反应详情

温度

70 °C

To a mixture of (S)-1-tert-butyl 2-methyl 4-methylenepyrrolidine-1,2-dicarboxylate (6 g, 24.9 mmol) and tetrabutylammonium bromide (161 mg, 0.02 eq) in anhydrous 1,2-dichloroethane (60 mL, 10 volumes) was added sodium tribromoacetate (17.48 g, 2.2 eq). The mixture was degassed and filled with N2 gas. It was heated at 70° C. for 2.5 hrs before additional sodium tribromoacetate (2.4 g, 0.3 eq) was added. The mixture was heated at 70° C. for 40 min. After the completion of the reaction, it was allowed to cool to room temperature and evaporated. The residue was diluted with 30% hexanes in tert-butyl methyl ether (100 mL) and filtered through a pad of celite. The filtrate was washed with water and brine, dried (Na2SO4), filtered and evaporated to dryness. The residue was passed through a silica gel (5.5 wt. volumes) pad with 0-15% tert-butyl methyl ether in hexanes and concentrated to afford the title compound (9.09 g, 88%) as a yellow oil as a mixture of two regioisomers. 1H NMR (500 MHz, CDCl3): 4.63-4.44 (m, 1H), 3.92-3.86 (m, 1H), 3.79 and 3.74 (2 s, 3H), 3.53-3.42 (m, 1H), 2.83-2.35 (m, 1.5H), 1.91-1.70 (m, 2.5H), 1.48 and 1.43 (2 s, 9H). ESI MS m/z (M+H)+ 413.85.

1. customThe mixture was degassed
2. additionfilled with N2 gas
3. additionwas added
4. customAfter the completion of the reaction, it
5. temperatureto cool to room temperature
6. customevaporated
7. additionThe residue was diluted with 30% hexanes in tert-butyl methyl ether (100 mL)
8. filtrationfiltered through a pad of celite
9. washThe filtrate was washed with water and brine
10. dry with materialdried (Na2SO4)
11. filtrationfiltered
12. customevaporated to dryness
13. concentrationconcentrated