反应详情

温度

60 °C

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and reflux condenser was charged with 28 (400 mg, 0.642 mmol), THF (5 mL) and ethanol (5 mL). A solution of lithium hydroxide (124 mg, 10.2 mmol) in water (5 mL) was added, and the mixture was heated at 60° C. for 48 h. After this time, the reaction was cooled to room temperature, and the mixture was slowly acidified to pH 4.0 with 10% aqueous citric acid. The resulting precipitate was filtered, and the filter cake was washed with water (20 mL), then triturated with a 1:10 mixture of methylene chloride/ethyl acetate (20 mL). The resulting residue was dried to a constant weight under vacuum at 45° C. to afford 29 in 55% yield (210 mg) as an off-white solid: mp 197-198° C.; 1H NMR (500 MHz, DMSO-d6) δ 9.91 (s, 1H), 9.29 (s, 1H), 7.99 (d, 2H, J=8.5 Hz), 7.95 (d, 2H, J=8.5 Hz), 7.55 (d, 2H, J=8.5 Hz), 7.39 (d, 2H, J=8.5 Hz), 7.35 (dd, 1H, J=7.0, 1.5 Hz), 7.32-7.28 (m, 2H), 7.24 (s, 1H), 4.23 (s, 1H), 3.56 (s, 3H), 3.30 (m, 1H), 2.30 (s, 3H), 2.23 (s, 3H), 1.33 (s, 9H), 1.13 (d, 3H, J=6.5 Hz), 1.10 (d, 3H, J=6.5 Hz); MS (ESI+) m/z 596 (M+H).

1. customA 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer
2. temperaturereflux condenser
3. temperatureAfter this time, the reaction was cooled to room temperature
4. filtrationThe resulting precipitate was filtered
5. washthe filter cake was washed with water (20 mL)
6. customtriturated with a 1:10 mixture of methylene chloride/ethyl acetate (20 mL)
7. customThe resulting residue was dried to a constant weight under vacuum at 45° C.