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  • 1
    ISSN: 1434-4475
    Keywords: Chiroptical properties ; Coumarins ; Farnesiferol A and isomers ; 1H-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es werden die CD-Spektren von 16 natürlich vorkommenden Sesquiterpen-Umbelliferon-Ethern, einschließlich Farnesiferol A mit allen Isomeren und allen Acetyl- bzw. 6-Oxo-Derivaten, im signifikanten Wellenlängenbereich von 350–200 nm beschrieben. Elf der Verbindungen wurden aus einem „Asa Foetida“-Präparat isoliert, fünf weitere bereits als Naturstoffe bekannte Derivate wurden mittels Acetylierung oderJones-Oxidation synthetisiert. Zusätzlich konnte eine neue Verbindung —Kamolonol (14) — isoliert werden, dessen Struktur durch zweifache Methylgruppenwanderung im Drimenyl-Sesquiterpenanteil charakterisiert ist. Die Strukturemittlung erfolgte mittels spektroskopischer Methoden (1H-NMR, MS, IR, UV und CD).
    Notes: Abstract The CD spectra of 16 naturally occurring sesquiterpene-umbelliferone ethers, including the complete set of farnesiferol A isomers with all acetates and 6-oxoderivatives, are reported over the significant wavelength range of 350–200 nm. 11 compounds were isolated from an “Asa Foetida” sample and 5 further derivatives, already known as natural products, were obtained by acetylation orJones oxidation. In addition, a new compound — kamolonol (14) — was isolated. Its structure is characterized by twofold methyl migration in the drimenol derived sesquiterpene moiety.1H-NMR, MS, IR, UV, and CD data of the new compound are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 124 (1993), S. 185-198 
    ISSN: 1434-4475
    Keywords: Vitamin D ; Force-field calculations ; LIS-simulation ; NOE-measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die konformationelle Beweglichkeit von Vitamin D wurde mittels einer Kombination aus Kraftfeld Rechnungen, LIS-Messungen und LIS-Rechnungen untersucht. Neben den beiden A-Ring Sesselformen wurden auch A-Ring Twistformen aufgefunden. Die Ursache für das Vorhandensein von diesen Twistformen liegt in sterischen Wechselwirkungen, verursacht durch das Substitutionsmuster des A-Ringes in diesem seco-Steroid.
    Notes: Abstract The conformational flexibility of vitamin D was investigated by a combination of force field calculations, LIS measurements and LIS simulations. Besides the two A-ring chair forms, A-ring twist forms were detected and were attributed to steric interactions arising from the substitution pattern of this class of seco-steroids.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 595-600 
    ISSN: 0170-2041
    Keywords: Vitamin D ; Isoxazolines ; Cholecalciferol derivatives ; Ergocalciferol derivatives ; Calciferol derivatives ; Calculations, force-field ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Conformation and Configuration of the Cholecalciferol-Isoxazoline AdductsThe conformation and configuration of compounds 1-4, generated by 1,3-dipolar addition of nitrile oxides to the exomethylene group of (5Z)- and (5E)-vitamin D3 has been assigned. A combination of force-field calculations, LIS measurements, LIS simulations and CD spectroscopy has been used. In addition, the assignment has been verified by chemical correlation of 1 and 3 to 5 as well as of 2 and 4 to 6.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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