- Rhodium-catalysed racemisation of N-acyl α-amino acids
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The first transition metal-catalysed racemisation of N-acyl α-amino acids, which is of importance for kinetic resolution processes, is described. Enantiomerically pure N-acyl α-amino acids were efficiently racemised under mild conditions using various rhodium complexes as catalysts, e.g. [Rh(cod)Cl]2, in the presence of phosphines. (C) 2000 Elsevier Science Ltd.
- Hateley, Martin J.,Schichl, Daniel A.,Kreuzfeld, Hans-J?rn,Beller, Matthias
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- Kinetic study of stereochemical and other factors governing hydrolytic cleavage of a peptide ligand in binuclear palladium(II) complexes
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The dipeptide N-acetylmethionylglycine (MeCO-Met-Gly) reacted, via the thioether group in the methionyl side chain, with five different palladium(II) aqua complexes. The complexes cis-[Pd(en)(H2O)2]2+ (en = H2NCH2CH2NH2) and cis-[Pd(pn)(H2O)2]2+ (pn = H2NCH2CH2CH2NH2) yield [Pd2(μ-MeCO-Met-Gly)2(H2O)4] 4+ A, cis-[Pd(Met-S,N)(H2O)2]2+ yields trans-[Pd2(μ-MeCO-Met-Gly)2(H2O) 2(HMet)2]6+, B and trans-[Pd2{Cys(Me)-S,N}2(H2O)2] 4+ [Cys(Me) = S-methylcysteine] yields trans-[Pd2{μ-HCys(Me)}2(H2O) 2(MeCO-Met-Gly)2]6+ C. The complex cis-[Pd(dtco)(H2O)2]2+ (dtco = 1,5-dithiacyclooctane) yields [Pd2(μ-MeCO-Met-Gly)2(dtco)2]4+, D. These reactions and hydrolytic cleavage of the methionine-glycine amide bond in the co-ordinated MeCO-Met-Gly are conveniently monitored by 1H NMR spectroscopy. The rate of cleavage decreases in the order A > B ≈ C > D, in which the number of aqua ligands per peptide ligand decreases. Intramolecular attack by aqua ligands is more efficient than external attack by water molecules from the solvent. The peptide ligands occupying terminal and bridging positions in the binuclear palladium(II) complexes undergo hydrolysis at similar rates. This study shows the importance of polynuclear metal complexes in hydrolytic cleavage of peptide bonds.
- Chen, Xiaohua,Zhu, Longgen,Yan, Hong,You, Xiaozeng,Kostic, Nenad M.
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- Minisci-Type Alkylation of N-Heteroarenes by N-(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light
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A synthetic method that enables the Hantzsch ester-mediated Minisci-type C2-alkylation of quinolines, isoquinolines and pyridines by N-(acyloxy)phthalimide esters (NHPI) under blue LED (light emitting diode) light (456 nm) is described. Achieved under mild reaction conditions at room temperature, the metal-free synthetic protocol was shown to be applicable to primary, secondary and tertiary NHPIs to give the alkylated N-heterocyclic products in yields of 21–99%. On introducing a chiral phosphoric acid, an asymmetric version of the reaction was also realised and provided product enantiomeric excess (ee) values of 53–99%. The reaction mechanism was delineated to involve excitation of an electron-donor acceptor (EDA) complex, formed from weak electrostatic interactions between the Hantzsch ester and NHPI, which generates the posited radical species of the redox active ester that undergoes addition to the N-heterocycle.
- Kyne, Sara Helen,Li, Jiacheng,Siang Tan, Suan,Wai Hong Chan, Philip
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supporting information
(2022/01/11)
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- Methionine derivative and application thereof
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The invention relates to the technical field of chemical synthesis, and particularly discloses a methionine derivative and application thereof. The structure of the methionine derivative is shown as aformula (I). The methionine derivative provided by the invention is used as an oxidizing agent to be applied to an oxidation system, hydroxyl of a reaction substrate is oxidized into corresponding aldehyde or ketone, and no peculiar smell substance is generated in the reaction process; the yield of a target product is guaranteed, meanwhile, the reaction temperature can be effectively increased, the oxidation reaction can be normally conducted at the temperature higher than 0 DEG C, and the yield is high; and the methionine derivative can be recycled many times, the cost is saved, energy is saved, consumption is reduced, and the methionine derivative is environmentally friendly.
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Paragraph 0041-0049
(2020/12/06)
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- Synthesis method for organic synthesis of intermediate N-acetyl-DL-methionine
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The invention relates to a synthesis method for organic synthesis of an intermediate N-acetyl-DL-methionine. The method mainly includes the steps of: adding 3mol DL-methionine into 4-5mol 4-bromo-acetanilide for heating dissolution, adding 4-5mol bromoethylamine, conducting reflux for 90-120min, adding a 300ml ethanol solution, carrying out concentration and evaporation to dryness, lowering the temperature of the residue to 10-15DEG C, performing washing with a toluene solution, conducting washing with a nitroethane solution, conducting recrystallization in a butanol solution, and performing dehydration with a dehydrant, thus obtaining the finished product N-acetyl-DL-methionine.
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Paragraph 0006; 0014; 0015
(2018/07/30)
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- Reactivity of α-Amino Acids in the Reaction with Esters in Aqueous–1,4-Dioxane Media
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The kinetics of the reaction of a series of α-amino acids with 4-nitrophenyl acetate, 4-nitrophenyl benzoate, and 2,4,6-trinitrophenyl benzoate in aqueous 1,4-dioxane medium has been studied. Kinetics of the reactions involving 4-nitrophenyl acetate and 2,4,6-trinitrophenyl benzoate has complied with the Br?nsted dependence and revealed linear correlation between rate constant logarithm and the energy difference of the frontier orbitals of α-amino acids anions.
- Kochetova,Kustova,Kuritsyn
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- Separation and purification method for N-acetyl-D, L-methionine
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The invention discloses a separation and purification method for N-acetyl-D, L-methionine. The method comprises the steps of 1) subjecting an acetylation reagent and methionine salt to the acetylation reaction, adjusting the pH value of the reaction solution to be 3-5 by using an acidifying agent, maintaining the temperature of the reaction solution to be 50 DEG C-75 DEG C, and subjecting the reaction solution to the decoloration treatment; 2) adopting water as an eluent, subjecting the decolored reaction solution to the continuous chromatographic separation treatment through a continuous chromatographic separation system to respectively obtain an N-acetyl-D, L-methionine aqueous solution and a saline solution containing sodium acetate. The method enables the high-purity separation of N-acetyl-D, L-methionine, wherein the N-acetyl-D, L-methionine is completely and effectively separated from organic salts and inorganic salts. Therefore, the usage of organic solvents, toxic and harmful to the traditional production process, is avoided. Meanwhile, the method is low in energy consumption, high in production efficiency and simple in operation. The method improves the product yield and the product purity, which is green and environmentally-friendly.
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Paragraph 0037-0041
(2017/06/08)
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- A process for the preparation of L-methionine
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The invention aims to the field of chemical engineering, and relates to a method for preparing L-methionine. According to the method, acetylated saponification liquid is used as production raw material, acid is added into the raw material, the pH is adjusted to be acidic, after reduced pressure distillation, an organic solvent is used for treatment, so that a solution containing D,L-acetyl methionine is obtained, then the organic solvent is removed to obtain D,L-acetyl methionine crystals, and a resolution reaction is performed on the produced D,L-acetyl methionine crystals, so that the L-methionine is obtained; the technology does not need refined D,L-methionine, the soponification liquid for producing the D,L-methionine is used for performing an acetylated reaction, and therefore production cost is reduced; after the acetylation, water is evaporated to dryness, the organic solvent is used for desalting, the yield of the D,L-acetyl methionine reaches 97-99%, and the purity of the D,L-acetyl methionine reaches above 96%; the enzymolysis speed of the D,L-acetyl methionine is higher than that of a traditional method, the obtained L-methionine is good in crystal form and whiteness, the purity reaches above 99.5%, and the total yield of the L-methionine is improved to 78%; according to the technology, a circulation technology is integrated, the design is reasonable, and production cost is reduced.
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Paragraph 0052-0054
(2017/03/24)
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- Flavour Modifying Compounds
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A compound of formula (I) is used to modify the taste or flavour of a flavour composition or consumable product, wherein R1 is H, or a substituted, unsubstituted, branched or unbranched C1-C5 alkyl group and, NHR2 is a residue of an amino acid, is selected from Alanine (Ala), cysteine (Cys), Aspartic acid (Asp), phenylalanine (Phe), glutamic acid (Glu), histidine (His), isoleucine (Ile), lysine (Lys), leucine (Leu), methionine (Met), asparagines (Asn), glutamine (Gln), arginine (Arg), serine (Ser), theronine (Thr), valine (Val), tryptophan (Trp), tyrosine(Tyr) and Glycine (Gly), with the proviso that the compound is not N-acetyl glycine. Also disclosed are flavour compositions and consumable products containing such compounds.
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Page/Page column
(2014/05/20)
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- Studies on the biodegradation of fosfomycin: Synthesis of 13C-labeled intermediates, feeding experiments with rhizobium huakuii PMY1, and Isolation of Labeled Amino Acids from Cell Mass by HPLC
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Racemic (1R*,2R*)-1,2-dihydroxy-[1-13C 1]propylphosphonic acid and 1-hydroxy-[1-13C 1]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N-acetyl derivatives from the cell hydrolysate by reversed-phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly 13C-labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1.
- McGrath, John W.,Hammerschmidt, Friedrich,Kaehlig, Hanspeter,Wuggenig, Frank,Lamprecht, Guenther,Quinn, John P.
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experimental part
p. 13341 - 13348
(2012/03/22)
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- Regioselective synthesis of tetrasubstituted pyrroles by 1,3-dipolar cycloaddition and spontaneous decarboxylation
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We developed a novel regioselective synthesis of tetrasubstituted pyrroles via the classic 1,3-dipolar cycloaddition of α,β-unsaturated benzofuran-3(2H)-one and azlactones (1) followed by spontaneous decarboxylation. The complete regiochemical control of tetrasubstituted pyrroles was confirmed by the orthogonal synthesis of complementary regioisomers (7a and 7b) simply by using different azlactones (1a and 1b, respectively).
- Kim, Yongju,Kim, Jonghoon,Park, Seung Bum
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supporting information; experimental part
p. 17 - 20
(2009/08/07)
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- Palatability of aquaculture feed
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A method for enhancing the palatability of aquaculture food, the method comprising treating the food with a compound of Formula I: wherein R1, R2, R3, and n are as defined herein, are disclosed.
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- PROCESS FOR PREPARING AMINO ACIDS USING THE AMIDOCARBONYLATION REACTION
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The present invention relates to a sequence for the preparation of amino acids, for example alpha amino acids, in particular methionine, by making use of an amidocarbonylation reaction in the presence of a cobalt carbonyl catalyst and separating the catalyst in the form of a Co(N-amino acid)2 compound.
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Page/Page column 11-12
(2010/02/15)
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- PROCESS FOR PREPARING AMINO ACIDS USING THE AMIDOCARBONYLATION REACTION (1)
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The present invention relates to a sequence for the preparation of amino acids, for example alpha amino acids, in particular methionine, by making use of an amidocarbonylation reaction and reuse of the catalyst.
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Page/Page column 12
(2008/06/13)
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- Efficient chemoenzymatic synthesis of enantiomerically pure α-amino acids
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A general two-step chemoenzymatic synthesis for enantiomerically pure natural and nonnatural α-amino acids is presented. In the first step of the sequence, the ubiquitous educts aldehyde, amide and carbon monoxide react by palladium-catalyzed amidocarbonylation to afford the racemic N-acyl amino acids in excellent yields. In the second step, enzymatic enantioselective hydrolysis yields the free optically pure a-amino acid and the other enantiomer as the N-acyl derivative, both in optical purities of 85-99.5% ee. The advantage of the chemoenzymatic process compared to other amino acid synthesis are demonstrated by the preparation of various functionalized (-OR, -Cl, -F, -SR) α-amino acids on a 10-g scale.
- Beller, Matthias,Eckert, Markus,Geissler, Holger,Napierski, Bernd,Rebenstock, Heinz-Peter,Holla, E. Wolfgang
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p. 935 - 941
(2007/10/03)
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- Rhenium catalyzed sulfoxide reduction
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A mild, efficient method for the catalytic reduction of sulfoxides to sulfides with triphenylphosphine and the catalyst ReOCl3(PPh3)2 (I) is reported. Aryl sulfoxides are reduced faster than alkyl, and the reaction is successful for sterically hindered sulfoxides and those with common organic functional groups.
- Arterburn, Jeffrey B.,Perry, Marc C.
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p. 7941 - 7944
(2007/10/03)
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- Efficient Hg(II) Ion Transport through Liquid Membranes by Diamide Derivatives of Methionine with a 8-Quinolyl Group
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Several new diamide compounds with 8-quinolyl group were synthesized from methionine and their metal ion transport abilities as carriers through liquid membranes were investigated.Hg(II) ion was transported most effectively by these carriers.The selectivity for Hg(II) over Cu(II) was improved by the introduction of a bulky p-toloyl group as the acyl group on the 2-acylamino substituent.
- Kasuga, Kazuyuki,Hirose, Takuji,Takahashi, Toshikazu,Hiratani, Kazuhisa
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p. 2183 - 2186
(2007/10/02)
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- Functionalized DL-Amino Acid Derivatives. Potent New Agents for the Treatment of Epilepsy
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Structural analogues of the potent known anticonvulsant agent N-acetyl-DL-alanine N-benzylamide (1a) have been prepared (16 examples).The pharmacological activities of these products were evaluated in the maximal electroshock seizure (MES), the subcutaneous pentylenetetrazole seizure threshold (sc Met), and the rotorod (Tox) tests.The median effective doses (ED50) and the median toxic doses (TD50) for the most active compounds by both intraperitoneal and oral administration are reported.The most active compounds were N-acetyl-DL-phenylglycine N-benzylamide (1d) and N-acetyl-DL-alanine N-m-fluorobenzylamide (1m) along with the parent compound 1a.The ED50 values in the MES test for these three compounds compared well with phenobarbital, while their high TD50 values contributed to their large protective indexes, which approached that of phenytoin.When tested against four convulsant agents, compounds 1a and 1d displayed activity profiles significantly different from those reported for conventionally used antiepileptic drugs.
- Conley, Judith D.,Kohn, Harold
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p. 567 - 574
(2007/10/02)
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- THIOETHER PROTECTION VIA SELECTIVELY CLEAVABLE SULFONIUM SALTS
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There are few protecting groups available for the thioether functionality.The selective cleavage of 4-phthalimidobutyl- and p-methoxybenzylsulfonium salts make these derivatives ideal for thioether protection.
- Doi, Joyce Takahashi,Luehr, Gary W.
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p. 6143 - 6146
(2007/10/02)
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