反应详情

2-(4-fluorophenyl)acetyl chloride (0.518 mL; 3.78 mmol) was added to a mixture of ethyl 2-amino-2-(hydroxyimino)acetate (0.5 g; 3.78 mmol) and N,N diisopropylethylamine (1.05 mL; 6.06 mmol) in dichloromethane (15 mL) at −15° C. The reaction mixture was stirred at room temperature overnight and poured into a mixture of ice and water. The formed precipitate was filtered off, suspended in pyridine (18 mL) and refluxed in a sealed tube for 20 h and concentrated under reduced pressure. The crude material was purified by flash chromatography on silica (eluent 20 to 100% ethyl acetate in heptane) to yield 0.315 g (33%) of ethyl 5-(4-fluorobenzyl)-1,2,4-oxadiazole-3-carboxylate as a white solid.

1. filtrationThe formed precipitate was filtered off
2. temperaturerefluxed in a sealed tube for 20 h
3. concentrationconcentrated under reduced pressure
4. customThe crude material was purified by flash chromatography on silica (eluent 20 to 100% ethyl acetate in heptane)