Pyridine → 3-Bromo-5-chloropyrazin-2-amine

2-Amino-5-chloropyrazine (1.7 g) was dissolved in chloroform (190 ml) and pyridine (1.3 ml) was added under an argon atmosphere. The flask and its contents were protected from light and a solution of bromine (0.7 ml) in chloroform (85 ml) was added over a period of 1 hour. After stirring for 2 hours more bromine (0.07 ml) in chloroform (8.5 ml) was added and, after stirring for 30 minutes, pyridine (0.2 ml) was added. The reaction mixture was stirred for a further 30 minutes then washed with water (50 ml) and the organic phase was separated. The solvent was removed by evaporation and the residue was purified by chromatography through a bed of silica (90 g), eluting with hexane (200 ml) followed by dichloromethane. Dichloromethane fractions containing the product were evaporated to give 2-amino-3-bromo-5-chloropyrazine (1.68 g); 1H NMR (d6DMSO): 6.94 (br s, 2H), 8.09 (s, 1H); mass spectrum (+ve CI): 208 (M+H)+.

1. additionwas added
2. stirringThe reaction mixture was stirred for a further 30 minutes
3. washthen washed with water (50 ml)
4. customthe organic phase was separated
5. customThe solvent was removed by evaporation
6. customthe residue was purified by chromatography through a bed of silica (90 g)
7. washeluting with hexane (200 ml)
8. additionDichloromethane fractions containing the product
9. customwere evaporated

ORD record

ord-dee2c821c34d453ead65318fe06f204a

Source dataset

uspto-grants-1997_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05668137