反应详情

Sodium borohydride (19 g, 0.5 mole) is added portionwise to an isopropanol (1 liter) solution of 1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate (40.1 g, 0.25 mole). The reaction is allowed to stir at room temperature for 3 days; then additional sodium borohydride (9 g, 0.25 mole) is added, and the reaction is heated to reflux with stirring and maintained there for 7 hours. The reaction mixture is cooled to room temperature and water (100 ml) is added over a 11/2-hour period. After stirring for 2 hours, the isopropanol is removed on a rotary evaporator, and the resulting paste slurried in water and extracted with diethyl ether. Evaporation of the ether layer gives the pyrazolidine as a viscous oil; 48.3 g, 72%, and analyzed as its HCl salt.

1. temperaturethe reaction is heated
2. temperatureto reflux
3. stirringwith stirring
4. temperaturemaintained there for 7 hours
5. temperatureThe reaction mixture is cooled to room temperature
6. stirringAfter stirring for 2 hours
7. customthe isopropanol is removed on a rotary evaporator
8. extractionextracted with diethyl ether
9. customEvaporation of the ether layer