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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1615-1622 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the N-Terminal Amino Acid of the Nikkomycins I, J, X, and ZA mixture of four stereoisomers of 2-amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbutanoic acid (14), the N-terminal amino acid of the nikkomycin antibiotics could be synthesized in a twelve-step procedure. By comparison of 1H NMR spectra, mass spectra and of the gas chromato-graphic behaviour of various derivatives the constitution and relative configuration of the natural compound has been confirmed.
    Notes: Ein Gemisch aus vier Stereoisomeren von 2-Amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbuttersäure (14) der N-terminalen Aminosäure der Nikkomycin-Antibiotika konnte in einer zwölfstufigen Synthese dargestellt werden. Durch Vergleich der 1H-NMR-Spektren, Massenspektren und des gaschromatographischen Verhaltens verschiedener Derivate von Synthese- und Naturprodukt wird die Richtigkeit der angenommenen Konstitution und relativen Konfiguration bestätigt.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 2165-2177 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Pure Stereoisomers of the N-terminal Amino Acid of Nikkomycin BPure stereoisomers of 2-amino-4-hydroxy-4-(p-hydroxyphenyl)-3-methylbutanoic acid (8c), the N-terminal amino acid of nikkomycin B (10a, b), were synthesized by 1,3-dipolar cycloaddition of (ethoxycarbonyl)methanenitrile oxide (2) to the olefines 1, separation of the diastereomeric 4,5-dihydro-3-isoxazolecarboxamides 6, and diastereoselective reductive cleavage and hydrolysis of 6. X-ray structure analysis revealed the absolute configuration (2R,3R,4R) for one pure synthetic stereoisomer of 8c. Gas chromatography on a chiral stationary phase and 1H NMR enabled us to assign the (2S,3S,4S) configuration to the natural amino acid.
    Notes: Reine Stereoisomere von 2-Amino-4-hydroxy-4-(p-hydroxyphenyl)-3-methylbuttersäure (8c), der N-terminalen Aminosäure von Nikkomycin B (10a, b), wurden nach 1,3-dipolarer Cycloaddition von (Ethoxycarbonyl)methannitriloxid (2) an die Olefine 1 und Trennung der diastereomeren 4,5-Dihydro-3-isoxazolcarboxamide 6 durch diastereoselektive reduktive Spaltung und Verseifung von 6 hergestellt. Mit Hilfe eines reinen, synthetischen Stereoisomers von 8c, dessen absolute Konfiguration (2R,3R,4R) durch Kristallstrukturanalyse bestimmt werden konnte, sowie mit Hilfe von Gaschromatographie an chiraler Phase und 1H-NMR gelang es, der natürlichen Aminosäure die Konfiguration (2S,3S,4S) zuzuordnen.
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Three Novel Amino Acids from the Nikkomycin Complex - Structure Elucidation and SynthesisFrom the culture medium of Streptomyces tendae Tue 901 some new metabolites were characterized: 2-amino-4-hydroxy-3-methyl-4-(2-pyridyl)butanoic acid (1) [nikkomycin E], its isomer 2-amino-4-hydroxy-3-methyl-4-(3-pyridyl)butanoic acid (2) [as N-terminal constituent of the nikkomycins Px (5) and Rz (6)], and 2-amino-4-hydroxy-4-(2-pyridyl)butanoic acid (3) [as N-terminal amino acid of the nikkomycins Kx (7) and Kz (8)]. The structure elucidation was achieved by NMR, mass spectrometry and by comparison with synthetic reference compounds.
    Notes: Aus dem Kulturfiltrat von Streptomyces tendae Tue 901 wurden weitere neue Metabolite charakterisiert: 2-Amino-4-hydroxy-3-methyl-4-(2-pyridyl)buttersäure (1) [Nikkomycin E], die dazu isomere 2-Amino-4-hydroxy-3-methyl-4-(3-pyridyl)buttersäure (2) [als N-terminaler Baustein der Nikkomycine Px (5) und Rz (6)] und 2-Amino-4-hydroxy-4-(2-pyridyl)buttersäure (3) [als N-terminale Aminosäure der Nikkomycine Kx (7) und Kz (8)]. Die Strukturaufklärung erfolgte durch Kernresonanz, Massenspektrometrie und durch Vergleich mit entsprechenden Syntheseprodukten.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metabolites of Microorganisms, 1891)  -  Structure Elucidation and Partial Synthesis of the Nucleoside Antibiotic Nikkomycin BIn the culture filtrate of Streptomyces tendae, from which the nucleoside antibiotics nikkomycin Z2) (1a) and nikkomycin X3) (1b) were isolated, a third component, nikkomycin B (7), was found. This new antibiotic contains a p-hydroxyphenyl residue instead of a 3-hydroxypyridyl residue in the amino acid moiety (6). The amino acid is linked to a 5-amino hexuronic acid to which 4-formyl-4-imidazolin-2-one is bound as an N-glycoside. The structure of the new amino acid constituent could be derived by mass spectrometry and was confirmed by synthesis of a mixture of diastereomers of 2-amino-4-hydroxy-4-(p-hydroxyphenyl)-3-methylbutyric acid.
    Notes: Das Kulturfiltrat von Streptomyces tendae, aus dem die Nucleosidantibiotika Nikkomycin Z2) (1a) und Nikkomycin X3) (1b) isoliert werden konnten, lieferte noch Nikkomycin B (7), das an-stelle des 3-Hydroxypyridin-Systems von 1 einen p-Hydroxyphenyl-Rest im Aminosäurebaustein 6 enthält. Dieser ist peptidartig mit einer 5-Aminohexuronsäure verknüpft, an die 4-Formyl-4-imidazolin-2-on N-glykosidisch gebunden ist. Die Ableitung der Konstitution des neuen Aminosäurebausteins gelang durch Massenspektrometrie und Synthese eines Diastereomerengemisches der 2-Amino-4-hydroxy-4-(p-hydroxyphenyl)-3-methylbuttersäure (6). In der biologischen Aktivität ist Nikkomycin B von den genannten Vertretern dieser Gruppe nicht zu unterscheiden.
    Additional Material: 1 Ill.
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