Theoretical Prediction of a Perepoxide Intermediate for the Reaction of Singlet Oxygen with trans-Cyclooctene Contrasts with the Two-Step No-Intermediate Ene Reaction for Acyclic Alkenes
| Autor: | Christopher S. Foote, K. N. Houk, Andrew G. Leach |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
chemistry.chemical_classification
Reaction mechanism Singlet Oxygen Chemistry Diradical Singlet oxygen Alkene Organic Chemistry Alkenes Models Theoretical Photochemistry Hydrogen atom abstraction Cyclooctanes chemistry.chemical_compound Models Chemical Epoxy Compounds Singlet state Isomerization Ene reaction |
| Zdroj: | The Journal of Organic Chemistry. 73:8511-8519 |
| ISSN: | 1520-6904 0022-3263 |
| Popis: | B3LYP/6-31G* and CASMP2 calculations have been employed to study the ene reaction of singlet oxygen with trans-cyclooctene. These methods predict that the reaction involves a perepoxide intermediate, whereas alkenes such as tetramethylethylene are predicted by the same methods to occur by a two-step no-intermediate mechanism, with no perepoxide intermediate. The change in mechanism arises because the trans-cyclooctene imposes a substantial strain in the transition state for hydrogen abstraction. The perepoxide is formed through a polarized diradical intermediate that can lead to the observation of alkene isomerization. The polarized diradical also becomes a minimum because of the barrier to abstraction. |
| Databáze: | OpenAIRE |
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