Radical 4-exo Cyclizations via Template Catalysis
| Autor: | Karsten Knebel, Asli Cangönül, Andreas Gansäuer, Kim Daasbjerg, Maurice van Gastel, Michael Dolg, Christian Kube, Tim Hangele, Michael Hülsen, Joachim Friedrich |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Molecular Structure
Chemistry Hydrogen bond Radical Organic Chemistry Supramolecular chemistry Substrate (chemistry) Hydrogen Bonding Stereoisomerism General Chemistry Photochemistry Combinatorial chemistry Catalysis law.invention Cyclization law Alkanes Organometallic Compounds Molecule Cyclic voltammetry Electron paramagnetic resonance |
| Zdroj: | Gansäuer, A, Knebel, K, Kube, C, van Gastel, M, Cangönül, A, Daasbjerg, K, Hangele, T, Hülsen, M, Dolg, M & Friedrich, J 2012, ' Radical 4-exo Cyclizations via Template Catalysis ', Chemistry: A European Journal, vol. 18, no. 9, pp. 2591-2599 . https://doi.org/10.1002/chem.201102959 |
| DOI: | 10.1002/chem.201102959 |
| Popis: | The mechanism of catalytic 4-exo cyclizations without gem-dialkyl substitution was investigated by a comparison of cyclic voltammetry, EPR, and computational studies with previously published synthetic results. The most active catalyst is a super-unsaturated 13-electron titanocene(III) complex that is formed by supramolecular activation through hydrogen bonding. The template catalyst binds radicals via a two-point binding that is mandatory for the success of the 4-exo cyclization. The computational investigations revealed that formation of the observed trans-cyclobutane product is not possible from the most stable substrate radical. Instead, the most stable product is formed with the lowest energy of activation from a disfavored substrate in a Curtin-Hammett related scenario. |
| Databáze: | OpenAIRE |
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