The first regioselective metalation and functionalization of unprotected 4-halobenzoic acids

F Gohier, AS Castanet, J Mortier

Index: Gohier, Frederic; Castanet, Anne-Sophie; Mortier, Jacques Journal of Organic Chemistry, 2005 , vol. 70, # 4 p. 1501 - 1504

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Citation Number: 33

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.