反应详情

温度

155 °C

Hydrobromic acid (5.9 ml, 109.1 mmol) and then sulphuric acid (2.0 ml, 37.0 mmol) are added dropwise to 4.7 g of compound 21 (17.6 mmol), the reaction medium being refrigerated using a bath of cold water. The reaction medium is then heated at 155° C. for 2 h 30 min, and then poured into 70 ml of cold water. The pH is then adjusted by adding NaHCO3 (pH approximately 9), and the medium is then extracted at the reflux of toluene (70 ml) for 20 min. The organic phase is then collected and the compound 22 is obtained after crystallization at −18° C. overnight, filtration, washing with hexane, and then drying under vacuum: 1.77 g (yield=31%).

1. extractionthe medium is then extracted at the
2. temperaturereflux of toluene (70 ml) for 20 min
3. customThe organic phase is then collected