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  • Chemistry  (99)
  • Inorganic Chemistry  (6)
  • Cyclodextrins  (2)
  • Dynamic gas chromatography  (2)
  • 11
    Electronic Resource
    Electronic Resource
    Synthesis and Absolute Configuration of the C12-Terpenoid Dehydrogeosmin from the Flower Scents of Rebutia marsoneri and Dolichothele sphaerica (Cactaceae); a new approach to bis-angularly substituted trans-decalins (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1949-1955 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optically pure(+)-(4S, 4aS, 8aS)-1,2,3,4,4a,5,8,8a-octahydro-4,8a-dimethylnaphthalen-4a-ol((+)-1; dehydrogeosmin) is released from flower heads of the two cactaceae Rebutia marsoneri and Dolichothele spharica. The absolute configuration of (+)-1 is identical with that of the known microbial metabolial geosmin (-)-2. The key reactions of the synthesis of 1 are the kinetically controlled transesterification of the primary alcohol 4 using a lipase from Candida cyclindracea and the stereo-and regiospecific angular alkylation of a cis-decalin skeleton by a Lewis-acid-assisted ring opening of the quaternary epoxy-alcohol 3 with MeMgBr/Cul. The sequence provides a new entry into the class of bis-angularly substituted trans-decalins.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760513
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  • 12
    Electronic Resource
    Electronic Resource
    Reaktionen von Aminosäuren und Peptiden, II. Darstellung von 2-Aminooxazolderivaten aus Peptidamiden mit Hexafluoracetanhydrid (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 973-985 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Amino Acids and Peptides, II. - Preparation of 2-Aminooxazole Derivatives from Peptide Amides with Hexafluoroacetic AnhydrideC-Terminal amino acid amide residues of peptide amides react with hexafluoroacetic anhydride to form stable 5-(trifluoroacetylamino)oxazole derivatives. Several representatives of this class of compounds have been synthesized and their structures determined by 1H-NMR and mass spectrometry and by their chemical reactions. The heterocyclization reaction can be used for the formation of volatile derivatives in the analysis of peptide amides on a microgram scale and for the identification of the C-terminal amino acid residue in peptide amides.
    Notes: C-Terminale Aminosäureamidreste von Peptidamiden reagieren mit Hexafluoracetanhydrid in guten Ausbeuten zu stabilen 5-(Trifluoracetylamino)oxazolderivaten. Verschiedene Vertreter dieser Verbindungen wurden dargestellt und ihre Struktur durch 1H-NMR-, Massenspektrometrie und chemische Reaktionen charakterisiert. Die Heterocyclisierungsreaktion kann im Mikrogramm-Maßstab zur Herstellung flüchtiger Derivate bei der Analytik von Peptidamiden und zur Identifizierung der C-terminalen Aminosäure von Peptidamiden benutzt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919790708
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  • 13
    Electronic Resource
    Electronic Resource
    Synthese der N-terminalen Aminosäure der Nikkomycine I, J, X und Z (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1615-1622 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820904
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  • 14
    Electronic Resource
    Electronic Resource
    Sequence and Conformation of Suzukacillin A (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1041-1062 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sequenz und Konformation von Suzukacillin ADie Sequenz des spannungsabhängige Membranporen bildenden Polypeptidantibiotikums Suzukacillin A wurde bestimmt durch eine Kombination von trifluoracetolytischer Spaltung, präparativer Isolierung von Fragmenten und Analyse durch Gaschromatographie - Massenspektrometrie sowie Felddesorptions- und Fast-Atom-Bombardment-Massenspektrometrie. Suzukacillin A ist ein mikroheterogenes Eikosapeptidantibiotikum (Ac-Aib-L-Ala-Aib-Ala-Aib-Ala(Aib)-Gln-Aib-Aib(Leu)-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Phl) mit einer Sequenz, einer α-helicalen Konformation (nach13C-NMR- und Circulardichroismus-Messungen) und membranmodifizierenden Eigenschaften, die dem Alamethicin ähnlich sind.
    Notes: The sequence of the potential-dependent membrane pore-forming polypeptide antibiotic suzukacillin A was determined by a combination of trifluoroacetolytic cleavage, preparative isolation of fragments, and analysis by gas chromatography - mass spectrometry, field-desorption and fast-atom bombardment mass spectrometry. Suzukacillin A is a microheterogeneous eicosapeptide antibiotic (Ac-Aib-L-Ala-Aib-Ala-Aib-Ala(Aib)-Gln-Aib-Aib(Leu)-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Phl) with a sequence, an α-helical conformation (according to 13C NMR and circular dichroism), and membrane-modifying properties related to alamethicin.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850518
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  • 15
    Electronic Resource
    Electronic Resource
    Synthese reiner Stereoisomerer der N-terminalen Aminosäure von Nikkomycin B (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 2165-2177 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519851107
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  • 16
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen, 182. Aufklärung der Struktur des Nucleosidantibiotikums Nikkomycin X (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 1494-1502 
    Details
    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, 182.  -  Structure Elucidation of the Nucleoside Antibiotic Nikkomycin XIn addition to the previously described nikkomycin Z, the structure of which could be confirmed, a new chitin synthase inhibiting component, nikkomycin X, could be isolated from the culture filtrate of Streptomyces tendae. Nikkomycin X is a structural isomer of nikkomycin Z and contains a 4-formyl-4-imidazolin-2-one unit instead of uracil. The structure was established by spectroscopic methods, chemical degradation and partial synthesis. Biological activity and antibiotic spectra of the two nikkomycins are similar.
    Notes: Neben dem bereits früher beschriebenen Nikkomycin Z, dessen Struktur bestätigt werden konnte, wurde aus dem Kulturfiltrat von Streptomyces tendae eine weitere die Chitinsynthase hemmende Komponente, Nikkomycin X, isoliert, die mit Nikkomycin Z strukturisomer ist, aber anstelle von Uracil 4-Formyl-4-imidazolin-2-on enthält. Die Struktur wurde mit spektroskopischen Methoden, durch chemischen Abbau und durch Teilsynthesen bewiesen. Die biologischen Aktivitäten und die Wirkungsspektren der beiden Nikkomycine sind ähnlich.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919791007
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  • 17
    Electronic Resource
    Electronic Resource
    Konfiguration von 2-Amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbuttersäure, der N-terminalen Aminosäure der Nikkomycine (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 1728-1735 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Configuration of 2-Amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbutyric Acid, the N-Terminal Amino Acid of the NikkomycinsThe N-ethylthio(thiocarbonyl)derivative 2 of the N-terminal amino acid 1 of the nikkomycin antibiotics shows a positive Cotton effect in its circular dichroism spectrum and therefore 1 is assigned to the L-series. The relative configuration of the C atoms 3 and 4 was ascertained by 1H-NMR investigations and crystal structure analysis. Accordingly, 1 is assigned the configuration 2S,3S,4S.
    Notes: Das N-Ethylthio(thiocarbonyl)derivat 2 der N-terminalen Aminosäure 1 der Nikkomycin-Antibiotika weist Circulardichroismus mit positivem Cottoneffekt auf und 1 ist daher der L-Reihe zu-zuordnen. Die relative Konfiguration an den C-Atomen 3 und 4 wurde durch 1H-NMR- und Kristallstrukturuntersuchungen bestimmt. Danach hat 1 die Konfiguration 2S,3S,4S.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019801112
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  • 18
    Electronic Resource
    Electronic Resource
    Reaktionen von Aminosäuren und Peptiden, IV. Synthese von Furanderivaten aus N-Methylaminosäuren (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1606-1609 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Amino Acids and Peptides, IV. - Synthesis of Furan Derivatives from N-Methyl Amino AcidsIn the reaction of N-methyl homophenylalanine and N-methyl norleucine with hexafluoroacetic anhydride the expected 1,3-oxazolidin-5-one derivatives are formed only as by-products. As main products 3-[methyl(trifluoroacetyl)amino]-2,5-bis(trifluoromethyl)furan derivatives could be isolated, the structures of which were identified by spectroscopic methods.
    Notes: Bei der Reaktion von N-Methylhomophenylalanin und N-Methylnorleucin mit Hexafluoracetanhydrid entstehen die erwarteten 1,3-Oxazolidin-5-on-Derivate nur als Nebenprodukte. Als Hauptprodukte konnten 3-[Methyl(trifluoracetyl)amino]-2,5-bis(trifluormethyl)furan-Derivate isoliert werden, deren Konstitutionen mit spektroskopischen Methoden ermittelt wurden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810910
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  • 19
    Electronic Resource
    Electronic Resource
    Die Struktur von Stenothricin - Korrektur eines früheren Strukturvorschlags (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1672-1684 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Structure of Stenothricin - Revision of a Previous Structure AssignmentA deviation from the previously assumed molecular mass was proved by fast-atom bombardment mass-spectrometry for the peptide antibiotic stenothricin. Recent investigations of a partial hydrolyzate revealed the presence of α-ketobutyrylvaline formed by hydrolysis of an α,β-dehydroaminobutyric acid (DH-Abu) moiety. Fragments obtained by partial hydrolysis of stenothricin after catalytic hydrogenation show that the previously identified tripeptide D-aThr-L-Ser-L-Dpr is linked over DH-Abu to the tetrapeptide L-Val-D-Ser-L-Lys-Sar. The carboxy group of Sar is esterified with the hydroxy group of D-aThr. The N-terminus is formed by D-cysteic acid, which is N-acylated by β-ketoacyl residues and is connected to the cyclic octapeptide lactone via the amino group of D-a Thr.
    Notes: Die durch Fast-Atom-Bombardment-Massenspektrometrie gegenüber früheren Annahmen nachgewiesene Abweichung der Molmasse von Stenothricin erforderte eine erneute Untersuchung dieses Peptidantibiotikums. Gegenüber früheren Befunden konnte im Partialhydrolysat zusätzlich α-Ketobutyrylvalin identifiziert werden, das durch Verseifung von α,β-Dehydroaminobuttersäure (DH-Abu) entsteht. Nach katalytischer Hydrierung von Stenothricin durch Partialhydrolyse erhaltene Fragmente zeigen, daß das schon früher identifizierte Tripeptid D-aThr-L-Ser-L-Dprüber DH-Abu an das Tetrapeptid L-Val-D-Ser-L-Lys-Sar gebunden ist. Die Carboxygruppe von Sar ist außerdem mit der Hydroxygruppe von D-aThr verestert. Die durch β-Ketoacylreste N-acylierte D-Cysteinsäure bildet den N-Terminus und ist über die Aminogruppe von D-aThr mit dem Octapeptidlacton verknüpft.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841007
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  • 20
    Electronic Resource
    Electronic Resource
    The C-Terminal Heptapeptides of Suzukacillin A and Alamethicin F30  -  Sequence, Conformation, and Synthesis (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 365-377 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die C-terminalen Heptapeptide von Suzukacillin A und Alamethicin F30  -  Sequenz, Konformation und SyntheseWährend der Sequenzierung des membranmodifizierenden Eikosapeptidantibiotikums Suzukacillin A wurden zwei C-terminale Heptapeptide durch selektive Trifluoracetolyse erhalten: L-Pro-L-Val-Aib-D-Iva-L-Gln-L-Phl und L-Pro-L-Val-Aib-Aib-L-Gln-L-Gln-L-Phl. Der chromatographische und spektroskopische Vergleich (FAB-MS, FD-MS, 13C-NMR, CD, UV) dieser isolierten natürlichen Fragmente mit dem synthetischen Segment L-Pro-L-Val-Aib-Aib-L-Gln-L-Gln-L-Phl (2) und dem synthetischen C-terminalen Segment von Alamethicin F30 L-Pro-L-Val-Aib-Aib-L-Glu-L-Gln-L-Phl (1) beweist die Sequenz 14-20 von Suzukacillin A.
    Notes: During the sequencing of the membrane-modifying eicosapeptide antibiotic suzukacillin A two C-terminal heptapeptides were obtained via selective trifluoroacetolysis: L-Pro-L-Val-Aib-D-Iva-L-Gln-L-Gln-L-Phl and -Pro-L-Val-Aib-Aib-L-Gln-L-Phl. The chromatographic and spectroscopic comparison (FAB MS, FD MS, 13C NMR, CD, UV) of these isolated natural fragments with the synthetic segment L-Pro-L-Val-Aib-Aib-L-Gln-L-Gln-L-Phl (2) and the synthetic C-terminal segment of alamethicin F30 L-Pro-L-Val-Aib-Aib-L-Glu-L-Gln-L-Phl (1) proved the sequence 14-20 of suzukacillin A.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850212
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