反应详情

温度

23 °C

A mixture of N-(butoxycarbonyl)-β-alanine (prepared in Stage 393.3; 3.27 g; 0.0173 mol) and cesium carbonate (2.81 g; 0.0087 mol) in 50 ml of methanol is stirred at 23° C. for 1 hour. The methanol is eliminated by evaporation under reduced pressure in a rotary evaporator. The mixture obtained is dissolved in 50 ml of dimethylformamide then intermediate 393.2 (5 g; 0.0173 mol) is added. After stirring for 16 hours, the solvent is evaporated off under reduced pressure. The mixture obtained is taken up in ethyl acetate then the cesium bromide is filtered. The ethyl acetate of the filtrate is evaporated off and the reaction oil is taken up in a mixture of xylene (80 ml) and ammonium acetate (26.6 g; 0.35 mol). The reaction medium is heated under reflux for approximately 1 hour 30 minutes while eliminating the water using a Dean-Stark then, after cooling down, a mixture of ice-cold water and ethyl acetate is poured into the reaction medium. After decanting, the organic phase is washed with a saturated solution of sodium bicarbonate, dried over magnesium sulphate then evaporated under vacuum. After purification on a silica column (eluent: CH2Cl2-ethanol/9-1), a colourless oil is obtained which crystallizes from a mixture of isopentane and isopropyl ether. After filtration and drying a white coloured powder is obtained (3.31 g, yield of 50%). Melting point: 143-144° C. MH+=378.2.

1. customThe methanol is eliminated by evaporation under reduced pressure in a rotary evaporator
2. customThe mixture obtained
3. stirringAfter stirring for 16 hours
4. customthe solvent is evaporated off under reduced pressure
5. customThe mixture obtained
6. filtrationthe cesium bromide is filtered
7. customThe ethyl acetate of the filtrate is evaporated off
8. customthe reaction oil
9. temperatureThe reaction medium is heated
10. temperatureunder reflux for approximately 1 hour 30 minutes
11. temperatureafter cooling down
12. additionis poured into the reaction medium
13. customAfter decanting
14. washthe organic phase is washed with a saturated solution of sodium bicarbonate
15. dry with materialdried over magnesium sulphate
16. customthen evaporated under vacuum
17. customAfter purification on a silica column (eluent: CH2Cl2-ethanol/9-1)
18. customa colourless oil is obtained which
19. customcrystallizes from a mixture of isopentane and isopropyl ether
20. filtrationAfter filtration
21. customdrying a white coloured powder
22. customis obtained (3.31 g, yield of 50%)