The use of carboxylic acids as traceless directing groups for regioselective C-H bond functionalisation
Marc Font1, Jacob M Quibell1, Gregory J P Perry1
1School of Chemistry, University of Manchester, Oxford Road, M13 9PL, Manchester, UK. igor.larrosa@manchester.ac.uk.
Abstract:
The ability to selectively functionalise a specific C-H bond is a long-standing challenge due to the ubiquity of such bonds in organic molecules. One of the most common approaches to overcome this obstacle consists of installing directing groups into substrates to direct the functionalisation towards the desired C-H bond, leaving behind the directing group in the molecule. Alternatively, carboxylic acids have been employed as traceless directing groups that are easily removed after carboxylic acid-directed installation of the desired functionality. This review focuses on the development of this concept and its application to organic synthesis during the last decade.
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Relative Reactivity of Carboxylic Acid Derivatives
A key factor in assessing the reactivity of the acid derivatives is the basicity of the substituent or the leaving group. The lower the basicity of the leaving group, the higher the reactivity of the derivative. The basicity of the leaving group follows this order:
Halide ions < Acyloxy ions < Alkoxy ions < Amine ions


