反应详情

温度

0 °C

To a solution of diisopropylamine (7.5 mL, 0.11 mol) in THF (35 mL) at 0° C. was added n-BuLi (21 mL, 0.055 mol) dropwise. The mixture was stirred at 0° C. for 40 minutes. Then the mixture was cooled to −78° C. Tert-butyl 4-fluoro-1H-indole-1-carboxylate (5 g, 0.02 mol) in THF (13 mL) was added dropwise slowly. After addition, the mixture was stirred at −78° C. for 2 hours. Then triisopropyl borate (3.29 g, 0.03 mol) was added. The mixture was stirred at −78° C. for another 40 minutes. The reaction was monitored using TLC. When the reaction was completed, the mixture was adjusted to pH=6 with 1 N HCl. After extracted with EtOAc (25 mL×3), the combined organic layers were washed with brine (50 mL), dried over Na2SO4, filtered and concentrated in vacuo. The obtained solid was recrystallized with EtOAc and petroleum ether to provide (1-(tert-butoxycarbonyl)-4-fluoro-1H-indol-2-yl)boronic acid (4.5 g, yield: 76.7%, which might be unstable at high temp. work up, store in fridge). 1H-NMR (CDCl3, 400 MHz) δ 7.77 (d, J=8.4 Hz, 1H), 7.57 (s, 1H), 7.44 (s, 2H), 7.24 (m, 1H), 6.90 (m, 1H), 1.66 (s, 9H). MS (M+H)+: 280.

1. temperatureThen the mixture was cooled to −78° C
2. additionAfter addition
3. stirringthe mixture was stirred at −78° C. for 2 hours
4. stirringThe mixture was stirred at −78° C. for another 40 minutes
5. extractionAfter extracted with EtOAc (25 mL×3)
6. washthe combined organic layers were washed with brine (50 mL)
7. dry with materialdried over Na2SO4
8. filtrationfiltered
9. concentrationconcentrated in vacuo
10. customThe obtained solid was recrystallized with EtOAc and petroleum ether