反应详情

(400 mg, 2.0 mmol) 1-Benzotriazol-1-yl-3-methyl-but-2-en-1-one (Example 1, step 1), (5-bromo-pyridin-2-yl)-hydrazine (410 mg, 2.2 mmol, 1.1 equiv.) and Et3N (1.95 ml, 14.0 mmol, 7 equiv.) were dissolved together in THF (2 ml) and stirred for 90 minutes at reflux temperature. The reaction mixture was cooled and extracted with saturated Na2CO3 solution and two times with ethyl acetate. The organic extracts were extracted with brine, dried over sodium sulfate and evaporated to dryness. The crude product was purified by flash chromatography on a silica gel column eluting with an ethyl acetate:cyclohexane gradient 0:100 to 50:50. The desired 2-(5-bromo-pyridin-2-yl)-5,5-dimethyl-pyrazolidin-3-one (230 mg, 43% yield) was obtained as a yellow oil, MS: m/e=270.2/272.2 (M+H+).

1. temperatureat reflux temperature
2. temperatureThe reaction mixture was cooled
3. extractionextracted with saturated Na2CO3 solution and two times with ethyl acetate
4. extractionThe organic extracts were extracted with brine
5. dry with materialdried over sodium sulfate
6. customevaporated to dryness
7. customThe crude product was purified by flash chromatography on a silica gel column
8. washeluting with an ethyl acetate