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  • 1
    ISSN: 0947-3440
    Keywords: Peptaibol ; Zervamicin ; Synthesis ; Aib ; Fmoc ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isotopically labelled C-terminal fragment of zervamicin, H-Hyp10-[4,4-2H2-Gln]-Aib-Hyp-Aib-Pro-Phl16, has been synthesized in solution by a Fmoc/tert-butyl strategy in 28% overall yield. The Fmoc group was removed by reaction for 2 min with 0.1 M NaOH in dioxane/methanol/water, (30:9:1, v:v:v). The couplings of the sterically hindered Aib residues were achieved by means of either BOP/DMAP activation or Fmoc-Aib-Cl. Acid deprotection of the peptide was performed by reaction with 50% TFA in CH2Cl2 for 30 min without significant cleavage of the acid-labile Aib-Pro and Aib-Hyp peptide bonds.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 3 (1997), S. 193-208 
    ISSN: 1075-2617
    Keywords: peptaibol ; antibiotic ; peptide synthesis ; NMR spectroscopy ; mass spectrometry ; isotope labelling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the first time the total synthesis of the peptaibol antibiotic zervamicin IIB is described. Synthesis of this peptaibol was achieved by the Fmoc/tert-butyl strategy in solution using a fragment condensation approach. Three fragments of zervamicin IIB were obtained by stepwise elongation with Fmoc amino acids using BOP as a coupling reagent. For the introduction of the highly sterically hindered α-aminoisobutyric acid residues BOP/DMAP activation was applied. The Fmoc group was removed by reaction with 0.1 M NaOH in dioxane/methanol/water (30/9/1, v/v/v). Peptide fragments were coupled by means of a new coupling reagent, CF3-PyBOP. Using the strategy developed, zervamicin IIB and two analogues specifically deuterium-labelled at different positions of the glutamine-11 residue have been synthesized in 40% overall yield based on the isotopically labelled amino acid and with 98±2% of isotope enrichment. FAB mass spectroscopy, 600 MHz 1H-NMR spectroscopy and high-performance liquid chromatography provided convincing evidence that the synthetic products, zervamicin IIB and its deuterium-labelled analogues, fully correspond to the naturally occurring zervamicin IIB. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 857-859 
    ISSN: 1434-193X
    Keywords: α,α-Dialkylated amino acids ; Isotopic labeling ; Strecker synthesis ; Solvent effects ; Stereoselective hydrolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---[15N]-D-isovaline was prepared from DL-[α-15N]-α-aminoisovaleramide by enzymatic resolution with Mycobacterium neoaurum. The 15N-isotope was introduced during the Strecker synthesis of its precursor, e.g. aminoisovaleronitrile. Attempts to prepare the amino nitrile precursor of [15N]-α-aminoisobutyric acid (Aib) led to a poor yield and loss of the label. Significantly, improved results were obtained when a cosolvent is present during formation of aminoisobutyronitrile.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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