Phosphorus oxychloride → Ethyl 5-chloropyrazolo(1,5-a)pyrimidine-3-carboxylate

HRID 1426890Notes

Reaction equation

HRID 1426890 reaction equation
O[C:2]1[CH:7]=[CH:6][N:5]2[N:8]=[CH:9][C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:4]2[N:3]=1.P(Cl)(Cl)([Cl:18])=O>>[Cl:18][C:2]1[CH:7]=[CH:6][N:5]2[N:8]=[CH:9][C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:4]2[N:3]=1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178469952HCID 178469952, compound

Product 1

HCID 58063474Ethyl 5-chloropyrazolo(1,5-a)pyrimidine-3-carboxylateYield 97.6%

Procedure

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).

Workup

  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

Sources & evidence

ORD record
ord-f0423c0b570e496c9abe658ed58ec180
Source dataset
uspto-grants-2015_01
Patent number
US08933084B2

Reaction notes

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