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  • Inorganic Chemistry  (6)
  • capillary zone electrophoresis  (2)
  • 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Andrena wilkella male bees discriminate between enantiomers of cephalic secretion components (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 429-441 
    Details
    ISSN: 1573-1561
    Keywords: Enantiomer discrimination ; male patrolling ; odor marking ; Hymenoptera ; Apoidea ; Andrena wilkella ; bee ; EAG ; spiroacetal ; absolute configuration ; 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee,Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior inA. wilkella.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021775
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  • 2
    Electronic Resource
    Electronic Resource
    New technique for the determination of interconversion processes based on capillary zone electrophoresis: Studies with axially chiral biphenyls (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 441-445 
    Details
    ISSN: 0899-0042
    Keywords: capillary zone electrophoresis ; axially chiral biphenyls ; energy barrier ; cyclodextrin derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new technique is presented for the investigation of the rotational energy barrier of axially chiral biphenyls, based on capillary zone electrophoresis using cyclodextrin derivatives as chiral selectors. Only minute amounts are required for the investigation of dynamic processes with energy barriers of 100-130 kJ/mol. The influence of the chiral selector on the conformational stability of atropisomers can be determined separately for each enantiomer. Additionally, segmentation of the capillary into different buffer zones allows us to exclude any influence of the chiral selector on the rotational energy barrier. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Massenspektrometrische Untersuchung von Analogen des Adenosins (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 262-272 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050128
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  • 4
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen, 117. L-Arginyl-D-allo-threonyl-L-phenylalanin, ein Aminosäure-Antagonist aus dem Pilz Keratinophyton terreum (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 816-825 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060311
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  • 5
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen, 195. Konstitution von Ophiocordin, einem Antibiotikum mit antifungischen Eigenschaften (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2221-2226 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130617
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  • 6
    Electronic Resource
    Electronic Resource
    Neue optisch aktive Chelat-Phosphane - Synthese und Verwendung in der enantioselektive Katalyse (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 847-853 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230433
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  • 7
    Electronic Resource
    Electronic Resource
    Zum Mechanismus der Cyclopropan-“Walk”-Umlagerung: Synthese und Eigenschaften eines optisch aktiven Diazoalkan-Addukts von Toluol; eine hochstereoselektive N2-EliminierungHerrn Professor Horst Prinzbach zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 197-208 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250132
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  • 8
    Electronic Resource
    Electronic Resource
    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 119-126 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270120
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  • 9
    Electronic Resource
    Electronic Resource
    A New Application of Capillary Zone Electrophoresis: Determination of Energy Barriers of Configurationally Labile Chiral CompoundsC. W. thanks the Fonds der Chemischen Industrie for a scholarship. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 1635-1636 
    Details
    ISSN: 0570-0833
    Keywords: atropisomerism ; biphenyls ; capillary zone electrophoresis ; chirality ; cyclodextrins ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199516351
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