反应详情

温度

-78 °C

In a 3-neck 3-liter round bottom flask equipped with two addition funnels is dissolved lepidine (10.0 mL, 75.63 mmol) in tetrahydrofuran (200 mL). One addition funnel is charged with ethyl picolinate (20.43 mL, 151.26 mmol) and the other with 0.5 M potassium bis(trimethylsilyl)amide (166.4 mL, 83.19 mmol) in toluene. The solution is cooled to −78° C. and the base added to the reaction mixture dropwise over 40 min. The reaction mixture is stirred an additional 1.5 h and ethyl picolinate is added rapidly. The ice bath is removed and the reaction mixture stirred at ambient temperature for 3 h. The reaction is quenched with water (20 mL) and after 5 min formic acid added until the pH is slightly less than 7. The mixture is concentrated in vacuo and partitioned between ethyl acetate (300 mL) and brine-sodium bicarbonate (300 mL) mixture. The organic layer is washed with brine and sodium bicarbonate, dried over sodium sulfate, and concentrated. The product is chromatographed on SiO2 (27-30% acetone in hexane) to yield 15.31 g (82%) of a yellow-brown solid.

1. customIn a 3-neck 3-liter round bottom flask equipped with two addition funnels
2. additionOne addition funnel
3. additionthe base added to the reaction mixture dropwise over 40 min
4. customThe ice bath is removed
5. stirringthe reaction mixture stirred at ambient temperature for 3 h
6. customThe reaction is quenched with water (20 mL) and after 5 min formic acid
7. additionadded until the pH
8. concentrationThe mixture is concentrated in vacuo
9. custompartitioned between ethyl acetate (300 mL) and brine-sodium bicarbonate (300 mL) mixture
10. washThe organic layer is washed with brine and sodium bicarbonate
11. dry with materialdried over sodium sulfate
12. concentrationconcentrated
13. customThe product is chromatographed on SiO2 (27-30% acetone in hexane)