反应详情

In an analogous manner to that described in J. Org. Chem. 50 (13) 1985, 2372-2375, 7.6 g (32.72 mmol) of ethyl 5-amino-4-phenyl-3-isoxazolecarboxylate in 160 ml of glacial acetic acid, 50 ml of water and 80 ml of tetrahydrofuran were treated portionwise at 15°-20° while stirring within 1 hour with a total of 22.6 g of sodium nitrite. The reaction mixture was thereafter poured into 1 liter of water and extracted 3 times with 400 ml of methylene chloride each time. The organic phases were combined and first washed twice with 1 liter of saturated sodium bicarbonate solution each time and then once with 1 liter of water, dried, filtered and concentrated in a vacuum, whereby after chromatography on silica gel and elution with methylene chloride there were obtained 3.9 g (55%) of ethyl 4-phenyl-3-isoxazolecarboxylate as a yellow oil which was used without further purification.

1. extractionextracted 3 times with 400 ml of methylene chloride each time
2. washfirst washed twice with 1 liter of saturated sodium bicarbonate solution each time
3. dry with materialonce with 1 liter of water, dried
4. filtrationfiltered
5. concentrationconcentrated in a vacuum, whereby after chromatography
6. washon silica gel and elution with methylene chloride