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

Participants

Reaction Steps

2-Amino-5-chloropyrazine (1.7 g) was dissolved in chloroform (190 ml) and pyridine (1.3 ml) was added under an argon atomosphere. 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. 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. Volatile material was removed by evaporation and 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 (d6 -DMSO): 6.94 (br s, 2H), 8.09 (s, 1H); mass spectrum (+ve CI): 208 (M+H)+.

Provenance & Evidence