反应详情

A solution of (E)-ethyl 4-ethoxy-3-(4-fluorophenyl)-2-oxobut-3-enoate (1.5 g, 5.63 mmol, 1.00 equiv) and hydroxylamine hydrochloride (2 g, 28.99 mmol, 5.15 equiv) in ethanol (10 mL) was refluxed for 3 h. The reaction mixture was cooled to room temperature and then quenched by 15 mL of saturated sodium bicarbonate solution. The resulting mixture was extracted with 2×10 mL of ethyl acetate. The combined organic layers was dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was purified on a silica gel column eluted with 0-10% of ethyl acetate in petroleum ether to yield 340 mg (26%) of ethyl 4-(4-fluorophenyl)-1,2-oxazole-5-carboxylate as a yellow oil. 1H-NMR (300 MHz, CDCl3): δ 8.57 (s, 1H), 7.47-7.43 (m, 2H), 7.11-7.03 (m, 2H), 4.43 (q, J=7.2 Hz, 2H), 1.30 (t, J=7.2 Hz, 3H) ppm.

1. customquenched by 15 mL of saturated sodium bicarbonate solution
2. extractionThe resulting mixture was extracted with 2×10 mL of ethyl acetate
3. dry with materialThe combined organic layers was dried over anhydrous sodium sulfate
4. concentrationconcentrated under vacuum
5. customThe residue was purified on a silica gel column
6. washeluted with 0-10% of ethyl acetate in petroleum ether