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  • 1
    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.
    Additional Material: 2 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: 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.
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0009-2940
    Keywords: Host-guest complexes ; Molecular-dynamics (MD) simulation ; Enantioselective gas chromatography ; Cyclodextrins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energies of complexation of methyl (R)/(S)-2-chloropropionate [(R)/(S)-2] with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular-dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)-2 and the closest H-H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
    Additional Material: 9 Ill.
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  • 4
    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.
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  • 5
    ISSN: 0009-2940
    Keywords: Phosphines, optically active / Nickel complexes / Hydrogenation, enantioselective / Grignard cross coupling, enantinoselective / Gas chromatography, enantioselective ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric Catalysis, LI. - New Optically Active Chelating Phosphines - Synthesis and Application in Enantioselective CatalysisThe known triphosphines 1 and 4 were transformed into their monophosphine oxide and monophosphine sulfide derivatives 2, 3, 5, and 6 via NiCl2 complexes. 21 optically active phosphines were used as ligands in the Rh-catalysed hydrogenation of (Z)-α-acetamidocinnamic acid and itaconic acid as well as in the Ni-catalysed cross-coupling reaction of phenylethylmagnesium chloride with vinyl bromide. The optical inductions of the Grignard cross coupling reaction were determined the first time by enantioselective gas chromatography.
    Additional Material: 1 Ill.
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  • 6
    ISSN: 0009-2940
    Keywords: Azoles, optically active, thermolysis and photolysis of ; Walk rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanism of the Cyclopropane “Walk” Rearrangement: Synthesis and Properties of an Optically Active Diazoalkane-Toluene Adduct; a Highly Stereoselective N2 EliminationThe synthesis and the thermal and photochemical behavior of the optically active 2-diazo-1-methoxypropane-toluene adduct 3 are reported. The N2 elimination of 3 ocurs with one and the same stereochemical course upon thermolysis as well as direct photolysis: 7-(Methoxymethyl)-1,7-dimethyl-1,3,5-cycloheptatriene (1) is formed with retention of configuration at C-7 and 7-(methoxymethyl)-2,7-dimethyl-1,3,5-cycloheptatriene (2) with inversion of configuration at C-7. These stereochemical findings are explained by an intermediary singlet diradical 1[4] in which the ring closure between C-1 and C-7 or C-5 and C-7 is faster than the rotation around the single bond between C-6 and C-7. In the case of the thermally induced formation of 2 a concerted N2 elimination has to be considered as a competitive pathway. The results presented here are well in accord with the stereochemical analysis of the cyclopropane “walk” rearrangement 1⇋2 reported previously and are therefore a good evidence that the diradical intermediate 4 is also involved in the “walk” rearrangement. In the photochemically induced N2 elimination of 3, sensitized by benzophenone and leading again to 1 and 2, a surprisingly high degree of stereoselectivity is observed. Thus, the intermediary triplet diradical 3[4] must have a much shorter life time than ordinary 1,3-diradicals in the triplet state.
    Additional Material: 2 Ill.
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