DL-2-aminobutyric acid (Dl-AcAbu) and N-acetyl-DL-norvaline (DL-AcNva) were studied on the basis of thermodynamic analyses to explore the possibility of optical resolution by preferential crystallization.An empirical equation has been derived from thermodynamic data and melting points of ammonium and organic ammonium salts of N-acyl-DL-amino acids to predict racemic structure around room temperature.The AM salts of DL-AcAbu and -AcNva exist in conglomerate around room temperature.It is possible to resolve optically these DL-AM salts by preferential crystallization in ethanol at 10 deg C, and the succesive preferential crystallization followed by purification gave D- and L-2-aminobutyric acids and -norvalines with optical purities close to 100percent.
- Shiraiwa, Tadashi,Yoshida, Hirokazu,Tsuda, Makoto,Kurokawa, Hidemoto
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p. 947 - 952
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF α-AMINO ACIDS FROM α-HALOGENATED 10-SULFONAMIDO-ISOBORNYL ESTERS.
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Treatment of chiral α-haloesters 2 with NaN3 gave azidoesters 3 wich on successive transesterification and hydrogenolysis furnished α-amino acids 5 and 9 in high e.e.
- Oppolzer, Wolfgang,Pedrosa, Rafael,Moretti, Robert
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p. 831 - 834
(2007/10/02)
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- Chirospecific Synthesis of (+)-Pilocarpine
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An efficient chirospecific synthesis for (+)-pilocarpine (1a) using D-methionine or D-2-aminobutanol as chiral educt is described.Formation of the C3-C4 carbon bond at an early stage gave the key intermediate diethyl phosphonate.Wittig coupling of this phosphonate with 1-methyl-5-imidazolecarboxaldehyde introduced the imidazole moiety of the pilocarpine skeleton.Selective reduction of an α,β-unsaturated nitrile to the corresponding allylic alcohol, stereocontrolled hydrogenation of the olefin, and epimerization of (+)-isopilocarpine to (+)-pilocarpine via kinetic protonation led to formation of the natural alkaloid.This methodology allows chirospecific syntheses of the four possible stereoisomers of pilocarpine.A short and convenient route to (+/-)-pilocarpine based on the key intermediate phosphonate is also described.
- Compagnone, Reinaldo S.,Rapoport, Henry
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p. 1713 - 1719
(2007/10/02)
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- A General and Practical Synthesis of (R)-Phthalimido Aldehydes and D-α-Amino Acids from D-Mannitol
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A short and practical synthesis of five D-α-amino acids is described from D-mannitol as the chiral educt.The key steps in the sequence are (a) the erythro-selective addition of organometals to (R)-2,3-O-isopropylideneglyceralaldehyde, (b) the Mitsunobu inversion substituting N-phthalimide for hydroxyl, and (c) acetonide hydrolysis and glycol cleavage to give the N -phthaloyl-(R)-α-aminoaldehydes 7.These are oxidized under Jones conditions to give the N-protected amino acids 8.The examples investigated (alanine, aminobutyric acid, norvaline, and allyl- and vinylglycine) demonstrate the general applicability of the method.
- Mulzer, Johann,Angermann, Alfred,Schubert, Boris,Seilz, Carsten
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p. 5294 - 5299
(2007/10/02)
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