Synthesis
To a solution of 6-chloro-9H-purine (3.00 g, 20.0 mmol) in anhydrous THF (100 mL) cooled to 0°C was added 60% sodium hydride (1.2 g, 30.0 mmol) in portions. The reaction mixture was stirred in an ice bath for 0.5 h. Then iodomethane (2.82 g, 20.0 mmol) was slowly added and stirring was continued for 1 h at room temperature. After completion of the reaction, the mixture was diluted with 100 mL of water and extracted with ethyl acetate (30 mL x 3). The organic layers were combined, dried with anhydrous magnesium chloride and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography with the eluent being a 20% ethyl acetate/petroleum ether solvent mixture. The white solid product 9-methyl-6-chloropurine was obtained in 74.6% (2.50 g) yield. The product was analyzed by ESI-MS, m/z: 169.1 [M + H]+; 1H NMR (300 MHz, DMSO-d6) δ: 3.72 (3H, s, CH3), 8.72 (1H, s, H-purine), 9.15 (1H, s, H-purine).
References
[1] European Journal of Medicinal Chemistry, 2014, vol. 89, p. 581 - 596
[2] Synthesis, 2007, # 2, p. 219 - 224
[3] Angewandte Chemie - International Edition, 2018, vol. 57, # 18, p. 5134 - 5138
[4] Angew. Chem., 2018, vol. 130, # 18, p. 5228 - 5232,5
[5] Bioorganic and Medicinal Chemistry, 2004, vol. 12, # 1, p. 139 - 149
