24241-18-7

89123-58-0

The general procedure for the synthesis of 5-bromo-2,3-diaminopyrazine from 2-amino-3,5-dibromopyrazine was as follows: step 1: 2-amino-3,5-dibromopyrazine (3 g, 11.64 mmol) was suspended in a 25% aqueous ammonia solution (15 mL) in a sealed tube and the reaction was heated for 16 h at 110 °C. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was partitioned between ethyl acetate and water (3 x 50 mL). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography with 15% ethyl acetate-hexane mixed solvent as eluent to afford 5-bromo-2,3-diaminopyrazine as a yellow solid (2.1 g, 93% yield). Mass spectrum (electrospray ionization) m/z: 189 ([M+H]+).