反应详情

A suspension of ethyl 5-amino-1-(2-pyridinyl)-1H-pyrazole-4-carboxylate (27.9 g, 120 mmol) in 4N sodium hydroxide (300 mL) was heated under reflux for 1 hour. The suspension was allowed to cool to room temperature, neutralized by the addition of conc. hydrochloric acid, and further made acidic by the addition of acetic acid. The resulting crystals were collected by filtration, washed with ethanol, and air dried. The crystals thus obtained were subjected to heat at 200° C., and washed with diethylether to give the title compound (6.02 g, 31% yield). NMR (CDCl3) δ: 5.51 (1H, d, J=1.8 Hz), 5.95 (2H, br s), 7.07-7.13 (1H, m), 7.42 (1H, d, J=1.8 Hz), 7.75-7.84 (1H, m), 7.98 (1H, d, J=8.4 Hz), 8.33 (1H, dd, J=1.6 Hz, 4.6 Hz).

1. temperaturewas heated
2. temperatureunder reflux for 1 hour
3. filtrationThe resulting crystals were collected by filtration
4. washwashed with ethanol, and air
5. customdried
6. customThe crystals thus obtained
7. temperatureto heat at 200° C.
8. washwashed with diethylether