title: The first regioselective metalation and functionalization of unprotected 4-halobenzoic acids.
abstract: [reaction: see text] By treatment with s-BuLi, s-BuLi/TMEDA, or t-BuLi at approximately -78 degrees 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 Me(2)S(2) and I(2).
authors.affiliation: Université du Maine and CNRS, Unité de chimie organique moléculaire et macromoléculaire (UMR 6011), Faculté des sciences, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gohier
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Castanet
authors.forename: Jacques
authors.initials: J
authors.lastname: Mortier