Directed lithiation of unprotected quinolinecarboxylic acids

The lithium salts of quinoline-2-carboxylic acid and 4-methoxyquinoline-2-carboxylic acid undergo deprotonation at C3 when treated with LTMP in THF at −25 and 0°C, respectively. The lithium salts of quinoline-3- and -4-carboxylic acids are more prone to nucleophilic addition; nevertheless, they are deprotonated at C4 and C3, respectively, when treated with LTMP in THF at −50°C.