反应详情

温度

0 °C

25 g (203 mmol) of isonicotinic acid, 35.12 g (243.7 mmol) of 2,2-dimethyl-1,3-dioxolane-4,6-dione and 49.6 g (406 mmol) of 4-dimethylaminopyridine are initially charged in 300 ml of dichloromethane, and the mixture is cooled to 0° C. A 1N solution of 46.1 g (223.4 mmol) of 1,3-dicyclohexylcarbodiimide in dichloromethane is added dropwise. The mixture is stirred at room temperature for 2 hours. The precipitate formed is filtered off and washed with dichloromethane. The filtrate is concentrated under reduced pressure. The residue is dissolved in 1200 ml of ethanol, a solution of 96.6 g (507.7 mmol) of p-toluenesulfonic acid monohydrate in 300 ml of ethanol is added and the mixture is stirred under reflux for one hour. After cooling, the ethanol is removed under reduced pressure. The residue is taken up in 1000 ml of ethyl acetate and 900 ml of water and dissolved by heating. The organic phase is separated off, washed with 600 ml of saturated sodium bicarbonate solution and saturated sodium chloride solution and dried over sodium sulfate. The mixture is concentrated under reduced pressure. The crude product is filtered through a silica gel frit using dichloromethane/methanol 10:1. Since there is still product present in the aqueous phase, it is extracted with dichloromethane and the extract is dried over sodium sulfate and concentrated under reduced pressure. The crude product is filtered through a silica gel frit using dichloromethane/methanol 10:1. This gives a total of 25.9 g (42% of theory) of product.

1. customThe precipitate formed
2. filtrationis filtered off
3. washwashed with dichloromethane
4. concentrationThe filtrate is concentrated under reduced pressure
5. dissolutionThe residue is dissolved in 1200 ml of ethanol
6. stirringthe mixture is stirred
7. temperatureunder reflux for one hour
8. temperatureAfter cooling
9. customthe ethanol is removed under reduced pressure
10. dissolution900 ml of water and dissolved
11. temperatureby heating
12. customThe organic phase is separated off
13. washwashed with 600 ml of saturated sodium bicarbonate solution and saturated sodium chloride solution
14. dry with materialdried over sodium sulfate
15. concentrationThe mixture is concentrated under reduced pressure
16. filtrationThe crude product is filtered through a silica gel frit
17. extractionis extracted with dichloromethane
18. dry with materialthe extract is dried over sodium sulfate
19. concentrationconcentrated under reduced pressure
20. filtrationThe crude product is filtered through a silica gel frit
21. customThis gives a total of 25.9 g (42% of theory) of product