- A Versatile Boc Solid Phase Synthesis of Daptomycin and Analogues Using Site Specific, On-Resin Ozonolysis to Install the Kynurenine Residue
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A de novo solid-phase synthesis of the cyclic lipodepsipeptide daptomycin via Boc chemistry was achieved. The challenging ester bond formation between the nonproteinogenic amino acid kynurenine was achieved by esterification of a threonine residue with a
- Xu, Buzhe,Hermant, Yann,Yang, Sung-Hyun,Harris, Paul W. R.,Brimble, Margaret A.
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- Chemoenzymatic synthesis of glutamic acid analogues: Substrate specificity and synthetic applications of branched chain aminotransferase from Escherichia coli
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(Chemical Equation Presented) A new route to α-keto acids is described, based on the ozonolysis of enol acetates obtained from α-substituted β-keto esters. Escherichia coli branched chain aminotransferase (BCAT) activity toward a variety of substituted 2-oxoglutaric acids was demonstrated analytically. BCAT was shown to have a broad substrate spectrum, complementary to that of aspartate aminotransferase, and to offer access to a variety of glutamic acid analogues. The usefulness of BCAT was demonstrated through the synthesis of several 3- and 4-substituted derivatives.
- Xian, Mo,Alaux, Sebastien,Sagot, Emmanuelle,Gefflaut, Thierry
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p. 7560 - 7566
(2008/03/11)
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- A concise synthesis of (2S,4R)- and (2S,4S)-4-methylglutamic acid
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A concise, multi-gram scale method for producing the bioactive and enantiomerically pure epimers, (2S,4R)- and (2S,4S)-glutamic acids, in a single synthetic scheme is described.
- Gu, Zi-Qiang,Li, Min
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p. 3203 - 3205
(2007/10/03)
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- 2,8'-Disubstituted-1,1'-Binaphthyls: A New Pattern in Chiral Ligands
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The title binaphthyls 19 and 26, which are the positional isomers of 2-methoxy-2'-(diphenylphosphino)-1,1'-binaphthyl (MOP, 19) and 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN, 26), have been synthesized by Suzuki coupling as the key step (10 + 15 -> 18), followed by functional group transformations, involving C-P and C-N bond formation (18 -> 19 and 18 -> 23). Racemic intermediate 22 was resolved by cocrystallization with N-benzylcinchonidinium chloride and the absolute configuration determined by X-ray crystallography. These novel binaphthyls are configurationally stable and, as such, potentially usable as chiral ligands in asymmetric reactions. Michael addition of the glycine-derived enolate 40 to methyl acrylate, carried out in the presence of (R)-(-)-27 as the chiral phase-transfer catalyst, afforded L-glutamic acid (S)-(+)-43 of 92% ee (after hydrolysis of the primary product).
- Vyskocil, Stepan,Meca, Ludek,Tislerova, Iva,Cisarova, Ivana,Polasek, Miroslav,Harutyunyan, Syuzanna R.,Belokon, Yuri N.,Stead, Russel M. J.,Farrugia, Louis,Lockhart, Stephen C.,Mitchell, William L.,Kocovsky, Pavel
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p. 4633 - 4648
(2007/10/03)
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- Synthesis of 4,4-Disubstituted L-Glutamic Acids by Enzymatic Transamination
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The syntheses of optically pure 4,4-dimethyl-L-glutamic acid as well as (2S,4R)- and (2S,4S)-4-hydroxy-4-methylglutamic acids have been achieved by transamination of the corresponding 2-oxo-4,4-dimethyl- and rac-2-oxo-4-hydroxy-4-methylglutaric acids using glutamic oxalacetic transaminase (GOT).
- Helaine, Virgil,Rossi, Joel,Gefflaut, Thierry,Alaux, Sebastien,Bolte, Jean
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p. 692 - 697
(2007/10/03)
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- Chemoenzymatic synthesis of (4S)- and (4R)-4-methyl-2-oxoglutaric acids, precursors of glutamic acid analogues
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Alkylation of dimethyl 2,2-dimethoxyglutarate followed by enzymatic resolution afforded (4S)- and (4R)-4-methyl-2-oxoglutaric acid in an enantiomerically pure form. The activity of glutamic oxalacetic transaminase towards these compounds has been measured. Their enzymatic transamination provides an efficient synthesis of (4S)- and (4R)-4-methyl-L-glutamic acids which are very useful for characterisation of glutamate receptors in the central nervous system.
- Helaine, Virgil,Bolte, Jean
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p. 3403 - 3406
(2007/10/03)
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- A convenient and efficient synthesis of (2S,4R)- and (2S,4S)-4-methylglutamic acid
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Both enantiomerically pure (2S,4S)- and (2S,4R)-4-methylglutamic acids have been prepared in an overall 60% yield, by a convenient 7-step synthesis based on C-4 alkylation/epimerization of readily available (S)-pyroglutamic acid.
- Coudert, Elisabeth,Acher, Francine,Azerad, Robert
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p. 863 - 865
(2007/10/03)
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- Resolution and regioselective protection of glutamic acid analogues. I- Resolution of diastereomeric α-boroxazolidone derivatives
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Diastereomeric α-boroxazolidone γ-phenylethylamide (or γ-phenylethanolamide) derivatives of 2-, 3- or 4-substituted glutamic acid analogues have been separated by silicagel chromatography, resulting, after deprotection, in a practical method for the resolution of most of these unnatural amino acids.
- Acher,Azerad
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p. 731 - 744
(2007/10/02)
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- Enzymatic Synthesis of 4-Methyl- and 4-Ethyl-L-glutamic Acids
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This paper reports the activity of glutamic oxalacetic aminotransferase (GOT) from pig heart and bacteria for racemic 4-hydroxy-, 4-methyl-, and 4-ethyl-2-ketoglutaric acids.These compounds are good substrates for GOT with Vmax values of, respectively, 70, 90, and 130 percent relative to the natural substrate, 2-ketoglutaric acid.GOT displays high enantioselectivity toward 4-methyl-2-ketoglutaric acid and 4-ethyl-2-ketoglutaric acid; the synthesis of both diastereoisomers of the corresponding 4-substituted L-glutamic acids is thus possible.
- Echalier, Frederique,Constant, Olivier,Bolte, Jean
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p. 2747 - 2750
(2007/10/02)
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- Synthesis of Enantio- and Diastereo-isomerically Pure β- and γ-Substituted Glutamic Acids via Glycine Condensation with Activated Olefins
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The glycine fragment in the nickel(II) complex formed from the Schiff base of glycine and (S)-o-benzophenone undergoes base-catalysed Michael addition in methanol in the presence of MeONa to the activated olefins methyl acrylate, acrylonitrile, methyl methacrylate, acrolein, and methyl trans-cinnamate.Complexes of substituted (S)-glutamic acid or its derivatives were formed in good chemical yields with almost complete diastereoselection at the α-carbon atom of the amino acid moiety.Diastereoselection at the β- and γ-atoms was not significant, but the isomeric complexes could be easily separated chromatogrphically.Cleavage of the pure diastereoisomers with aqueous HCl gave, in good yields, optically pure glutamic acids and regenerated the original chiral reagent.The configurations of the amino acid β- and γ-carbon atoms were determined by 1H n. m. r. spectroscopy and crystal structure X-ray analysis of the corresponding original complexes.The addition to acrolein, catalysed by triethylamine in methanol, leads to the 1,4-adduct exclusively.The amino acid thus obtained could be converted into (S)-proline by reduction with NaBH4.
- Belokon, Yuri N.,Bulychev, Aleksandr G.,Ryzhov, Mikhail G.,Vitt, Sergei V.,Batsanov, Andrei S.,et al.
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p. 1865 - 1872
(2007/10/02)
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- The Synthsis of (+)-Marmelo Lactones A and B and the Assignment of the Absolute Configurations of Marmelo Lactones
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(+)-Marmelo Lactones A (VA) and B (VB) were synthesized from erythro-γ-methyl-L-glutamic acid (IA) and threo acid (IB), respectively.The absolute configurations of natural marmelo lactones were thus determined to be (2R,4S) for (+)-marmelo lactone A and (
- Nishida, Yoshihiro,Ohrui, Hiroshi,Meguro, Hiroshi
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p. 1211 - 1216
(2007/10/02)
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- Resolution of γ-Methyl and γ-Fluoroglutamic Acids. Lack of Stereospecificity of Leucine Aminopeptidase with L-Leucyl-L-erythro-γ-substituted Glutamates
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The hydrolysis of L-leucyl-γ-substituted D,L-glutamates by leucine aminopeptidase, from porcine kidney, is stereospecific with threo-γ-methyl and threo-γ-fluoroglutamate containing dipeptides whereas there is a lack of stereospecificity with erythro-isomers.The optical purities of L-threo- and L-erythro-glutamate isomers thus obtained have been monitored by gas chromatography, high pressure liquid chromatography, or nuclear magnetic resonance.The optical rotations of optically pure L-isomers have been measured and the discrepancies with former publications are discussed.
- Bory, Sonia,Dubois, Joelle,Gaudry, Michel,Marquet, Andree,Lacombe, Liliane,Weinstein, Shulamith
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p. 475 - 480
(2007/10/02)
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