[GRAPHICS] A product and time-resolved kinetic study on the reactivity of tertiary arylcarbinyloxyl radicals bearing a-cyclopropyl and a-cyclobutyl groups has been carried out. Both the 1-cyclopropyl-1-phenylethoxyl (1(.)) and alpha,alpha-dicyclopropylphenylmethoxyl (2(.)) radicals undergo beta-scission to give cyclopropyl phenyl ketone as the major or exclusive product with rate constants higher than that measured for the cumyloxyl radical. It is proposed that in the transition state for beta-scission of 1(.) and 2(.), formation of the C=O double bond is assisted by overlap with the C-C bonding orbitals of the cyclopropane ring. With tertiary arylcarbinyloxyl radicals bearing a-cyclobutyl groups such as the 1-cyclobutyl-1-phenylethoxyl (4(.)) and 1-cyclobutyl-1-phenylpropoxyl (5(.)) radicals, the fragmentation regioselectivity is essentially governed by the stability of the radical formed by P-scission. Accordingly, 4(.) undergoes exclusive C-cyclobutyl bond cleavage to give acetophenone, whereas with 5(.), competition between C-cyclobutyl and C-ethyl bond cleavage, leading to propiophenone and cyclobutylphenyl ketone in a 2:1 ratio, is observed.
Bietti, M., Gente, G., & Salamone, M. (2005). Structural effects on the beta-scission reaction of tertiary arylcarbinyloxyl radicals. The role of alpha-cyclopropyl and alpha-cyclobutyl groups. JOURNAL OF ORGANIC CHEMISTRY, 70(17), 6820-6826.
Tipologia: | Articolo su rivista |
Citazione: | Bietti, M., Gente, G., & Salamone, M. (2005). Structural effects on the beta-scission reaction of tertiary arylcarbinyloxyl radicals. The role of alpha-cyclopropyl and alpha-cyclobutyl groups. JOURNAL OF ORGANIC CHEMISTRY, 70(17), 6820-6826. |
IF: | Con Impact Factor ISI |
Lingua: | English |
Settore Scientifico Disciplinare: | Settore CHIM/06 - Chimica Organica |
Revisione (peer review): | Sì, ma tipo non specificato |
Tipo: | Articolo |
Rilevanza: | Rilevanza internazionale |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1021/jo050883i |
Stato di pubblicazione: | Pubblicato |
Data di pubblicazione: | 2005 |
Titolo: | Structural effects on the beta-scission reaction of tertiary arylcarbinyloxyl radicals. The role of alpha-cyclopropyl and alpha-cyclobutyl groups |
Autori: | |
Autori: | Bietti, M; Gente, G; Salamone, M |
Appare nelle tipologie: | 01 - Articolo su rivista |