DFT study on the molecular mechanism of the [4 + 2] cycloaddition between thiobenzophenone and arylalkenes via radical cations
The mechanistic aspects of the radical cationic version of the [4 + 2] cycloaddition between thiobenzophenone 1 and three aryl-substituted alkenes 2a-c have been studied using DFT methods at the UB3LYP/6-31G level of theory. In the ground state, the Diels-Alder reaction follows an asynchronous conce...
| Authors: | , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2009 |
| Country: | Argentina |
| Institution: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repository: | CONICET Digital (CONICET) |
| Language: | English |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/82615 |
| Online Access: | http://hdl.handle.net/11336/82615 |
| Access Level: | Open access |
| Keyword: | Dft Ion-Molecule Complex Radical Cation Reactivity https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Summary: | The mechanistic aspects of the radical cationic version of the [4 + 2] cycloaddition between thiobenzophenone 1 and three aryl-substituted alkenes 2a-c have been studied using DFT methods at the UB3LYP/6-31G level of theory. In the ground state, the Diels-Alder reaction follows an asynchronous concerted mechanism; the large activation energy associated with bond formation prevents this process. After generation of the radical cation (RC), formation of a molecular complex (MC) between 1 and 2a-c initiates a stepwise mechanism, with attack of the sulfur atom of 1 to the aryl-conjugated position of 2a-c. Subsequent ring closure is the rate-determining step of these cycloadditions. Methoxy or dimethylamino substitution at the aryl group, while stabilizing the corresponding RC, results in a less exothermic formation of MC and a significant increase of the cycloaddition barrier. |
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