Nitric Acid → [3,5-Dimethyl-1-(4-nitro-benzyl)-1H-pyrazol-4-yl]-acetic acid methyl ester

HRID 1631900Notes

Reaction equation

[CH3:1][O:2][C:3](=[O:19])[CH2:4][C:5]1[C:6]([CH3:18])=[N:7][N:8]([CH2:11][C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)[C:9]=1[CH3:10].[N+:20]([O-])([OH:22])=[O:21]>OS(O)(=O)=O>[CH3:1][O:2][C:3](=[O:19])[CH2:4][C:5]1[C:6]([CH3:18])=[N:7][N:8]([CH2:11][C:12]2[CH:17]=[CH:16][C:15]([N+:20]([O-:22])=[O:21])=[CH:14][CH:13]=2)[C:9]=1[CH3:10]

Participants

Conditions

Temperature: -7 °C

Procedure

Under cooling, (1-benzyl-3,5-dimethyl-1H-pyrazol-4-yl)-acetic acid methyl ester (intermediate 1.1.1, 3.10 g, 12.0 mmol) was dissolved in conc. H2SO4 (7 mL). The mixture was cooled to −7° C. and HNO3 (65%, 0.77 mL) was added dropwise under stirring, keeping the temperature below 0° C. The reaction mixture was allowed to come to room temperature and stirred for 20 min at room temperature. The reaction mixture was poured into ice water, extracted with dichloromethane and the organic layer was concentrated under reduced pressure. The resulting product is a mixture of regioisomers, with the 4-nitro isomer as the main product.

Workup

temperatureUnder cooling
customthe temperature below 0° C
customto come to room temperature
stirringstirred for 20 min at room temperature
extractionextracted with dichloromethane
concentrationthe organic layer was concentrated under reduced pressure
additiona mixture of regioisomers

Sources & evidence

ORD record: ord-b3be152d0a7d4f8aa8290e3407788846
Source dataset: uspto-grants-2014_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08791272B2

Reaction notes

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