Step 3: To a solution of 5-fluoro-2-((trimethylsilyl)alkynyl)pyridin-3-amine (2.22 g, 10.7 mmol) in N,N-dimethylformamide (DMF, 30 mL) was added sodium hydride (60% Mineral Oil Dispersion, 1.025 g, 42.7 mmol) in one batch at 0 °C and under nitrogen protection. After addition, the reaction mixture was stirred at room temperature for 2 hours. Subsequently, the reaction solution was slowly poured into ice water and extracted with ethyl acetate (EtOAc). The organic phases were combined, dried over anhydrous magnesium sulfate (MgSO), filtered and concentrated under reduced pressure to give 1.46 g of 6-fluoro-1H-pyrrolo[3,2-b]pyridine as a brown solid (100% yield). Mass spectrum (ESI): m/z = 137.2 [M + H]