Synthesis of methyl 3-methoxy-5-aminobenzoate (2): 2 g (9.5 mmol) of methyl 3-methoxy-5-nitrobenzoate (7) was dissolved in 50 mL of methanol and heated until dissolved. Subsequently, 0.3 g of Pd/C (10%) was added and 2.99 g (47.5 mmol) of ammonium formate was added under nitrogen protection. The reaction mixture was refluxed for 3 h, after which stirring was continued overnight at room temperature. Upon completion of the reaction, the clear solution of the upper layer of catalyst was carefully decanted and filtered through a syringe filter. The catalyst remaining in the flask was washed twice with methanol and the filtrates were combined. The filtrate was concentrated to give 1.69 g of brown crude product, which was purified by column chromatography (eluent: hexane/ethyl acetate, 7:3). After vacuum drying, 1.25 g (73% yield) of colorless solid product was obtained. The product was confirmed by 1H NMR (CDCl3): δ 7.00-6.97 (m, 2H), 6.42 (t, J1 = 2.2 Hz, J2 = 2.2 Hz, 1H), 3.89 (s, 3H, OCH3), 3.80 (s, 3H, OCH3), 3.78 (s, 2H, NH2); 13C NMR (CDCl3) δ 167.13, 160.71, 147.49, 131.95, 109.01, 105.71, 104.36, 55.19, 51.88. ESI-MS m/z 314 [MH]+.
