Phosphorus oxychloride → 5-Chloropyrazolo(1,5-a)pyrimidine

HRID 538974Notes

Reaction equation

HRID 538974 reaction equation
[N:1]1[N:5]2[CH:6]=[CH:7][C:8](O)=[N:9][C:4]2=[CH:3][CH:2]=1.O=P(Cl)(Cl)[Cl:13]>>[Cl:13][C:8]1[CH:7]=[CH:6][N:5]2[N:1]=[CH:2][CH:3]=[C:4]2[N:9]=1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178516350HCID 178516350, compound

Product 1

HCID 210717595-Chloropyrazolo(1,5-a)pyrimidineYield 68%

Procedure

A mixture of pyrazolo[1,5-a]pyrimidin-5-ol (17.0 g, 126 mmol) in POCl3 (100 mL) was heated at reflux for 3 hours. After cooling, the reaction was concentrated under vacuum. To the residue was added dichloromethane. The organic phase was carefully washed with saturated aqueous NaHCO3 solution, dried and concentrated. The crude product was purified by passing through a short silica gel pad eluting with 50% EtOAc in hexane to give 5-chloropyrazolo[1,5-a]pyrimidine (13.1 g, 68%).

Workup

  1. temperaturewas heated
  2. temperatureat reflux for 3 hours
  3. temperatureAfter cooling
  4. concentrationthe reaction was concentrated under vacuum
  5. additionTo the residue was added dichloromethane
  6. washThe organic phase was carefully washed with saturated aqueous NaHCO3 solution
  7. customdried
  8. concentrationconcentrated
  9. customThe crude product was purified
  10. washeluting with 50% EtOAc in hexane

Sources & evidence

ORD record
ord-1c608ab7febf436eb1ab937fd567dee6
Source dataset
uspto-grants-2014_10
Patent number
US08865726B2

Reaction notes

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