反应详情

温度

0 °C

TBSOTf (2.92 mL, 12.73 mmol) was added (dropwise, over 3 min) to a mixture 1-(3-fluoro-2-methylquinoxalin-5-yl)ethanone (2.00 g, 9.79 mmol) and TEA (2.05 mL, 14.7 mmol) in DCM (100 mL) at 0° C., and the resulting solution was stirred at 0° C. for 30 min. The mixture was diluted with DCM (50 mL), washed with saturated aq. NaHCO3 (2×100 mL), dried over Na2SO4, filtered, and concentrated in vacuo to provide 5-(1-((tert-butyldimethylsilyl)oxy)vinyl)-3-fluoro-2-methylquinoxaline (3.451 g) as an orange-brown oil. This oil was taken up in THF (100 mL) and cooled to 0° C., water (2.82 mL, 157 mmol) and NBS (1.743 g, 9.79 mmol) were sequentially added, and the resulting solution was stirred at 0° C. for 2 min. The mixture was diluted with Et2O (100 mL) and sequentially washed with water (80 mL), saturated aq. NaHCO3 (80 mL), water (80 mL), and brine (80 mL). The resulting solution was dried over Na2SO4, filtered, and concentrated onto silica gel. Chromatographic purification (silica gel, 0-20% EtOAc/hexanes) provided 2-bromo-1-(3-fluoro-2-methylquinoxalin-5-yl)ethanone (2.77 g, 9.78 mmol, 100% yield) as a yellow solid: 1H NMR (400 MHz, CDCl3) δ ppm 8.27 (1H, d, J=5.3 Hz), 8.25 (1H, d, J=4.3 Hz), 7.82 (1H, t, J=7.8 Hz), 5.02 (2H, s), 2.80 (3H, d, J=1.4 Hz). 19F NMR (376 MHz, CDCl3) δ ppm −69.34 (1F, s). m/z (ESI, +ve) 283.0 (M+H)+.

1. washwashed with saturated aq. NaHCO3 (2×100 mL)
2. dry with materialdried over Na2SO4
3. filtrationfiltered
4. concentrationconcentrated in vacuo