Phosphorus oxychloride → Ethyl 4-chloro-6-(2,4-dichlorophenyl)pyrazolo[1,5-a]pyrazine-2-carboxylate

HRID 57671Notes

Reaction equation

HRID 57671 reaction equation
[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]1[NH:10][C:11](=O)[C:12]2[N:13]([N:15]=[C:16]([C:18]([O:20][CH2:21][CH3:22])=[O:19])[CH:17]=2)[CH:14]=1.C(=O)(O)[O-].[Na+].P(Cl)(Cl)([Cl:31])=O>>[Cl:31][C:11]1[C:12]2[N:13]([N:15]=[C:16]([C:18]([O:20][CH2:21][CH3:22])=[O:19])[CH:17]=2)[CH:14]=[C:9]([C:3]2[CH:4]=[CH:5][C:6]([Cl:8])=[CH:7][C:2]=2[Cl:1])[N:10]=1

Participants

4

Reactant 3

HCID 24813Phosphorus oxychlorideHCID 516892Sodium Bicarbonate2×HCID 58170089Ethyl 6-(2,4-dichlorophenyl)-4-oxo-4,5-dihydropyrazolo[1,5-a]pyrazine-2-carboxylate

Product 1

HCID 58170012Ethyl 4-chloro-6-(2,4-dichlorophenyl)pyrazolo[1,5-a]pyrazine-2-carboxylate

Procedure

6.86 g (19.5 mmol) of ethyl 6-(2,4-dichlorophenyl)-4-oxo-4,5-dihydropyrazolo[1,5-a]pyrazine-2-carboxylate (Example 11A) were dissolved in 50 ml of phosphoryl chloride and stirred at reflux for 12 h. The reaction mixture was poured into 1.25 l of saturated sodium bicarbonate solution, and solid sodium bicarbonate was added until a pH of 7 had been reached. The solid was filtered off and dissolved in dichloromethane and chromatographed on silica gel (mobile phase cyclohexane/ethyl acetate 10:1). This gave 6.34 g (85% of theory) of the product as a solid.

Workup

  1. temperatureat reflux for 12 h
  2. additionwas added until a pH of 7
  3. filtrationThe solid was filtered off
  4. dissolutiondissolved in dichloromethane
  5. customchromatographed on silica gel (mobile phase cyclohexane/ethyl acetate 10:1)

Sources & evidence

ORD record
ord-1aac14a2d4774ed5af75ddb5850e5cf3
Source dataset
uspto-grants-2016_09
Patent number
US09434731B2

Reaction notes

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