反应详情

To the solution of N,N-2-trimethylprop-1-en-1-amine (I-49a, 240 mg, 2.42 mmol) in anhydrous Et2O (40 mL) at −78° C. was added dropwise Br2 (0.12 mL, 2.42 mmol), whereupon I-49b precipitated as a thick, light yellow solid. This mixture was then warmed and kept at 0° C., and treated dropwise with a −78° C. solution of t-butyl lithioacetate, which was prepared in situ by dropwise addition of tert-butyl acetate (I-49c, 0.65 mL, 4.84 mmol) to a solution of LDA at −78° C. (prepared by dropwise addition of n-BuLi (3.02 mL, 4.84 mmol) to diisopropylamine (0.65 mL, 4.84 mmol) in Et2O (10 mL) at −78° C.). During the addition, the precipitate dissolved, and a pale yellow solution was obtained. The reaction mixture was allowed to warm to room temperature, and stirred for another 1 h. The reaction mixture was partitioned between Et2O and water and extracted with Et2O. The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by column chromatography (0-10% MeOH in CH2Cl2) to afford (E)-tert-butyl 4-(dimethylamino)-4-methylpent-2-enoate (I-49d). MS calculated for C12H24NO2 (M+H+) 214.17. found: 214.2.

1. customwhereupon I-49b precipitated as a thick, light yellow solid
2. temperatureThis mixture was then warmed
3. customkept at 0° C.
4. additiontreated dropwise with a −78° C. solution of t-butyl lithioacetate, which
5. additionDuring the addition
6. dissolutionthe precipitate dissolved
7. customa pale yellow solution was obtained
8. customThe reaction mixture was partitioned between Et2O and water
9. extractionextracted with Et2O
10. dry with materialThe combined organic layers were dried over Na2SO4
11. concentrationconcentrated under reduced pressure
12. customThe crude material was purified by column chromatography (0-10% MeOH in CH2Cl2)