反应详情

3.5-Dimethyl-4-methoxypyridine-N-oxide (61.2 g) obtained in Example 2 was dissolved in CH3OH (458 ml). Dimethylsulfate (38 ml 0.4 moles) was added dropwise during 15 minutes and pH adjusted to 5.0 using 10M NaOH. The mixture was stirred for 15 minutes and thereafter refluxed for 1 hour. An additional amount of dimethylsulfate (3.8 ml, 0.04 moles) was added dropwise and the mixture was refluxed for 1.5 hours. Stirring was continued overnight at room temperature. Thereafter the mixture was heated to reflux and (NH4)2S2O8 (91.2 g, 0.4 moles) dissolved in water (169 ml) was added during 1.75 hours, followed by refluxing for 1.5 hours and stirring at room temperature overnight. Thereafter CH3OH (452 ml) was added. Precipitated salts were filtered off and discarded. After evaporation of CH3OH, the remaining water phase (pH 0.6) was adjusted to pH 10.0 using 10M NaOH (145 ml). The water phase was extracted three times with CH2Cl2. The combined CH2Cl2 phases were dried over Na2SO4, evaporated and dried, yielding 3,5-dimethyl-4-methoxy-2-hydroxymethylpyridine (44.2 g). The identity of the product was confirmed with 1H and 13C NMR and the purity checked with gas chromatography.

1. temperaturerefluxed for 1 hour
2. temperaturethe mixture was refluxed for 1.5 hours
3. stirringStirring
4. waitwas continued overnight at room temperature
5. temperatureThereafter the mixture was heated
6. temperatureto reflux
7. additionwas added during 1.75 hours
8. temperatureby refluxing for 1.5 hours
9. stirringstirring at room temperature overnight
10. filtrationPrecipitated salts were filtered off
11. customAfter evaporation of CH3OH
12. extractionThe water phase was extracted three times with CH2Cl2
13. dry with materialThe combined CH2Cl2 phases were dried over Na2SO4
14. customevaporated
15. customdried