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http://dx.doi.org/10.18419/opus-11653
Autor(en): | Picher, Marie-Idrissa |
Titel: | Metal-catalyzed formation of 3- and 4-membered rings |
Erscheinungsdatum: | 2021 |
Dokumentart: | Dissertation |
Seiten: | xii, 362 |
URI: | http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-116707 http://elib.uni-stuttgart.de/handle/11682/11670 http://dx.doi.org/10.18419/opus-11653 |
Zusammenfassung: | The catalytic activity of TBA[Fe] in the cyclopropanation of aryl olefins using diazo esters as carbene surrogates was investigated. By employing two modes of activation for the catalyst, i.e. thermal or photochemical, a variety of aryl olefins as well as 1,3-enynes were converted to the corresponding cyclopropanes in moderate trans-selectivity and good to excellent yields.The catalytic process exhibited good functional group tolerance and chemoselectivity, as triple bonds and non-conjugated olefins remained unaffected, and no competing X-H insertion reaction was observed. Mechanistic studies allowed to determine that the catalyst was activated by either photochemical or thermal decarbonylation. Moreover, the presence of 4-nitroanisole in sub-stoichiometric amounts was shown to accelerate decarbonylation of the catalyst under thermal conditions and enhance its activity. In addition, a novel silver-catalyzed oxidative ring expansion of propargyl cyclopropanes was developed to give a straightforward access to valuable synthetic intermediates. Enantiopure cyclobutenyl ketones were obtained from chiral cis-propargyl cyclopropanes under mild conditions with almost full retention of their enantiomeric excess and up to 92 % yield. The reaction exhibited so far good functional group tolerance and mechanistic investigations as well as expansion of the substrate scope are currently under way in our laboratories. |
Enthalten in den Sammlungen: | 03 Fakultät Chemie |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
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Ph.D._Thesis_MIP_Final_OPUS.pdf | 9,6 MB | Adobe PDF | Öffnen/Anzeigen |
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