Abstract
The reactions of 3-fluoro-4-chloronitrobenzene and of 3,5-difluoro-4-chloronitrobenzene with thiophenoxide anion lead to predominant substitution of the chlorine atom through SNAr orbital-controlled processes. However, when harder nucleophiles (methoxide anion) are used, the substitution of a fluorine atom meta with respect to the activating nitro group becomes apparent in the reaction of 3-fluoro-4-chloronitrobenzene, predominant in the reaction of 5-fluoro-4-chloro-3-methoxynitrobenzene, and almost exclusive in the reaction of 3,5-difluoro-4-chloronitrobenzene. Kinetic measurements and theoretical calculations indicate that the observed meta substitution of a fluorine atom is a SNAr charge-controlled reaction with a loosely bonded transition state.
Original language | English |
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Pages (from-to) | 2557-2564 |
Journal | Tetrahedron |
Volume | 52 |
Issue number | 7 |
DOIs | |
Publication status | Published - 12 Feb 1996 |