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

HRID 1631294Notes

Reaction equation

HRID 1631294 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 the 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 extracted with DCM. The combined organics were dried with MgSO4, filtered and concentrated to afford ethyl 5-chloropyrazolo[1,5-a]pyrimidine-3-carboxylate (24.2 g, 97.6% yield) as a pale yellow solid. 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 the 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 extracted with DCM
  11. dry with materialThe combined organics were dried with MgSO4
  12. filtrationfiltered
  13. concentrationconcentrated

Sources & evidence

ORD record
ord-6a5c1bdf4ef6439e85fe185602ab8d21
Source dataset
uspto-grants-2014_07
Patent number
US08791123B2

Reaction notes

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