Potassium tert-butoxide (3.70 g, 33.0 mmol) was dissolved in THF (80 mL) under N2 protection. A solution of 5-bromo-3 - ((trimethylsilyl) ethynyl) pyrazine-2-amino (9.00 g, 33.0 mmol) in THF (84 mL) was slowly added dropwise over 30 min. After the dropwise addition, the mixture was stirred at room temperature for 30 min, Reflux reaction 1h, Cooled to room temperature and filtered. The filter cake was washed with ethyl acetate (200 mL) and saturated brine (50 mL x 2), and the aqueous phase was combined. And extracted with ethyl acetate (60 mL x 2). The organic phases were combined. The residue was subjected to column chromatography (eluent: PE / EtOAc (v / v) = 3/1) to give 5-Bromo-4,7-diazaindole 5.0 g of a yellow solid.
