反应详情

温度

100 °C

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.

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