反应详情

Sodium bicarbonate (3.9 g, 46.2 mmol) is added in small portions to a mixture of ethyl 3-ethoxy-3-iminopropanoate hydrochloride (Z-1) (8.6 g, 44.0 mmol) in crushed ice (100 g) and ethyl acetate (50 mL) until the pH value reaches 8-9. The organic layer is separated and the aqueous layer was extracted with ethyl acetate (2×50 mL). The combined organic layers are dried over anhydrous MgSO4 and filtered. The filtrate is concentrated in vacuo to afford a colourless oil which is added to a solution of 1H-pyrazol-5-amine (3.65 g, 44.0 mmol) in ethanol (100 mL). The resulting mixture is then degassed and backfilled with argon (three cycles) and stirred at reflux overnight. The mixture is then filtered while it was still warm. The solid is rinsed with cold ethanol (25 mL) and ether (2×25 mL), and then dried in vacuo to afford 5-aminopyrazolo[1,5-a]pyrimidin-7(4H)-one (Z-2).

1. customThe organic layer is separated
2. extractionthe aqueous layer was extracted with ethyl acetate (2×50 mL)
3. dry with materialThe combined organic layers are dried over anhydrous MgSO4
4. filtrationfiltered
5. concentrationThe filtrate is concentrated in vacuo
6. customto afford a colourless oil which
7. customThe resulting mixture is then degassed
8. temperatureat reflux overnight
9. filtrationThe mixture is then filtered while it
10. temperaturewas still warm
11. washThe solid is rinsed with cold ethanol (25 mL) and ether (2×25 mL)
12. customdried in vacuo