Water → ethyl 3-phenyl-1H-pyrazole-1-acetate

HRID 477464Notes

Reaction equation

[H-].[Na+].[C:3]1([C:9]2[CH:13]=[CH:12][NH:11][N:10]=2)[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=1.Br[CH2:15][C:16]([O:18][CH2:19][CH3:20])=[O:17].O>CN(C=O)C>[C:3]1([C:9]2[CH:13]=[CH:12][N:11]([CH2:15][C:16]([O:18][CH2:19][CH3:20])=[O:17])[N:10]=2)[CH:4]=[CH:5][CH:6]=[CH:7][CH:8]=1

Participants

Conditions

Temperature: 100 °C

Procedure

To a slurry of 8g (0.2 mol) of sodium hydride in 100 mL of DMF at room temperature was added 23g (0.16 mol) of 3-phenylpyrazole. The mixture was stirred 1 hr and 17.8 mL (0.16 mol) of ethyl bromoacetate was added. The reaction was heated at about 100° C. for 2 hr, cooled, poured into water, extracted into methylene chloride, dried over magnesium sulfate and stripped. The resulting oil was chromatographed on silica gel HPLC using 25% ethyl acetate in hexane. The first, and major, component to elute was the 3-isomer. It was recrystallized from ether-hexane to yield 6.0g of ethyl 3-phenyl-1H-pyrazole-1-acetate having an Rf of 0.66 on silica gel in 1:1 ethylacetate-hexane. The third component to elute from the HPLC separation was a minor fraction containing the 5-isomer. Upon stripping the solvent one obtained 1.0g of ethyl 5-phenyl-1H-pyrazole-1-acetate as an oil having an Rf of 0.51 on silica gel in 1:1 ethyl acetate-hexane.

Workup

temperaturecooled
extractionextracted into methylene chloride
dry with materialdried over magnesium sulfate
customThe resulting oil was chromatographed on silica gel
washThe first, and major, component to elute
customIt was recrystallized from ether-hexane

Sources & evidence

ORD record: ord-10a4633b91c44dbd9d4fc26fbbb2f4f8
Source dataset: uspto-grants-1989_12
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04888352

Reaction notes

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