[Synthesis]
Ethyl 4-chloro-5H-pyrrolo[3,2-d]pyrimidine-7-carboxylate (500 mg, 2.22 mmol) was dissolved in N,N-dimethylformamide (4 mL, 50 mmol) and the solution was cooled to 0 °C. Sodium hydride (60% dispersed in mineral oil, 115.2 mg) was added to the solution at 0 °C and the reaction mixture was stirred for 20 min. Subsequently, iodomethane (165.5 μL, 2.659 mmol) was added and the reaction mixture was slowly warmed to room temperature. Upon completion of the reaction, the reaction was quenched with aqueous ammonium chloride and extracted three times with dichloromethane. The organic phases were combined, washed with saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by fast column chromatography (elution gradient: 0-100% heptane solution of ethyl acetate containing 15% methanol) to afford ethyl 4-chloro-5-methyl-5H-pyrrolo[3,2-d]pyrimidine-7-carboxylate as a solid (380 mg in 72% yield).1H NMR (500 MHz, DMSO-d6) δ 8.77 (s, 1H) 8.65 (s, 1H), 4.30 (q, J = 7.1 Hz, 2H), 4.16 (s, 3H), 1.32 (t, J = 7.1 Hz, 3H). |