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  • 1
    Electronic Resource
    Electronic Resource
    Reactions of ε-Caprolactone with (Alkyne)zirconocene Complexes: Investigation of Elemental Steps in Catalytic Ring-Opening Polymerization of Lactones (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1351-1357 
    Details
    ISSN: 1434-1948
    Keywords: ε-Caprolactone complexes ; Zirconocene ; Ring-opening polymerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of Cp2Zr(L)(η2-Me3SiC2SiMe3) (L = THF, pyridine) with ε-caprolactone, cyclohexanone and cycloheptanone result in an insertion of the carbonyl group into the zirconacyclopropene ring system of the alkyne complexes to yield the five-membered metallacyclic spiro-zirconadihydrofurane complexes 1, 3, 4. The product with ε-caprolactone is not stable at room temperature and was identified only by NMR spectra and chemical reactions. Starting from rac-(ebthi)Zr(η2-Me3SiC2SiMe3) with ε-caprolactone and ethylene carbonate under analogous conditions more stable complexes (2, 5) were obtained. Complexes 2 and 3 were characterized by X-ray crystal-structure analysis. Complexes 1 and 2 react with further ε-caprolactone in a catalytic ring-opening polymerization. The polymerization reactions were monitored by NMR spectroscopy.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Ring-Enlargement and Ring-Opening Reactions of Benzoxazole, Thiazoles, and Benzisoxazole by Zirconocene-Alkyne Complexes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 207-211 
    Details
    ISSN: 0009-2940
    Keywords: Zirconocene ; Titanocene ; Benzoxazoles ; Thiazoles ; Benzisoxazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zirconocene alkyne complexes Cp2Zr(L)(Me3SiC2R) (L = Py, THF; R = SiMe3 tBu) react with heterocyclic compounds like benzoxazole and related thiazoles to yield ring-expanded adducts (1-3) and (4, 5) by formal C-X (X = O, S) bond cleavage and coupling with the coordinated alkyne. In the case of benziso-xazole, the alkyne is not coupled but eliminated, and with ring-enlargement of the benzisoxazole a N-bridged dimer (6) is formed. The obtained complexes 1, 3, and 6 were characterized by NMR spectra and crystal structure analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290214
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    Paper (German National Licenses)
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