反应详情

Ethyl 5-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (22.7 g, 110 mmol) was suspended in phosphoryl trichloride (100 mL) and heated to reflux. After heating for 2 hours, the reaction mixture was cooled and concentrated to remove excess POCl3. The residue was diluted in DCM (100 mL) and slowly added to a flask containing ice water. The mixture was separated and the aqueous layer was extracted with DCM (2×200 mL). The combined organic layers were dried (MgSO4), filtered and concentrated to afford ethyl 5-chloropyrazolo[1,5-a]pyrimidine-3-carboxylate as a pale-yellow solid (24.2 g, 97.6% yield). MS (apci) m/z=225.9 (M+H).

1. temperatureheated to reflux
2. temperatureAfter heating for 2 hours
3. temperaturethe reaction mixture was cooled
4. concentrationconcentrated
5. customto remove excess POCl3
6. additionThe residue was diluted in DCM (100 mL)
7. additionslowly added to a flask
8. additioncontaining ice water
9. customThe mixture was separated
10. extractionthe aqueous layer was extracted with DCM (2×200 mL)
11. dry with materialThe combined organic layers were dried (MgSO4)
12. filtrationfiltered
13. concentrationconcentrated