反应详情

Tin (II) chloride dihydrate (15.0 g, 66.5 mmol) was added to a suspension of 7-nitro-benzofuran-4-carboxylic acid methyl ester (4.82 g, 21.8 mmol) in ethyl acetate (80 mL) and ethanol (80 mL). The reaction mixture was stirred at room temperature for four days then partitioned between ethyl acetate and saturated aqueous solution of potassium carbonate. The organic extract was washed with brine, dried (anhydrous sodium sulfate) and concentrated under reduced pressure. The residue was purified by flash column chromatography over silica gel eluting with 30% ethyl acetate in hexane give 7-amino-benzofuran-4-carboxylic acid methyl ester (3.67 g, 88%). 1H NMR (CDCl3) δ: 3.92 (s, 3H), 6.60 (d, 1H, J=8.2 Hz), 7.34 (d, 1H, J=2.1 Hz), 7.67 (d, 1H, J=2.1 Hz), 7.84 (d, 1H, J=8.2 Hz).

1. customthen partitioned between ethyl acetate and saturated aqueous solution of potassium carbonate
2. extractionThe organic extract
3. washwas washed with brine
4. dry with materialdried (anhydrous sodium sulfate)
5. concentrationconcentrated under reduced pressure
6. customThe residue was purified by flash column chromatography over silica gel eluting with 30% ethyl acetate in hexane