Directed Ortho-Metalation of Unprotected Benzoic Acids. Methodology and Regioselective Synthesis of Useful Contiguously 3- and 6-Substituted 2-Methoxybenzoic Acid Building Blocks

Thi-Huu Nguyen, Anne-Sophie Castanet, and Jacques Mortier*
Universit du Maine and CNRS, Unit de Chimie Organique Molculaire et Macromolculaire (UMR 6011), Facult des Sciences, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
Org. Lett., 2006, 8 (4), pp 765–768
DOI: 10.1021/ol0530427
Publication Date (Web): January 21, 2006
Copyright © 2006 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, jacques.mortier@univ-lemans.fr

Abstract

Abstract Image

By treatment with s-BuLi/TMEDA at −78 °C, unprotected 2-methoxybenzoic acid is deprotonated exclusively in the position ortho to the carboxylate. A reversal of regioselectivity is observed when the acid is treated with n-BuLi/t-BuOK. These results are of general utility for the one-pot preparation of a variety of very simple 3- and 6-substituted 2-methoxybenzoic acids that are not easily accessible by conventional means. The potential usefulness of the method is demonstrated by the expedient synthesis of lunularic acid.

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History

  • Published In Issue February 16, 2006
  • Received December 15, 2005

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