反应详情

To a solution of the product of step b (750 mg, 2.06 mmol) in ethanol (45 ml) was added sodium hydroxide (5 ml of 6.0M solution). The mixture was heated at reflux for 48 h, it was allowed to cool to room temperature and concentrated to small volume under reduced pressure. The concentrated solution was diluted with 2M hydrochloric acid (40 ml), the precipitated solid was filtered, washed with water and dried to afford the acid (660 mg, 94%). 1H NMR (300 MHz, CDCl3) 11.5 (1H, br s), 8.26 (1H, br s), 7.48 (2H, m), 7.40 (2H, m), 7.26 (1H, m), 6.94 (1H, d), 2.87 92H, s), 1.97 (3H, br s), 1.63 (12H, m).

1. temperatureThe mixture was heated
2. temperatureat reflux for 48 h
3. concentrationconcentrated to small volume under reduced pressure
4. additionThe concentrated solution was diluted with 2M hydrochloric acid (40 ml)
5. filtrationthe precipitated solid was filtered
6. washwashed with water
7. customdried