Induzierte Selektivität : die Entwicklung der assistierten Vinylkationenbildung und Anwendung der resultierenden Vinyltriflimide
| Autor: | Schröder, Sebastian |
|---|---|
| Přispěvatelé: | Niggemann, Meike, Albrecht, Markus |
| Jazyk: | němčina |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Aachen 1 Online-Ressource (290 Seiten) : Illustrationen, Diagramme (2020). doi:10.18154/RWTH-2021-00150 = Dissertation, RWTH Aachen University, 2020 |
| DOI: | 10.18154/RWTH-2021-00150 |
| Popis: | Dissertation, RWTH Aachen University, 2020; Aachen 1 Online-Ressource (290 Seiten) : Illustrationen, Diagramme (2021). = Dissertation, RWTH Aachen University, 2020 In the context of the work "Induced Selectivity – The Development of Assisted Vinyl Cation Formation and Application of the Resulting Vinyltriflimide", the use of reactive vinyl cations was successfully implemented in a number of new transformations. Initially, the first transition-metal-free cycloisomerization of diynols was developed as a simple and efficient method for the formation of 2H-pyranes and dienones. Various mechanism experiments, the detailed analysis of the scope of application and a complementary NMR study were able to illuminate the mechanism and identify the steric claim and the ability to realize conjugated systems as central factors for the balance between 2H-pyrane and dienone. Based on the observed stabilization of reactive vinyl cations by electron donors, the concept of assisted vinyl cation formation was subsequently developed. This was the first time that high levels of chemo-, regio- and stereoselectivity were achieved in the transition-metal-free electrophilic addition to alkynes. The use of a lithium cluster thus formally led to the asynchronously concerted [2+2]-addition of HNTf2 with Markovnikow selectivity. The possibility of selectively adding the bistriflimide, which until now had been used almost exclusively as a weak-coordinating anion, as an extremely weak nucleophile in the presence of nucleophiles such as water illustrates the potential of the assisted vinyl cation formation developed in this work. Finally, the reactivity of the novel products of bistriflimide addition, the vinyl triflimides, was investigated. A photo-induced carbotrifluoromethylation of these substrates could be realized. By using the triflimide group as a source of trifluoromethyl radicals, expensive trifluoromethylation reagents and harsh reaction conditions were avoided. This enables the successful conversion of intermediate-emerging novel sulfonylimines with various nucleophiles. In addition, the conducted control experiments and supplementary DFT calculations provide a deeper insight into the reaction and strongly point to a radical-chain mechanism. Published by Aachen |
| Databáze: | OpenAIRE |
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