Synthesis
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).
References
[1] Patent: WO2018/218070, 2018, A2. Location in patent: Page/Page column 181; 182
[2] Patent: WO2015/27222, 2015, A2. Location in patent: Paragraph 0279
[3] Patent: WO2007/76092, 2007, A2. Location in patent: Page/Page column 71
[4] Patent: US2004/167194, 2004, A1. Location in patent: Page 23
