反应详情

A mixture of 1.445 g (10 mmol) of 2-hydrazino-5-chloropyridine and ethyl trifluoroacetoacetate (1.5 ml; 10 mmol) in 5 ml of acetic acid was refluxed overnight with stirring under nitrogen and then cooled. The mixture was concentrated in vacuo, the residue was diluted with ethyl acetate, and the solid mixture was filtered. The filtrate was washed with saturated sodium bicarbonate solution, the aqueous layer was extracted with ethyl acetate, and the combined organic layer was dried over magnesium sulfate. The organic layer was concentrated in vacuo, the residue was purified by flash chromatography (ethyl acetate) and crystallized (from ethyl acetate/hexane followed by hexane) to afford 1.42 g of 1-(5-chloro-2-pyridyl)-3-trifluoromethyl-5-hydroxy-pyrazole as a white solid, m.p. 58°-59° C.

1. temperaturewas refluxed overnight
2. temperaturecooled
3. concentrationThe mixture was concentrated in vacuo
4. additionthe residue was diluted with ethyl acetate
5. filtrationthe solid mixture was filtered
6. washThe filtrate was washed with saturated sodium bicarbonate solution
7. extractionthe aqueous layer was extracted with ethyl acetate
8. dry with materialthe combined organic layer was dried over magnesium sulfate
9. concentrationThe organic layer was concentrated in vacuo
10. customthe residue was purified by flash chromatography (ethyl acetate)
11. customcrystallized (from ethyl acetate/hexane followed by hexane)