3-Methoxyisatoic Anhydride is used as a reagent in the synthesis of Tryptanthrin (T947000) and its analogs as antitubercular agents. 3-Methoxyisatoic Anhydride is also used in the preparation of quinazolin-2-ylamino-quinazolin-4-ols as non-nucleoside inhibitors of bacterial DNA polymerase III.