反应详情

22 g of the above-described compound from Example 20 are dissolved, under argon, in a mixture of 60 ml of hydrobromic acid (48% solution) and 150 ml of hydrogen bromide in glacial acetic acid (33% solution), and the mixture is heated, adjusted to the evolution of gas, at reflux. After a total of 5 hours, 300 ml of water are added dropwise, with cooling. The batch is extracted several times with a total of 400 ml of diethyl ether. The combined organic phases are washed four times using 400 ml of water each time, dried over magnesium sulfate and filtered. The solvent is removed in vacuo. 20.5 g of a crystalline solid are obtained, which was purified over a column with silica gel (0.063-0.20 mm) (eluant: n-hexane/ethyl acetate 3:1). The solvent is removed and the product is dried in vacuo. 15.8 g of a beige solid are obtained.

1. temperaturethe mixture is heated
2. temperatureat reflux
3. temperaturewith cooling
4. extractionThe batch is extracted several times with a total of 400 ml of diethyl ether
5. washThe combined organic phases are washed four times
6. dry with materialdried over magnesium sulfate
7. filtrationfiltered
8. customThe solvent is removed in vacuo