反应详情

温度

-78 °C

A solution of 1-(1,1-dimethylethyl) 4-ethyl 1,4-piperidinedicarboxylate (12.85 g, 50 mmol) in tetrahydrofuran (50 mL) was added slowly to a stirred, cooled (−78° C.) solution of potassium hexamethyldisilazide (14.96 g, 75 mmol) in tetrahydrofuran (75 mL), maintaining the internal temperature below −65° C. The mixture was stirred at −78° C. for 30 minutes, then 3-bromo-2-methylpropene (7.56 mL, 10.12 g, 75 mmol) was added dropwise over 5 minutes. The mixture was stirred at −78° C. for 1 hour, then saturated aqueous ammonium chloride (200 mL) was added and the mixture was warmed to room temperature. Water (100 mL) was added and the mixture was extracted with ethyl acetate (3×200 mL). The combined organic fractions were washed with aqueous citric acid (10%, 3×200 mL), saturated aqueous sodium hydrogen carbonate (200 mL) and brine (200 mL), dried (MgSO4) and the solvent was evaporated under reduced pressure to give the title compound as a pale yellow oil (15.48 g, 99%). m/z (ES+) 256 (M+1-C4H8).

1. temperaturemaintaining the internal temperature below −65° C
2. stirringThe mixture was stirred at −78° C. for 1 hour
3. temperaturethe mixture was warmed to room temperature
4. extractionthe mixture was extracted with ethyl acetate (3×200 mL)
5. washThe combined organic fractions were washed with aqueous citric acid (10%, 3×200 mL), saturated aqueous sodium hydrogen carbonate (200 mL) and brine (200 mL)
6. dry with materialdried (MgSO4)
7. customthe solvent was evaporated under reduced pressure