- Application of the thioacid-azide ligation (TAL) for the preparation of glycosylated and fluorescently labeled amino acids
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The reaction of thiocarboxylic acids with azides (thioacid-azide ligation, TAL) is a chemoselective transformation, leading to the formation of amide bonds. Especially in the case of electron-deficient sulfonyl azides, the reaction occurs in excellent yie
- Rohmer, Katja,Mannuthodikayil, Jamsad,Wittmann, Valentin
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- Synthesis of a Gln-Phe hydroxy-ethylene dipeptide isostere
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(Chemical Equation Presented) The protected Gln-Phe hydroxyethylene dipeptide isostere 1 was synthesized as a precursor for preparation of potential inhibitors of Botulinum neurotoxin B metalloprotease. The method allows for the synthesis of additional hydroxyethylene dipeptide isosteres such as 2 with functionalized P1 side chains. The isosteres prepared were coupled with a dipeptide to produce protected pseudotetrapeptide derivatives.
- Haug, Bengt Erik,Rich, Daniel H.
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p. 4783 - 4786
(2007/10/03)
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- Convenient synthesis of L-proline benzyl ester
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Mesylates or tosylates of δ-hydroxy-L-norvaline esters spontaneously afford L-proline esters upon exposure to aqueous buffer in near quantitative yield. This novel reaction has led to the development of a simple route to optically active proline esters.
- Cordova, Armando,Reed, Neal N.,Ashley, Jon A.,Janda, Kim D.
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p. 3119 - 3122
(2007/10/03)
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- Concise Synthesis of Enantiomerically Pure Phenylalanine, Homophenylalanine, and Bishomophenylalanine Derivatives Using Organozinc Chemistry: NMR Studies of Amino Acid-Derived Organozinc Reagents
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Protected phenylalanines 23 (seven examples), homophenylalanines 7 (eight examples), and bishomophenylalanines 8 (seven examples) have been prepared by palladium-catalyzed coupling of the amino acid-derived organozinc reagents 13, 5, and 6, respectively, with aryl iodides. While the reactions of the zinc reagent 13 may be conducted in both THF and DMF as solvent, the results obtained in DMF are generally superior. In the case of the reagents 5 and 6 the results are far superior in DMF. NMR investigations on the structure of the zinc reagents 13 in THF suggest that there is strong intramolecular coordination of the urethane carbonyl group, whereas in DMF this interaction is completely suppressed.
- Jackson, Richard F. W.,Moore, Rebecca J.,Dexter, Charles S.,Elliott, Jason,Mowbray, Charles E.
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p. 7875 - 7884
(2007/10/03)
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- Synthesis of the Major Component of Alamethicin
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Alamethicin (ALA), a natural membrane-active antibiotic, consists of several components.The major component, ALA I, was isolated in pure form and compared with the synthetic peptide acetyl-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phol obtained by stepwise segment condensation on a polystyrene support.The synthetic and natural products appeared essentially identical by amino acid analysis, high performance liquid chromatography, 600-MHz proton nuclear magnetic resonance spectroscopy, mass spectrometry, electrical activity in lipid bilayer membranes, and antimicrobial activity.It is concluded that ALA I has the structure indicated above.
- Gisin, B.F.,Davis, D.G.,Borowska, Z.K.,Hall, J.E.,Kobayashi, S.
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p. 6373 - 6377
(2007/10/02)
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