Phosphorus oxychloride → 3H-Pyrazol-3-one, 2,4-dihydro-2,5-diphenyl-

HRID 1289850Notes

Reaction equation

HRID 1289850 reaction equation
[C:1]1([N:7]2[C:11](=[O:12])[CH2:10][C:9]([OH:13])=[N:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.O=P(Cl)(Cl)[Cl:16]>C(=O)(O)[O-].[Na+]>[C:1]1([N:7]2[C:11](=[O:12])[CH2:10][C:9]([C:1]3[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=3)=[N:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[C:1]1([N:7]2[C:11]([Cl:16])=[CH:10][C:9]([OH:13])=[N:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1

Participants

5

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178516658HCID 178516658, compound

Product 2

HCID 785593H-Pyrazol-3-one, 2,4-dihydro-2,5-diphenyl-HCID 178516191HCID 178516191, compound

Reagents, catalysts & solvents 1

HCID 516892Sodium BicarbonateSolvent

Conditions

Temperature
100 °C

Procedure

A mixture of 2,4-dihydro-2-phenyl-5-hydroxy-3H-pyrazol-3-one (1 g, 5.7 mmol) and POCl3 (1 g, 6.5 mmol) was heated at 100° C. for 4 hours and cooled. The mixture was diluted with ice/water and sodium bicarbonate solution was added (to pH=7). The aqueous layer was extracted with methylene chloride (3×), the organic layer was concentrated in vacuo, and the solid was crystallized from methylene chloride and recrystallized from acetonitrile and methylene chloride. The above solid was purified by column chromatography (silica gel, 6-33% ethyl acetate/hexane) to afford 110 mg of 2,4-dihydro-2-phenyl-5-chloro-3H-pyrazol-3-one (Formula III: R1 =Ph; R2 =Cl; R3 =H) and 56 mg of 1-phenyl-3-hydroxy-5-chloropyrazole as a white solid.

Workup

  1. temperaturecooled
  2. additionwas added (to pH=7)
  3. extractionThe aqueous layer was extracted with methylene chloride (3×)
  4. concentrationthe organic layer was concentrated in vacuo
  5. customthe solid was crystallized from methylene chloride
  6. customrecrystallized from acetonitrile and methylene chloride
  7. customThe above solid was purified by column chromatography (silica gel, 6-33% ethyl acetate/hexane)

Sources & evidence

ORD record
ord-100571b489cf487da756fe6eb3493a67
Source dataset
uspto-grants-1998_05
Patent number
US05750550

Reaction notes

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