反应详情

To a stirred mixture of 2-(1-aminoethyl)pyrazine (225 mg), ethanol (10 mL) and K2CO3 (72 mg) heated to reflux was added dropwise over 30 min, a solution of 4 g of 1,1-dimethyl-4-oxopiperidinium iodide (2.1 g) in water (36 mL). When the addition was complete, the mixture was heated under reflux for an additional 2 h, cooled, basified to pH 10 with Na2CO3 and extracted with ethyl acetate (3×100 mL). The combined organic extracts were dried over MgSO4 and concentrated under reduced pressure. Column chromatography over silica gel, eluting with a gradient of ethyl acetate; 0-5% methanol gave 300 mg of 1-(1-(2-pyrazinyl)-ethyl)-4-oxopiperidine as an oil: 1H NMR (400 MHz, CDCl3) 8.74 (d, 1H), 8.54 (dd, 1H), 8.48 (d, 1H), 3.94 (q, 1H), 2.89-2.75 (m, 4H), 2.46 (t, 4H), 1.50 (d, 3H).

1. temperatureheated
2. temperatureto reflux
3. additionwas added dropwise over 30 min
4. additionWhen the addition
5. temperaturethe mixture was heated
6. temperatureunder reflux for an additional 2 h
7. temperaturecooled
8. extractionextracted with ethyl acetate (3×100 mL)
9. dry with materialThe combined organic extracts were dried over MgSO4
10. concentrationconcentrated under reduced pressure
11. washColumn chromatography over silica gel, eluting with a gradient of ethyl acetate