反应详情

5 G. of dimethyl 6-piperidino-2,4-pyrimidine-dicarbamate-3-oxide are dissolved in 200 ml. of methylene chloride and mixed with 100 ml. of water. While stirring vigorously, the mixture is adjusted with concentrated sodium hydroxide to pH 12.5 and stirred at this pH for 3 hours. The two phases are separated and the aqueous phase is adjusted to pH 4 with concentrated hydrochloric acid. The resulting white precipitate is filtered off, washed with water, pre-dried slightly and recrystallized from a mixture of methylene chloride and methanol, there being obtained pure methyl 5-piperidino-2-oxo-2H-[1,2,4]oxadiazolo[2,3-a]pyrimidine-7-carbamate, having a melting point of 210°-214° C. (decomposition).

1. stirringstirred at this pH for 3 hours
2. customThe two phases are separated
3. filtrationThe resulting white precipitate is filtered off
4. washwashed with water
5. custompre-dried slightly
6. customrecrystallized from a mixture of methylene chloride and methanol, there