ii) 5-Aminopyrazine-2-carbonitrile (0.208 mmol) was dissolved in acetonitrile (1 mL) and added slowly and dropwise to a stirred solution of copper (II) bromide (0.25 mmol) and tert-butyl nitrite (0.31 mmol) in acetonitrile (2 mL). The reaction mixture was stirred at a constant temperature at 60 °C for 1 hour. After completion of the reaction, the reaction solution was diluted with ethyl acetate (15 mL) and washed twice with 1N aqueous hydrochloric acid. The organic phase was dried over anhydrous sodium sulfate and purified by silica gel column chromatography (eluent: hexane/ethyl acetate) to afford the target compound 2-bromo-5-cyanopyrazine in 49% yield.1H NMR (CDCl3) δ (ppm): 8.83 (s, 1H); 8.71 (s, 1H).
