Synthesis of Trifunctional Thiazole-Fused Anthranilonitrile and Anthranilic Acid Derivatives

The synthesis of trifunctional isomeric benzothiazoles derived from nitroanthranilic acids and their corresponding anthranilonitrile analogues is studied. Compared to previous work, the reaction sequence affords convenient access to hitherto undescribed 2-cyanobenzothiazoles. For further synthetic applications of these polyfunctional compounds, a hydrolysis–decarboxylation sequence is performed in an acidic medium (HCl or HBr), leading to an enlarged array of relevant building blocks.