Example 6 (Synthesis of methyl 2-amino-4-benzyloxy-5-methoxybenzoate): In a glass reactor equipped with a stirrer, a thermometer, a reflux condenser tube, and a hydrogen balloon, 4.0 g (12.6 mmol) of methyl 4-benzyloxy-5-methoxy-2-nitrobenzoate, 0.2 g of a 3 wt% platinum/carbon catalyst (60% moisture content, manufactured by NE CHEMCAT CORPORATION) and 20 mL of dimethoxyethane. The reaction was stirred at room temperature for 7 hours under hydrogen atmosphere. Upon completion of the reaction, the reaction mixture was allowed to stand for 10 days, followed by filtration. The filtrate was concentrated under reduced pressure to give 3.17 g methyl 2-amino-4-benzyloxy-5-methoxybenzoate as a light brown solid (isolated yield: 87%). The physical property data of the product were as follows: 1H-NMR (CDCl3, δ/ppm): 3.81 (3H, s), 3.83 (3H, s), 5.09 (2H, s), 5.37 (2H, br s), 6.15 (1H, s), 7.31-7.41 (6H, m); CI-MS (m/e): 287 (M+).
