Phosphorus oxychloride → 2-(1-Bromoethyl)-3-chloro-6-fluoroquinoxaline

Temperature

100 °C

A heterogeneous mixture of 3-(1-bromoethyl)-7-fluoroquinoxalin-2(1H)-one (58.86 g, 217.1 mmol) and phosphorous oxychloride (198.8 ml, 2171 mmol) in a 1 L round bottom flask was stirred at 100° C. for 2 h. The mixture was heterogeneous in the beginning of the reaction and then homogeneous black solution over 1 h. After 2 h, the mixture was cooled to rt and concentrated under reduced pressure. To the black residue was carefully added ice (˜400 ml) in portions and then water (200 ml) with stirring. The mixture was neutralized with NH4OH (200 ml) and ice (˜200 ml) with stirring. The resulting precipitate was collected by filtration, rinsed with water (1 L), and dried under high vacuum overnight to give 2-(1-bromoethyl)-3-chloro-6-fluoroquinoxaline (58.31 g, 92.8% yield) including 3-chloro-2-(1-chloroethyl)-6-fluoroquinoxaline as a brown solid. 1H NMR (400 MHz, DMSO-d6), ratio of bromoethyl analog and chloroethyl analog=2.5:1 Mass Spectrum (ESI) m/e=288.9 [M+H(79Br)]+ and 291.0 [M+H (81Br)]+

1. customThe mixture was heterogeneous in the beginning of the reaction
2. waithomogeneous black solution over 1 h
3. waitAfter 2 h
4. temperaturethe mixture was cooled to rt
5. concentrationconcentrated under reduced pressure
6. stirringwater (200 ml) with stirring
7. stirringwith stirring
8. filtrationThe resulting precipitate was collected by filtration
9. washrinsed with water (1 L)
10. customdried under high vacuum overnight

ORD record

ord-86e02f9c3a284b659a42addacb36b686

Source dataset

uspto-grants-2014_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08716290B2