反应详情

A solution of N-bromosuccinimide (0.83 g, 4.7 mmol) in DMF (5 mL) was added dropwise to a stirred solution of ethyl 5-nitro-1H-indole-2-carboxylate (1.0 g, 4.27 mmol) in DMF (5 mL) at 0˜5° C. After the addition was completed, the reaction was warmed to room temperature and stirring was continued for an additional 1.5 h. The reaction mixture was poured over ice water and the resulting precipitate was collected and dried. The dried solid was re-dissolved in DMF (10 mL) and benzyl bromide (0.68 g, 4.0 mmol) and Cs2CO3 (6.56 g, 20 mmol) were added successively. The reaction was stirred for overnight and then diluted with water. The product was extracted with ethyl acetate, dried over magnesium sulfate. Recrystallization from ethyl acetate and hexane gave 0.99 g (57%) of ethyl 1-benzyl-3-bromo-5-nitro-1H-indole-2-carboxylate as an off-white solid: 1H NMR (DMSO-d6) δ 1.28 (t, J=7.0 Hz, 3H, 4.35 (q, J=7.0 Hz, 2H, 5.90 (s, 2H, 7.00-7.10 (m, 2H, 7.20-7.35 (m, 3H, 7.95 (d, J=9.3 Hz, 1H, 8.25 (dd, J=9.3, 2.0 Hz, 1H, 8.48 (d, J=2.0 Hz, 1H; MS (ESI) m/z 403/405 (MH+).

1. additionAfter the addition
2. customthe resulting precipitate was collected
3. customdried
4. dissolutionThe dried solid was re-dissolved in DMF (10 mL)
5. stirringThe reaction was stirred for overnight
6. extractionThe product was extracted with ethyl acetate
7. dry with materialdried over magnesium sulfate
8. customRecrystallization from ethyl acetate and hexane