Sulfuric Acid → 1-[(4-Methoxy)phenyl]-5-(methoxycarbonyl)pyrazole-3-carboxylic acid

HRID 394798Notes

Reaction equation

[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([N:9]2[C:13]([C:14]([O:16][CH3:17])=[O:15])=[CH:12][C:11]([C:18]([O:20]C)=[O:19])=[N:10]2)=[CH:5][CH:4]=1.S(=O)(=O)(O)O.C(=O)([O-])[O-].[K+].[K+]>O1CCOCC1.O>[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([N:9]2[C:13]([C:14]([O:16][CH3:17])=[O:15])=[CH:12][C:11]([C:18]([OH:20])=[O:19])=[N:10]2)=[CH:5][CH:4]=1

Participants

Conditions

Temperature: 100 °C

Procedure

To a solution of dimethyl 1-[(4-methoxy)phenyl]pyrazole-3,5-dicarboxylate (32.7 g, 110 mmol) in 50 mL of dioxane and 100 mL of water was added concentrated sulfuric acid (1.50 mL, 28.2 mmol). The resulting solution was stirred at 100° C. for 18 h and then cooled to room temperature. The reaction was made basic with potassium carbonate and then extracted with ether to remove unreacted diester. The aqueous layer was acidified with HCl and was extracted twice with ethyl acetate. The combined organics were washed with brine, dried (MgSO4) and concentrated to afford 19.2 g (63%) of the title compound along with 5.0 g (15%) of unreacted starting material. The title compound was used without further purification. LRMS (ES−): 274.9 (M−H)−.

Workup

temperaturecooled to room temperature
extractionextracted with ether
customto remove unreacted diester
extractionwas extracted twice with ethyl acetate
washThe combined organics were washed with brine
dry with materialdried (MgSO4)
concentrationconcentrated

Sources & evidence

ORD record: ord-ab0e90bf02294cca9bf5cd205560ac8d
Source dataset: uspto-grants-2003_08
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06602895B2

Reaction notes

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