反应详情

温度

0 °C

A solution of 4-chloromethyl-5-methyl-3-(4-trifluoromethylphenyl)isoxazole (1.37 g) in tetrahydrofuran (50 ml) was added to a mixture of diethyl malonate (1.20 g), sodium hydride (60%, oil, 0.21 g) and tetrahydrofuran (20 ml) at 0° C. The mixture was stirred at 0° C. for 1 hr and then at room temperature overnight. The reaction mixture was acidified with dilute hydrochloric acid and extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4) and concentrated. The residue was subjected to silica gel column chromatography, and a colorless oil was obtained from a fraction eluted with ethyl acetate-hexane (1:3, volume ratio). A mixture of the obtained colorless oil, 6N hydrochloric acid (30 ml) and acetic acid (30 ml) was refluxed for 5 hr. The reaction mixture was concentrated, and water was added to the residue. The obtained colorless crystals were filtrated to give 3-[5-methyl-3-(4-trifluoromethylphenyl)-4-isoxazolyl]propionic acid (1.25 g, yield 84%). The crystals were recrystallized from ethanol-hexane. melting point: 138–139° C.

1. customat room temperature
2. customovernight
3. extractionextracted with ethyl acetate
4. washThe ethyl acetate layer was washed with saturated brine
5. dry with materialdried (MgSO4)
6. concentrationconcentrated
7. customa colorless oil was obtained from a fraction
8. washeluted with ethyl acetate-hexane (1:3, volume ratio)
9. additionA mixture of the obtained colorless oil, 6N hydrochloric acid (30 ml) and acetic acid (30 ml)
10. temperaturewas refluxed for 5 hr
11. concentrationThe reaction mixture was concentrated
12. additionwater was added to the residue
13. filtrationThe obtained colorless crystals were filtrated