反应详情

To a stirred suspension of 1-isopropyl-6-methoxy-1H-indole-4-carboxylic acid (700 mg, 3.00 mmol) in MeOH was added H2SO4 (440 mg, 4.50 mmol) and then heated at reflux for 3 h. Methanol was distilled off completely under reduced pressure and the residue basified with saturated aqueous NaHCO3 solution and extracted with ethyl acetate (2×5 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated. The residue was purified by column chromatography (SiO2, 100-200) by eluting 5% ethyl acetate in petroleum ether to afford 1-isopropyl-6-methoxy-1H-indole-4-carboxylic acid methyl ester (240 mg, 32.4%) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 1.45 (d, J=6.8 Hz, 6H), 3.84 (s, 3H), 3.88 (s, 3H), 4.81-4.78 (m, 1H), 6.86 (d, J=3.2 Hz, 1H), 7.34 (d, J=2.4 Hz, 1H), 7.39 (d, J=2 Hz, 1H), 7.54 (d, J=3.6 Hz, 1H). LCMS (ES+): m/z=248.16[M+H].

1. temperatureheated
2. temperatureat reflux for 3 h
3. distillationMethanol was distilled off completely under reduced pressure
4. extractionextracted with ethyl acetate (2×5 mL)
5. dry with materialThe combined organic layers were dried over anhydrous Na2SO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was purified by column chromatography (SiO2, 100-200)
9. washby eluting 5% ethyl acetate in petroleum ether