反应详情

A solution of BF3 etherate (42 ml) in diethylene glycol dimethyl ether (42 ml) is added dropwise to a cooled mixture of 1-methyl-4-(2,4,6-trimethoxyphenyl)-1,2,3,6-tetrahydropyridine (20 g) and sodium borohydride (12 g) in diethylene glycol dimethyl ether (140 ml). The mixture is heated for one hour to 50° C., and the cooled reaction mixture is then treated with water (20 ml) and then with concentrated HCl (116 ml). The mixture is stirred for two hours at 50°-60° C., cooled and rendered alkaline with sodium hydroxide solution. Hydrogen peroxide solution (30%, 20 ml) is then added and the mixture is heated with stirring for two hours at 50°-60° C. The solution is cooled and extracted with ethyl acetate. The ethyl acetate extract is concentrated in vacuo. The residue is acidified with 2N HCl and extracted with ethyl acetate, and the organic layer is separated off. The aqueous layer is then rendered alkaline with sodium hydroxide solution and extracted with ether. The ether extract is washed with brine, dried over sodium sulfate and concentrated, a solid residue being obtained which is recrystallized from hot water, which gives trans-3-hydroxy-4-(2,4,6-trimethoxyphenyl)-1-methylpiperidine (12 g). Yield: 12 g; melting point 88°-89° C.

1. temperatureThe mixture is heated for one hour to 50° C.
2. customthe cooled reaction mixture
3. temperaturecooled
4. temperaturethe mixture is heated
5. stirringwith stirring for two hours at 50°-60° C
6. temperatureThe solution is cooled
7. extractionextracted with ethyl acetate
8. extractionThe ethyl acetate extract
9. concentrationis concentrated in vacuo
10. extractionextracted with ethyl acetate
11. customthe organic layer is separated off
12. extractionextracted with ether
13. extractionThe ether extract
14. washis washed with brine
15. dry with materialdried over sodium sulfate
16. concentrationconcentrated
17. customa solid residue being obtained which
18. customis recrystallized from hot water, which