| Autor: |
Filippone S; Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain., Barroso MI, Martín-Domenech A, Osuna S, Solà M, Martín N |
| Jazyk: |
angličtina |
| Zdroj: |
Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2008; Vol. 14 (17), pp. 5198-206. |
| DOI: |
10.1002/chem.200800096 |
| Abstrakt: |
In contrast to N-methyl or N-unsubstituted pyrrolidinofullerenes, which efficiently undergo the retrocycloaddition reaction to quantitatively afford pristine fullerene, N-benzoyl derivatives do not give this reaction under the same experimental conditions. To unravel the mechanism of the retrocycloaddition process, trapping experiments of the in-situ thermally generated azomethine ylides, with an efficient dipolarophile were conducted. These experiments afforded the respective cycloadducts as an endo/exo isomeric mixture. Theoretical calculations carried out at the DFT level and by using the two-layered ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach underpin the experimental findings and predict that the presence of the dienophile is not a basic requirement for the azomethine ylide to be able to leave the fullerene surface under thermal conditions. Once the 1,3-dipole is generated in the reaction medium, it is efficiently trapped by the dipolarophile (maleic anhydride or N-phenylmaleimide). However, for N-unsubstituted pyrrolidinofullerenes, the participation of the dipolarophile in assisting the 1,3-dipole to leave the fullerene surface throughout the whole reaction pathway is also a plausible mechanism that cannot be ruled out. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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