反应详情

A solution of compound 9 (1.30 g, 3.96 mmol) in a 2.0 N sodium hydroxide/ethanol solution (1/1, v/v, 6 mL) was refluxed for 30 min. After cooling to room temperature, the reaction mixture was acidified (pH=4-5) with acetic acid and cooled to 0° C. The resulting precipitate was removed by filtration and dried in a vacuum oven to afford acid 23 (1.08 g, 3.29 mmol) as a white solid. Yield 91%; mp 242-244° C.; 1H NMR (200 MHz, DMSO-d6) δ 7.97 (d, 1H, J=8 Hz), 8.15 (d, 1H, J=8 Hz), 8.52 (s, 1H), 9.36 (s, 1H); ESI-MS m/z 298.6 [M−H]−.

1. temperaturecooled to 0° C
2. customThe resulting precipitate was removed by filtration
3. customdried in a vacuum oven