کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5213942 | 1383177 | 2016 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: A new model for C-C bond formation processes derived from the Molecular Electron Density Theory in the study of the mechanism of [3+2] cycloaddition reactions of carbenoid nitrile ylides with electron-deficient ethylenes A new model for C-C bond formation processes derived from the Molecular Electron Density Theory in the study of the mechanism of [3+2] cycloaddition reactions of carbenoid nitrile ylides with electron-deficient ethylenes](/preview/png/5213942.png)
The [3+2] cycloaddition (32CA) reactions of the nitrile ylide (NY) with ethylene and with dicyanoethylene (DCE) have been studied using the Molecular Electron Density Theory through DFT calculations at the MPWB1K/6-31G(d) level. The analysis of the electronic structure of NY indicates that it presents a carbenoid structure with an sp2 lone pair at the carbon atom. While the 32CA reaction with ethylene presents a low activation energy, 6.1 kcal molâ1, the transition state structure associated with the 32CA reaction of NY with DCE is located 7.5 kcal molâ1 below the reagents, the reaction being completely regioselective. The topological analysis of the Electron Localisation Function (ELF) along the reaction path permits to establish a new model for the C-C bond formation characterised by the donation of the electron density of an sp2 carbon lone pair to the most electrophilic carbon atom of an electron-deficient ethylene. The carbenoid character of NY allows introducing a new type of 32CA reaction, carbenoid type (cb-type).
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Journal: Tetrahedron - Volume 72, Issue 12, 24 March 2016, Pages 1524-1532