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  • 1
    Electronic Resource
    Electronic Resource
    Stereochemie von Metallocenen, 44. Mitt.: Darstellung und Konfiguration von Tricarbonylchrom-Komplexen der Diphensäure und ihrer Derivate 3. Mitt. über Biphenyl-tricarbonylchrom-Komplexe (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 259-274 
    Details
    ISSN: 1434-4475
    Keywords: Benchrotrenes ; Hydrogen bridges, intramolecular ; Lactone of 2′-hydroxymethyl-biphenyl-2-carboxylic acid, mono and bis tricarbonylchromium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mono and bis tricarbonylchromium complexes of diphenic acid and its monomethylester (3, 4, 15, 16) were prepared by treating the corresponding methyl and trimethylsilylesters (e.g.12) with Cr(CO)6 and subsequent hydrolysis of the complexes1, 2, 13, and14. Diborane reduction of the carboxylic acids gave hydroxymethyl derivatives, amongst which the diol8 a is a key substance for configurational analyses by1H-nmr and ir spectroscopy. In this context monosubstituted biphenyl complexes (9–11) were prepared as reference substances. Complexation of the lactone23 of 2′-hydroxymethyl biphenyl-2-carboxylic acid afforded (besides two isomeric monocomplexes) mainly thetrans-biscomplex26 b, a key intermediate for ring opening and cyclization reactions. The stereochemical possibilities of the biscomplexes are discussed. The “racemate” configuration is preliminarily assigned to diphenic acid bistricarbonylchromium and its derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00938733
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  • 2
    Electronic Resource
    Electronic Resource
    Biphenyl-tricarbonylchrom-komplexe, 9. Mitt.: Synthesen, chromatographische Enantiomerentrennung, Circulardichroismus und Chiralität von mono- und bis-(Tricarbonylchrom)-Komplexen di- und tetrasubstituierter sowie überbrückter Biphenyle (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1429-1442 
    Details
    ISSN: 1434-4475
    Keywords: Triacetylcellulose ; Recycling technique ; Enantiomeric purity ; Metallocene chirality ; Axial chirality ; Conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Chiral title compounds have been resolved by medium pressure liquid chromatography (MPLC) on triacetylcellulose in ethanol. Whereas a quantitative separation was achieved for16 and20, a recycling technique had to be applied to1,4,6,10 and15 leading to a 100% e.e. for1,6 and15 and to ca. 60% e.e. for4 and10. An unambiguous assignment of the chirality (+)-(R) a -(S) m for tricarbonylchromium-6,6′-dimethyl-diphenicacid dimethylester (4) was deduced both from the photochemical decomplexation to (-)-5 with the known chirality (R) a (whose e.e. was determined by MPLC on triacetylcellulose) and by comparison of the1H-n.m.r. spectra of4 and5 thereby proving the structure 4 for the former. Other chiralities both for mono and bis(tricarbonylchromium)biphenyl complexes were established by chemical correlations and comparison of the CD spectra with those of key compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816342
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  • 3
    Electronic Resource
    Electronic Resource
    A recycling technique for the chromatographic separation of enantiomers and diastereomers on triacetylcellulose (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1113-1120 
    Details
    ISSN: 1434-4475
    Keywords: Enantiomeric purity ; Centro-, Axial- and Planarchiral Arenes and Metallocenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird eine einfache und preisgünstige Anlage zur Racematspaltung und Trennung von Diastereomeren an Triacetylcellulose in Ethanol unter erhöhtem Druck beschrieben. Sie beinhaltet einen geschlossenen Lösungsmittelkreislauf (Pumpe — Säule — Detektor — Pumpe) und ermöglicht eine kontinuierliche Arbeitsweise bis zu etwa 16 Zyklen, ohne den Fluß unterbrechen oder die Fraktionen handhaben zu müssen. Diese offensichtlich universelle Methode, welche auch die Ermittlung enantiomerer Reinheiten erlaubt, wird an Hand von einigen zentro-, axial- und planarchiralen Arenen und Metallocenen vorgestellt.
    Notes: Abstract A simple and inexpensive equipment for the optical resolution of enantiomers (and separation of diastereomers) on triacetylcellulose in ethanol at elevated pressure is described. It involves a closed circuit of solvent (pump—column—detector—pump) allowing a continuous chromatography up to 16 cycles without stopping the flow or handling fractions. This useful and versatile method permitting also the determination of enantiomeric purities is illustrated by several examples of centro-, axial- and planarchiral arenes and metallocenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798778
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