反应详情

To a solution of ethyl 3-methyl-4-hydroxybenzofuran-2-carboxylate 20 (5.02 g, 22.8 mmol) in acetone (85 mL) was added sequentially K2CO3 (6.3 g, 45.6 mmol) and methyl iodide (6.47 g, 45.6 mmol). The resulting suspension was heated to reflux with stirring for 15 hours, allowed to cool, diluted with water (125 mL), and acidified with 2N HCl (50 mL). The resulting mixture was extracted with ethyl acetate (1×100 mL then 2×50 mL) and the combined extracts were dried and concentrated to a brown oil. Chromatographic purification (Preparative HPLC, 5% ethyl acetate in hexane as eluant) afforded pure ethyl 3-methyl-4-methoxybenzofuran-2-carboxylate as a colorless oil which crystallized on standing. mp 67°-69° C.; 1H NMR d 1.47 (3H, t, J=6 Hz), 2.78 (3H, s), 3.96 (3H, s), 4.48 (2H, q, J=6 Hz), 6.66 (1H, d, J=8 Hz), 7.16 (1H, d, J=8 Hz), 7.36 (1H, t, J=8 Hz).

1. temperatureThe resulting suspension was heated
2. temperatureto reflux
3. temperatureto cool
4. extractionThe resulting mixture was extracted with ethyl acetate (1×100 mL
5. custom2×50 mL) and the combined extracts were dried
6. concentrationconcentrated to a brown oil
7. customChromatographic purification (Preparative HPLC, 5% ethyl acetate in hexane as eluant)