[CH3:1][C:2]1([CH3:17])[CH2:6][C:5]2=[C:7]([C:14]([O-:16])=[O:15])[CH:8]=[CH:9][C:10]([N+:11]([O-])=O)=[C:4]2[O:3]1.[C:18](=O)([O-])[O-].[Na+].[Na+].C(=O)(O)[O-].[Na+]>C(O)(=O)C.[Fe]>[NH2:11][C:10]1[CH:9]=[CH:8][C:7]([C:14]([O:16][CH3:18])=[O:15])=[C:5]2[C:4]=1[O:3][C:2]([CH3:17])([CH3:1])[CH2:6]22,2-Dimethyl-7-nitro-3H-benzofuran-4-carboxylate 4c (1.20 g, 4.77 mmol) and iron powder (0.80 g, 14.32 mmol) were dissolved in 25 mL of acetic acid. The reaction mixture was stirred for 12 hours. The resulting mixture was added with sodium carbonate and solid sodium bicarbonate to adjust pH to 7 to 8, extracted with ethyl acetate (50 mL×3). The combined organic phase was washed with water (30 mL) and saturated sodium chloride solution (20 mL) successively, then dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound methyl 7-amino-2,2-dimethyl-3H-benzofuran-4-carboxylate 4d (789 mg, yield: 74.6%) as a white solid.
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