反应详情

Heat a mixture of 5-formyl-2-hydroxy-benzoic acid (5.0 g, 30.09 mmol) concentrated sulfuric acid (5 mL) in methanol (100 mL) at reflux for 24 h. Cool the mixture to room temperature and concentrate under reduced pressure. Purify the resulting residue by chromatography over silica gel, eluting with hexanes/ethyl acetate (80:20), to provide the title compound as a colorless oil (4.28 g, 79%). 1H NMR (CDCl3, 300 MHz) δ 3.88 (s, 3H), 4.52 (bs, 1H), 7.05 (d, J=8.56 Hz, 1H), 7.84 (d, J=8.56 Hz, 1H), 8.40 (s, 1H), 9.85 (s, 1H); TLC Rf=0.34 (3:1 Hexanes/Ethyl Acetate).

1. temperatureHeat
2. temperatureat reflux for 24 h
3. concentrationconcentrate under reduced pressure
4. customPurify the resulting residue by chromatography over silica gel
5. washeluting with hexanes/ethyl acetate (80:20)