General procedure for the synthesis of 4-amino-2-methoxyphenol from 2-methoxy-4-nitrophenol: A mixed solution of 2-methoxy-4-nitrophenol (3.00 g, 17.7 mmol), 10% palladium-carbon catalyst (300 mg), tetrahydrofuran (100 mL), and methanol (100 mL) was subjected to a hydrogen atmosphere with stirring for 4 h at room temperature. Upon completion of the reaction, insoluble impurities were removed by filtration, followed by distillation under reduced pressure to remove the solvent, to afford 4-amino-2-methoxyphenol as a solid product in a yield of 2.32 g (94.3% yield). The product was characterized by 1H-NMR (CDCl3) with chemical shifts δ of 3.40 (2H, broad peak), 5.50 (1H, broad peak), 6.21 (1H, double peak, J = 8.2, 2.6 Hz), 6.30 (1H, double peak, J = 2.6 Hz), and 8.72 (1H, double peak, J = 8.2 Hz).
