反应详情

To a suspension of 1-(hydroxyimino)ethylamine (7.4 g) in dry tetrahydrofuran (450 ml) was added sodium hydride (3.7 g, 60% in mineral oil) carefully. The mixture was stirred at room temperature for 15 minutes, and refluxed for 30 minutes. To this mixture was added 3,5-bis(methoxycarbonyl)pyridine (15 g), and the mixture was refluxed for 3 hours. After being cooled to room temperature, the reaction mixture was poured into a mixture of ethyl acetate (200 ml) and water (200 ml) under stirring. The aqueous layer was adjusted to pH 3.5 with 10% hydrochloric acid. The resulting precipitate was collected by filtration, washed with water and dried in vacuo to afford 5-(3-methyl-1,2,4-oxadiazol-5-yl)-3-pyridinecarboxylic acid (5.04 g).

1. temperaturerefluxed for 30 minutes
2. temperaturethe mixture was refluxed for 3 hours
3. temperatureAfter being cooled to room temperature
4. stirringunder stirring
5. filtrationThe resulting precipitate was collected by filtration
6. washwashed with water
7. customdried in vacuo