Water → 5-Bromo-3-chloro-2-ethylquinoxaline

Temperature

-78 °C

LDA(Aldrich) (1.7M in heptane/THF/ethylbenzene; 0.60 mL, 1.01 mmol) was added (dropwise, over 1 min) to a solution of 5-bromo-3-chloro-2-methylquinoxaline (126e) (238 mg, 0.92 mmol) in THF (8.0 mL) in an oven-dried flask under argon at −78° C., and the resulting solution was stirred at −78° C. for 7 min. Methyl iodide (0.12 mL, 1.85 mmol) was then added, and the resulting solution was stirred at −78° C. for 15 min, then warmed to 23° C. and stir at 23° C. for 16 h. The reaction mixture was subsequently cooled to 0° C., water (0.5 mL) was added, and the reaction mixture was concentrated onto silica gel and chromatographically purified (silica gel, 0-15% EtOAc/hexanes) to provide 5-bromo-3-chloro-2-ethylquinoxaline (136 mg, 0.50 mmol, 54% yield) as a light-orange solid. 1H NMR (400 MHz, CDCl3) δ ppm 8.04 (1H, d, J=3.1 Hz), 8.02 (1H, d, J=2.3 Hz), 7.60 (1H, t, J=8.0 Hz), 3.20 (2H, q, J=7.4 Hz), 1.44 (3H, t, J=7.4 Hz). m/z (ESI, +ve) 271.0/272.9 (M+H)+.

1. stirringthe resulting solution was stirred at −78° C. for 15 min
2. temperaturewarmed to 23° C.
3. stirringstir at 23° C. for 16 h
4. temperatureThe reaction mixture was subsequently cooled to 0° C.
5. concentrationthe reaction mixture was concentrated onto silica gel
6. customchromatographically purified (silica gel, 0-15% EtOAc/hexanes)

ORD record

ord-508a41c47d7a41008c0ced0153a43fe7

Source dataset

uspto-grants-2016_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09394297B2