反应详情

温度

80 °C

3.4 g (12 mmol) of the title compound from Example 2 are warmed to 80° C. in 5 ml of glacial acetic acid and 10 ml of acetic anhydride are added dropwise at this temperature with stirring. The mixture is then warmed to 110°-120° C. for 2 hours, allowed to cool to 80° C., 10 ml of methanol are added, the mixture is heated to reflux for a further 15 minutes and subsequently concentrated. The residue is taken up in 10 ml of methanol and rapidly added dropwise at 10° C. to 50 ml of 2N methanolic NaOH. The solution is then clarified over charcoal, concentrated, the residue treated with 50 ml, extracted three times using 50 ml of dichloromethane, and the organic phase dried and concentrated. The crystallized residue is triturated with a petroleum ether/diisopropyl ether mixture (1:1), and the product is filtered off with suction, washed with a little diisopropyl ether and dried in vacuo, m.p. 96°-98° C.

1. temperatureThe mixture is then warmed to 110°-120° C. for 2 hours
2. temperaturethe mixture is heated
3. temperatureto reflux for a further 15 minutes
4. concentrationsubsequently concentrated
5. additionrapidly added dropwise at 10° C. to 50 ml of 2N methanolic NaOH
6. concentrationconcentrated
7. additionthe residue treated with 50 ml
8. extractionextracted three times
9. customthe organic phase dried
10. concentrationconcentrated
11. customThe crystallized residue is triturated with a petroleum ether/diisopropyl ether mixture (1:1)
12. filtrationthe product is filtered off with suction
13. washwashed with a little diisopropyl ether
14. customdried in vacuo, m.p. 96°-98° C.