To a solution of 3,5-dibromopyrazin-2-amine (2.00 g, 7.91 mmol) in anhydrous THF (24 mL) was sequentially added triethylamine (3.3 mL, 24 mmol), cuprous iodide (151 mg, 0.79 mmol), and Pd(PPh3)2Cl2 (catalytic amount). The reaction mixture was cooled to -5 °C under nitrogen protection, and then trimethylsilylacetylene (1.07 mL, 7.50 mmol) was slowly added dropwise. After the dropwise addition, the reaction system was slowly warmed to 0 °C and stirred at this temperature for 1.5 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure to remove the solvent, and the resulting residue was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate, 5:1, v/v) to afford the target product, 3-[(trimethylsilyl)alkynyl]-5-bromopyrazin-2-amine, as a black oily substance (42 mg, 94% yield). Mass spectrum (ESI, positive ion mode) m/z: 272.00 [M + H]+; 1H NMR (400 MHz, CDCl3) δ (ppm): 8.04 (s, 1H), 5.14 (s, 2H), 0.30 (s, 9H).
