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General procedure for the synthesis of 3-amino-6-bromopyrazine-2-carboxamide from 3-aminopyrazine-2-carboxamide: 12 g of 3-aminopyrazine-2-carboxamide was dissolved in 150 mL of acetic acid and 19 g of bromoform was added slowly and dropwise. The reaction mixture was heated to reflux temperature and stirred continuously for 3 hours. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure, followed by liquid-liquid extraction with the addition of water and ethyl acetate. The organic phases were combined and concentrated and the resulting residue was purified by silica gel column chromatography. The final isolation afforded 10 g of 3-amino-6-bromopyrazine-2-carboxamide.

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