2,4-Dichloro-7H-pyrrolo[2,3-d]pyrimidine (200 mg, 1.06 mmol) was used as starting material and dissolved in acetonitrile (5.0 mL). Subsequently, 1-chloromethyl-4-fluoro-1,4-diazabicyclo[2.2.2]octanebis(tetrafluoroborate) (561.6 mg, 1.6 mmol) and acetic acid (1 mL) were added sequentially to this solution. The reaction mixture was heated at 80 °C and stirred continuously for 24 hours. Upon completion of the reaction, the organic layer was separated, dried with anhydrous magnesium sulfate, filtered to remove the desiccant, and the filtrate was subsequently concentrated under reduced pressure. The residue was purified by column chromatography to afford the target compound 2,4-dichloro-5-fluoro-7H-pyrrolo[2,3-d]pyrimidine (170.0 mg, 80.1% yield). The product was confirmed by NMR hydrogen spectroscopy (500 MHz, CD3OD) with a chemical shift δ of 7.36 (s, 1H).