反应详情

20 G. of 2,4-diamino-6-[3,6-dihydro-1(2H)-pyridyl]-pyrimidine-3-oxide are suspended and stirred in 140 ml. of methylene chloride and 120 ml. of water. While cooling, there are simultaneously added dropwise 8 ml. of chloroformic acid methyl ester in 20 ml. of methylene chloride and sufficient 28% sodium hydroxide so that the pH value is held between 7.0 and 7.5. After completion of the addition, the mixture is stirred for a further 1 hour and the residue is subsequently filtered off. The two phases obtained are separated and the organic phase is treated for 1 hour while stirring at 0° C. with 150 ml. of 1-N sodium hydroxide. The mixture obtained is treated with 20 ml. of methanol and the two phases are separated. The aqueous phase is extracted twice with 200 ml. of methylene chloride and the combined organic extracts are dried over sodium sulfate. By evaporation of the solvent there is obtained pure methyl 2-amino-6-[3,6-dihydro-1(2H)-pyridyl]-4-pyrimidinecarbamate-3-oxide having a melting point of 174°-176° C.

1. temperatureWhile cooling
2. additionthere are simultaneously added dropwise 8 ml
3. additionAfter completion of the addition
4. stirringthe mixture is stirred for a further 1 hour
5. filtrationthe residue is subsequently filtered off
6. customThe two phases obtained
7. customare separated
8. additionthe organic phase is treated for 1 hour
9. stirringwhile stirring at 0° C. with 150 ml
10. customThe mixture obtained
11. additionis treated with 20 ml
12. customof methanol and the two phases are separated
13. extractionThe aqueous phase is extracted twice with 200 ml
14. dry with materialof methylene chloride and the combined organic extracts are dried over sodium sulfate
15. customBy evaporation of the solvent there