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  • 1995-1999  (2)
  • 1970-1974  (1)
  • 1
    Electronic Resource
    Electronic Resource
    An Efficient Synthetic Approach to Substituted Penta- and Hexahelicenes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3155-3163 
    Details
    ISSN: 1434-193X
    Keywords: Arenes ; Helical structures ; Cycloadditions ; NMR spectroscopy ; Semiempirical calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A two-step synthetic approach to penta- and hexahelicenes substituted at the terminal aromatic rings has been studied. This approach is based on the Diels-Alder reaction of 5,5′,8,8′-tetramethyl-3,3′,4,4′-tetrahydro-[1,1′]-binaphthalene (2b), 3-vinyl-1,2-dihydronaphthalene (5a), 5,8-dimethyl-3-vinyl-1,2-dihydronaphthalene (5b) and 3-vinyl-1,2-dihydrophenanthrene (15) followed by the aromatization of the cycloadducts. This method is flexible, efficient and of wide application to the synthesis of several benzenoid and nonbenzenoid penta- and hexahelicenes. The racemization energy barriers of helicenes 3, 9, 10, 13, 14, 17 and 18 were computed with the semiempirical quantum method AM1. The computed values show that, when methyl groups are introduced at the inner position of the terminal aromatic rings, the racemization barriers increase markedly. A structure analysis of the reaction products by 1H- and 13C-NMR spectroscopy is also presented.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Triglycidyl isocyanurate isomers (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 228 (1995), S. 25-40 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Triglycidylisocyanurat (TGIC) wurde aus dem Harzgemisch der Reaktionsprodukte von Cyanursäure und Epichlorhydrin durch Kristallisation aus Methanol getrennt. Die Fraktionen der Kristallisation wurden durch chemische Analyse, IR-Spektroskopie, hochaufgelöste 1H-NMR- und 13C-NMR-Spektroskopie, simultane thermische Analyse und DSC-Analyse getrennt charakterisiert. Die Struktur der beiden diastereomeren Racemate von TGIC (α- und β-TGIC) wurde mit Hilfe der hochaufgelösten NMR-Spektroskopie untersucht, und die Spektren wurden berechnet. Es wurde gefunden, daß die aus Methanol kristallisierte, hochschmelzende Fraktion (Schmelzpunkt: 156°C) dem β-diastereomeren Racemat von TGIC entspricht. Alle anderen aus Methanol kristallisierten Fraktionen (Schmelzpunkte im Bereich von 100-103°C) enthalten sowohl das α- als auch das β-diastereomere Racemat. Rekristallisieren aus Methanol liefert beide diastereomeren Racemate, was auf die Bildung von gemischten Kristallen hinweist.
    Notes: Triglycidyl isocyanurate (TGIC) was separated from the resinous reaction product of cyanuric acid and epichlorohydrin by crystallization from methanol. The crystallization fractions were separately characterized by means of functional group analysis, IR-spectroscopy, high-resolution 1H-NMR and 13C-NMR spectroscopy, simultaneous thermal analysis and DSC. The structure of the two diastereomer racemates of TGIC (β-TGIC and α-TGIC) was studied by using high-resolution NMR spectroscopy and the 1H-NMR spectra were calculated for both. It was found that the high-melting fraction (m. p. 156°C) which precipitated from the methanol-solution relates to the β-diastereomeric racemate of TGIC. All other methanol-soluble or slightly soluble fractions crystallized from the methanol solution (melting range 100-103°C) represent the α-diastereomer racemate of TGIC, with the β-diastereomer racemate always being present. Recrystallization from methanol always resulted in the presence of both diastereomers. This may indicate the presence of mixed crystals.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052280103
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  • 3
    Electronic Resource
    Electronic Resource
    Heterocyclische Verbindungen, II. Spektroskopische Konstitutions- und Konformations-bestimmung am 5-Äthyl-1-(3,4-dimethoxyphenyl)-7,8-dimethoxy-4-methyl-5H-2,3-benzodiazepin (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 3894-3903 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Compounds, II. 100-MHz-1 N.M.R., PFT-13 C N.M.R., and Mass-spectroscopic Studies of 1-(3,4-Dimethoxyphenyl)-5-ethyl-7,8-dimethoxy-4-methyl-5H-2,3-benzodiazepineThe structure and fine structure of the title compound 11) was elucidated by means of detailed n. m. r. and mass-spectroscopic studies. No enamine-(3H-2,3-benzodiazepine-) tautomer 2 can be detected, even at higher temperature, and the molecule has only two (boat-) conformations: 1a ⇌ 1b, of which 1a represents the lower-energy conformer; ΔG0 ≍ 1 kcal/mole.
    Notes: Auf Grund einer eingehenden NMR-und massenspektroskopischen Studie wird der Strukturbeweis für die Titelverbindung 11) erbracht. In 1 läßt sich das Enamin-(3H-2,3-Benzodiazepin-)-Tautomere 2 selbst bei erhöhter Temperatur nicht nachweisen. Es existieren nur konformere mit Wannenform 1a ⇌ 1b, von denen 1a die energieärmere ist; ΔG0 ≍ 1 kcal/mol.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741071220
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    Paper (German National Licenses)
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