The use of carboxylic acids as traceless directing groups for regioselective C-H bond functionalisation

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.