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General procedure for the synthesis of 3-amino-4-methyl-2-nitrobenzoic acid from 3-acetamido-4-methyl-2-nitrobenzoic acid: To a solution of 3-acetamido-4-methyl-2-nitrobenzoic acid (79 g, 0.33 mol, 1.0 eq.) in dioxane (400 mL) was added dropwise 6N hydrochloric acid (200 mL). The reaction mixture was heated under reflux conditions overnight. Upon completion of the reaction, it was extracted with ethyl acetate (200 mL × 3). The organic phases were combined and dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. The resulting solid was ground with mixed solvents (petroleum ether/ethyl acetate = 10/1, v/v) and filtered to give 3-amino-4-methyl-2-nitrobenzoic acid (60 g, 92.7% yield).

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