The First Regioselective Metalation and Functionalization of Unprotected 4-Halobenzoic Acids

19 January 2005

journal article
research article
Published by American Chemical Society (ACS) in The Journal of Organic Chemistry

Vol. 70 (4) , 1501-1504
https://doi.org/10.1021/jo0483365

Abstract

By treatment with s-BuLi, s-BuLi/TMEDA, or t-BuLi at ∼−78 °C, 4-fluoro- and 4-chlorobenzoic acids (1a,b) are metalated preferentially in the position adjacent to the carboxylate. A complete reversal in regioselectivity is observed for 1a when treated with LTMP; a sequential process involving a rapid intraaggregate lithiation through a quasi dianion complex “QUADAC” is postulated to explain the unusual reactivity of Me₂S₂ and I₂.

Keywords

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