The general procedure for the synthesis of 4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidines from 5-bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidines and iodomethane was as follows: n-butyllithium (4.08 mL, 6.52 mmol) was slowly added dropwise under nitrogen protection to a solution of 5-bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidines (689 mg. 2.96 mmol) in a solution of tetrahydrofuran (40 mL), keeping the reaction temperature at -78 °C, and the dropwise addition time was controlled within 5 min. The resulting suspension was continued to be stirred at -78 °C for 30 min. Subsequently, methyl iodide (0.295 mL, 4.74 mmol) was added and the reaction mixture was allowed to slowly warm up to room temperature. After the reaction was completed, the reaction mixture was diluted with water (25 mL) and extracted with ethyl acetate (50 mL). The organic layer was washed with brine (25 mL), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by fast silica gel column chromatography with isohexane/ethyl acetate as eluent (20% to 50% gradient elution). The pure grades were collected and concentrated to dryness under reduced pressure to afford 4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine (244 mg, 49.1% yield) as a white solid. The structure of the product was confirmed by 1H NMR (400.13 MHz, DMSO-d6) and mass spectrometry: 1H NMR δ 2.42 (3H, d), 7.43 (1H, d), 8.51 (1H, s), 12.22 (1H, s); MS m/z [M+H]+ 168.
![5-Bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidine](/CAS/GIF/22276-95-5.gif)
![4-Chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine](/CAS/GIF/1618-36-6.gif)