In:
Australian Journal of Chemistry, CSIRO Publishing, Vol. 69, No. 3 ( 2016), p. 307-
Abstract:
The alkyl and aryllithium nucleophilic aromatic substitution (SNAr) displacement of a fluoro or methoxy group from unprotected 2-fluoro/methoxybenzoic acids is discussed. It was discovered that a TMS group located at the C6-position ortho to the carboxyl group shields effectively the carboxylate against nucleophilic attack, thus reducing dramatically ketone formation, and reorients nucleophilic substitution to the C2-position. The reactions with fluoro-substituted substrate 7 proceed efficiently; in contrast, the use of methoxy-functionalized benzoic acid 8 only affords moderate yields with s-BuLi and PhLi. This uncatalyzed coupling reaction, which provides a direct access to biaryl compounds, presumably proceeds by an addition–elimination sequence via intermediate formation of a resonance-stabilized pentavalent silalactone-Meisenheimer complex.
Type of Medium:
Online Resource
ISSN:
0004-9425
Language:
English
Publisher:
CSIRO Publishing
Publication Date:
2016
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