p-Hydrazinobenzenesulphonamide → Enflicoxib

HRID 1611860Notes

Reaction equation

HRID 1611860 reaction equation
[O-]CC.[Na+].[F:5][C:6]([F:20])([F:19])[C:7](=O)[CH:8]=[CH:9][C:10]1[CH:15]=[CH:14][C:13]([F:16])=[CH:12][C:11]=1[F:17].[NH2:21][S:22]([C:25]1[CH:30]=[CH:29][C:28]([NH:31][NH2:32])=[CH:27][CH:26]=1)(=[O:24])=[O:23]>C(O)C>[NH2:21][S:22]([C:25]1[CH:26]=[CH:27][C:28]([N:31]2[CH:9]([C:10]3[CH:15]=[CH:14][C:13]([F:16])=[CH:12][C:11]=3[F:17])[CH2:8][C:7]([C:6]([F:20])([F:19])[F:5])=[N:32]2)=[CH:29][CH:30]=1)(=[O:24])=[O:23]

Participants

5

Reactant 3

HCID 78105p-HydrazinobenzenesulphonamideHCID 2723922Sodium ethoxideHCID 695335691,1,1-Trifluoro-4-(2,4-difluorophenyl)-3-butene-2-one

Product 1

HCID 9953093EnflicoxibYield 65%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

In a flask with an inert atmosphere sodium ethoxide (0.53 g, 7.72 mmoles) is dissolved in 45 ml of ethanol. 1,1,1-trifluoro-4-(2,4-difluorophenyl)-3-butene-2-one (prepared according to method E-1) (0.913 g, 3.86 mmoles) and 4-(aminosulphonyl)phenylhydrazine chlorohydrate (0.87 g, 3.87 mmoles) are added and the mixture was refluxed for 16 hours. The mixture was cooled, evaporated to dryness, cold water added, and the mixture acidified by adding acetic acid and the precipitated solid filtered. This solid was redissolved in ether, treated with active C, filtered and the solvent eliminated with a rotavapor. The resulting residue was crystallised from ethyl ether-petrol ether (50:50) to give 1-(4-aminosulphonylphenyl)-5-(2,4-difluorophenyl)-4,5-dihydro-3-trifluoromethyl-1H-pyrazole (1.02 g, yield: 65%) in the form of a solid m.p.=160-2° C.

Workup

  1. temperaturethe mixture was refluxed for 16 hours
  2. temperatureThe mixture was cooled
  3. customevaporated to dryness, cold water
  4. additionadded
  5. additionby adding acetic acid
  6. filtrationthe precipitated solid filtered
  7. dissolutionThis solid was redissolved in ether
  8. additiontreated with active C
  9. filtrationfiltered
  10. customThe resulting residue was crystallised from ethyl ether-petrol ether (50:50)

Sources & evidence

ORD record
ord-35b3b07460ee4250b3e32f0a0adbd8ca
Source dataset
uspto-grants-2006_01
Patent number
USRE038963E1

Reaction notes

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