Step 2: Synthesis of 5-bromo-3-ethynylpyrazin-2-amine
A solution of 5-bromo-3-[(trimethylsilyl)alkynyl]pyrazin-2-amine (2.5 g, 9.25 mmol) and potassium carbonate (1.279 g, 9.25 mmol) in methanol (40 mL) was added to a 150 mL round-bottomed flask, and the reaction mixture was brown in color. The reaction was stirred at room temperature for 30 minutes. After completion of the reaction, the mixture was extracted with dichloromethane and the organic layer was washed sequentially with water and brine. The organic layer was separated, dried with anhydrous magnesium sulfate, filtered and the solvent was concentrated under reduced pressure to give a brown solid product (1.54 g).
Product Characterization:
LCMS: retention time 0.78 min, mass-to-charge ratio m/z 200.2 [M + H]+; analytical method: 2 min low pH method.
1H NMR (400 MHz, DMSO-d6) δ 8.12 (1H, s), 6.86 (2H, br s), 4.81 (1H, s).
