A new versatile methodology for the synthesis of 4-halogenated-6-diethylcarbamoylpyridine-2-carboxylic acids

Convenient syntheses of dipicolinic or chelidamic acid derivatives including 4-X-6-diethylcarbamoyl-pyridine-2-carboxylic acid (X=H, Cl, Br) and 4-chloro-6-(3-oxo-3-phenylpropionyl)pyridine-2-carboxylic acid methyl ester are described. These compounds are important synthons for the synthesis of non-symmetric tridentate aromatic chelating agents as well as for the design of ditopic ligands targeted for the elaboration of functional dimetallic helicates.