Example 1A Synthesis of 5-bromo-2-pyrazinamine: 2-Aminopyrazine (15.0 g, 157 mmol) was dissolved in dichloromethane (900 mL), N-bromosuccinimide (28.2 g, 159 mmol) was added, and the reaction was stirred for 3.5 hours at room temperature. After completion of the reaction, the reaction mixture was filtered through diatomaceous earth (Celite). The filtrate was treated with silica gel (300 g) and subsequently concentrated under reduced pressure. The resulting crude product was purified by fast column chromatography with 30% ethyl acetate/hexane as eluent to give 22.09 g (81.5% yield) of the target compound 5-bromo-2-pyrazinamine. Mass spectrum (APCI(+)) m/z: 174 ([M + H]+); 1H NMR (300 MHz, CDCl3) δ: 8.09 (d, J = 1.4 Hz, 1H), 7.77 (d, J = 1.7 Hz, 1H), 4.30-4.78 (br s, 2H).
