Cyclopentylhydrazine hydrochloride → Cyclopentyl-5-trifluoromethyl-1H-pyrazole-4-carboxylic acid ethyl ester

HRID 12891

Reaction equation

Cl.[CH:2]1([NH:7][NH2:8])[CH2:6][CH2:5][CH2:4][CH2:3]1.[CH2:9]([O:11][C:12](=[O:24])[C:13](=[CH:20]N(C)C)[C:14](=O)[C:15]([F:18])([F:17])[F:16])[CH3:10].C([O-])(=O)C.[Na+]>C(O)C>[CH2:9]([O:11][C:12]([C:13]1[CH:20]=[N:8][N:7]([CH:2]2[CH2:6][CH2:5][CH2:4][CH2:3]2)[C:14]=1[C:15]([F:16])([F:17])[F:18])=[O:24])[CH3:10]

Participants

Conditions

Temperature: 70 °C

Procedure

Cyclopentyl-hydrazine hydrochloride (0.250 g, 1.83 mmol, Example 64, Step 2), 2-dimethylaminomethylene-4,4,4-trifluoro-3-oxo-butyric acid ethyl ester (0.403 g, 1.68 mmol) and anhydrous sodium acetate (0.163 g, 1.99 mmol) were combined in ethanol (2.5 mL) and heated at 70° C. for 17 hours. After cooling to room temperature, the reaction mixture was partitioned between methylene chloride and water. The organic phase was washed with water and brine. Each aqueous phase was back extracted with a second portion of methylene chloride. The two organic phases were combined, dried over sodium sulfate and concentrated in vacuo. Purification by flash chromatography, eluting with a 10-40% ethyl acetate-hexanes gradient, yielded 1-cyclopentyl-5-trifluoromethyl-1H-pyrazole-4-carboxylic acid ethyl ester (0.244 g, 52%). Mass spectrum: m/z: 277.1 (M+H).

Workup

temperatureAfter cooling to room temperature
customthe reaction mixture was partitioned between methylene chloride and water
washThe organic phase was washed with water and brine
extractionEach aqueous phase was back extracted with a second portion of methylene chloride
dry with materialdried over sodium sulfate
concentrationconcentrated in vacuo
customPurification by flash chromatography
washeluting with a 10-40% ethyl acetate-hexanes

Sources & evidence

ORD record: ord-c4b6d49295c04785a4247f88d64849e0
Source dataset: uspto-grants-2010_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07728029B2

Linked notes

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