A suspension was prepared by dissolving 4-amino-2-nitrobenzoic acid (200 mg, 1.10 mmol) and sodium carbonate (349 mg, 3.29 mmol) in dimethylformamide (5.5 mL). Subsequently, iodomethane (0.21 mL) was added to the suspension and the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, water was added to the reaction solution and extracted with ethyl acetate. The organic layers were combined and washed sequentially with saturated aqueous ammonium chloride solution and saturated aqueous sodium chloride solution, and then dried over anhydrous sodium sulfate. Concentration of the organic layer by decompression afforded 216 mg of the target product, methyl 4-amino-2-nitrobenzoate, as a yellow solid (100% yield). The product was confirmed by ^1H-NMR (CDCl3, ppm): δ 7.69 (d, J = 8.5 Hz, 1H), 6.85 (d, J = 2.4 Hz, 1H), 6.77 (dd, J = 2.4, 8.5 Hz, 1H), 4.31 (bs, 2H), 3.84 (s, 3H). lC/MS (ESI) showed the molecular ions peaks as 196.
