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  • Inorganic Chemistry  (6)
  • Cyclodextrin derivatives  (5)
  • Cyclodextrins  (2)
  • Dynamic gas chromatography  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 262-272 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mass Spectrometry of Adenosine AnaloguesThe mass spectra of 23 trifluoroacetylated analogues of adenosine differing in the sugar moiety are investigated. The α- and β-anomers show characteristic intensity differences in the molecular ion and in the fragment ions m/e 310 and 424 (in pentose derivatives) as well as in m/e 550 and 680 (in hexose derivatives). The intensity differences can be explained by steric effects. The orientation of the hydroxyl groups does not influence the fragmentation process to such a degree that it is possible to draw systematic conclusions. For the identification of conformational isomers it is necessary to measure reference spectra. The ring size of the sugar is indicated by unique but low intensity fragments at m/e 524 and 410 (in furanosides of pentose derivatives), m/e 524 and 295 (in furanosides of hexose derivatives) as well as at m/e 508 and 433 (in pyranosides of hexose derivatives). Substitution at C-1' in hexose derivatives is indicated by ions at m/e 496 and 386.
    Notes: Die Massenspektren von 23 trifluoracetylierten Adenosin-Analoga (1-23), die sich in ihrem Zuckeranteil unterscheiden, weisen bei α- und β-Anomeren charakteristische Intensitätsunterschiede beim Molekül-Ion sowie bei den Fragment-Ionen m/e 310 und 424 (bei Pentose-Derivaten) bzw. m/e 550 und 680 (bei Hexose-Derivaten) auf. Die Intensitätsunterschiede lassen sich durch sterische Effekte erklären. Die Orientierung der Hydroxylgruppen beeinflußt die Fragmentierung nicht in dem Maße, daß eine systematische Zuordnung möglich ist. Für die Identifizierung der Konformationsisomeren ist die Aufnahme von Vergleichsspektren nötig. Die Ringgröße der Zucker ist durch das Auftreten von einzigartigen, allerdings wenig intensiven Fragment-Ionen bei m/e 524 und 410 (bei Furanosiden der Pentose-Derivate), m/e 524 und 295 (bei Furanosiden der Hexose-Derivate) und m/e 508 und 433 (bei Pyranosiden der Hexose-Derivate) erkennbar. Substitution an C-1' ist bei Hexose-Derivaten durch die Ionen m/e 496 und 386 gekennzeichnet.
    Additional Material: 5 Ill.
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  • 2
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metabolic Products of Microorganisms, 117. L-Arginyl-D-allo-threonyl-L-phenylalanine, an Amino Acid Antagonist from the Fungus Keratinophyton terreumAn antibiotically active tripeptide was isolated from laboratory cultures of the dermatophyte Keratinophyton terreum. Inhibitory effects have been observed on fungi (Paecilomyces varioti, Mucor miehei) but not on bacteria (Bacillus subtilis, Escherichia coll). The inhibition is antagonized by L-histidine and by L-threonine. The structure was elucidated by gas chromatographic and mass spectrometric investigations and was confirmed by comparison with synthetic L-arg-DL-allo-thr-L-phe. Synthetic L-arg-L-thr-L-phe does not show antifungal activity. Conditions for the fermentation and isolation of the antibiotic are reported.
    Notes: Aus Laboratoriumskulturen eines Dermatophyten wurde eine Substanz isoliert, die Pilze (Paecilomyces varioti, Mucor miehei), nicht aber Bakterien (Bacillus subtilis, Escherichia coli) hemmt. Die antibiotische Wirkung wird durch L-Histidin und L-Threonin aufgehoben. Die Struktur des Antibioticums wurde durch gaschromatographische und massenspektrometrische Untersuchungen als L-Argnyl-D-allo-threonyl-L-phenylalanin erkannt und durch Vergleich mit dem synthetischen Tripeptid L-Arginyl-DL-allo-threonyl-L-phenylalanin bestätigt. Synthetisches L-Arg-L-Thr-L-Phe ist antifungisch inaktiv. Bedingungen für Fermentation und Gewinnung des Antibioticums werden angegeben.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2221-2226 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metabolites of Microorganisms, 195. The Structure of Ophiocordin, an Antibiotic with Antifungal ActivityThe structure of the antibiotic Ophiocordin (9), which exhibits antifungal activity, was elucidated by chemical degradation, mass spectrometry, and NMR. Ophiocordin contains a novel 3-amino-hexahydro-4-hydroxyazepin system (5), which is esterified with 4-hydroxybenzoic acid and connected to 3,3′,5′-trihydroxy-2,4′-carbonylbis[benzoic acid] (7) via an amide bond between the 1-carboxy group and the amino group of the azepin system.
    Notes: Die Konstitution des antifungisch wirksamen Antibiotikums Ophiocordin (9) konnte durch chemischen Abbau, Massenspektrometrie und Kernresonanz aufgeklärt werden. Ophiocordin enthält ein neuartiges 3-Aminohexahydro-4-hydroxyazepin-System (5), an das 4-Hydroxybenzoesäure esterartig und 3,3′,5′-Trihydroxy-2,4′-carbonylbis[benzoesäure] (7) über die Carboxylgruppe in 1-Stellung säureamidartig gebunden ist.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 328-332 
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Terpenoid hydrocarbons ; Chiral carbonyl compounds ; Flavor alcohols ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modified cyclodextrins interact enantioselectively with a great variety of volatile chiral constituents of essential oils by forming diastereomeric inclusion complexes. Capillary gas chromatography is used for resolving the enantiomers of terpenoid hydrocarbons (camphene, α-pinene, limonene, α-phellandrene), carbonyl compounds (carvone, fenchone, menthone, isomenthone, piperitone, camphor, myrtenal), and alcohols (trifluoroacetylated β-citronellol, myrtenol, trans-pinocarveol, 1-octen-3-ol, and underivatized linalool). The enantiomeric composition of some of these compounds in a variety of essential oils is investigated.
    Additional Material: 9 Ill.
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  • 5
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Polychlorinated pesticides ; Polychlorinated biphenyls (PCBs) ; Pyrethroid insecticides/Allethrin ; Organophosphorus pesticides/Acephate, Malaoxon ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of the polychlorinated polycyclic xenobiotics heptachlor, cis- and trans-chlordane, cis- and trans-heptachlorepoxide, oxychlordane, and bromocyclen have been resolved by gas chromatography with selectively substituted cyclodextrins. The order of elution of these compounds and of α-hexachlorocyclohexane (α-HCH) was determined by comparison with enantiomerically enriched reference compounds obtained by preparative enantioselective gas chromatography.A separation of the eight stereoisomers of the pyrethroid insecticide allethrin into seven peaks was achieved. Both trans-diastereomers were separated into their enantiomers and the order of elution could be determined by comparison with commercially available (S)-bioallethrin and trans-bioallethrin. Also one cis-diastereomer was separated, wheras the other cis-isomer could not be resolved. In addition 15 out of 19 stable atropisomeric polychlorinated biphenyls with 5, 6 and 7 chlorine substituents, some chiral organophosphorus pesticides, including acephate and malaoxon and the herbicide bromoacil were separated.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 257-260 
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; Diterpene Hydrocarbons ; Cyclodextrin derivatives ; Essential oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomeric diterpene hydrocarbons were isolated from different plants and identified by mass spectrometric and NMR investigations. All enantiomeric pairs could be resolved by capillary gas chromatography using either heptakis(2,6-di-O-methyl-3-O-pen-tyl)-β-cyclodextrin or heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin as chiral stationary phases.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 376-378 
    ISSN: 0935-6304
    Keywords: Resolution of atropisomers ; Alkylated biphenyls ; Polychlorinated biphenyls (PCBs) ; Dynamic gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectively alkylated cyclodextrins have been used to resolve the enantiomers of 2,2′ alkylated biphenyls. The configurational stability of 2,2′-dimethyl and 2,2′-diethyl biphenyls is insufficient for gas chromatographic separation even at ambient temperature. 2-Isopropyl-2′-t-butyl- and 2,2′-di-t-butylbiphenyl are configurationally stable under the conditions applied, whereas 2,2′-diisopropyl- and 2,2′-bis(trifluoromethyl)biphenyl show temperature-dependent interconversion of the enantiomers during chromatography. The gas chromatographic separation of the enantiomers of some ortho trichlorinated biphenyls carrying 4, 5, and 6 chlorine substituents has been demonstrated for the first time.
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  • 8
    ISSN: 0935-6304
    Keywords: Enantioselective capillary gas chromatography ; Cyclodextrins ; Inverse substitution pattern ; Mechanism of chiral recognition ; Applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transferring the site of specific substitution of dipentylated cyclodextrins with methyl or acyl residues from the secondary 3-hydroxyl group to the primary 6-hydroxyl group was expected to provide new information on the mechanism of chiral recognition. The 3-position points towards and the 6-position points away from the cyclodextrin cavity which via inclusion complex formation is supposed to play a major role in chiral separation. The “inverse” 6-O-acyl-2,3-di-O-pentyl-cyclodextrins displayed almost no enantioselectivity but the corresponding 6-O-methyl derivatives are a versatile supplement to the chiral capillary GC phases nowadays available. Among the compounds that could be enantiomerically resolved are alcohols, amino acids, alkyl halides, bicyclic ethers, acetals, olefins, other hydrocarbons and chiral pharmaceuticals.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 184-189 
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Monoterpene hydrocarbons ; Essential oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a dual column gas chromatograph equipped with two capillary columns coated with heptakis(6-O-methyl-2,3-di-O-pentyl)-β-cyclodextrin (6-me-2,3-pe-β-CD) and octakis(6-O-methyl-2,3-di-O-pentyl)-γ-cyclodextrin (6-me-2,3-pe-γ-CD), respectively, all important olefinic monoterpene hydrocarbons occurring in essential oils, including α-thujene, α- and β-pinene, camphene, sabinene, α- and β-phellandrene, Δ-3-carene and limonene can be resolved into enantiomers. With the chromatographic system described the characteristic enantiomeric composition of these monoterpene hydrocarbons in essential oils can be determined.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; Sesquiterpene hydrocarbons ; Cyclodextrin derivatives ; Essential oils ; Liverworts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of sesquiterpene hydrocarbons commonly occurring in essential oils has been prepared as racemic mixtures by chemical synthesis. Preparative gas chromatography with selectively per-O-alkylated cyclodextrins has been employed for the isolation of enantiomeric mixtures or pure enantiomers from the essential oils of higher plants and liverworts (Hepaticae). The enantiomers of α-curcumene, α- and β-bisabolene, β-elemene, δ-elemene, α-copaene, δ-cadinene, cis- and trans-calamenene, and bicyclogermacrene could be resolved by enantioselective gas chromatography on capillary columns coated with cyclodextrin derivatives. The enantiomeric composition of these sesquiterpene hydrocarbons in various essential oils was determined.
    Additional Material: 7 Ill.
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