Procedure for the synthesis of 2,6-dichloro-9-methyl-9H-purine (15b): potassium carbonate (K2CO3, 0.270 g, 1.95 mmol) was added to an anhydrous DMF (1.0 mL) solution of 2,6-dichloro-9H-purine (0.120 g, 0.635 mmol) at 0°C followed by the addition of iodomethane (0.20 mL, 3.21 mmol). The reaction mixture was stirred continuously at 0 °C for 5 hours. Upon completion of the reaction, the reaction was quenched with water and extracted with ethyl acetate (EtOAc). The organic layers were combined, washed with saturated brine, dried over anhydrous magnesium sulfate (MgSO4), concentrated and purified by silica gel (SiO2) column chromatography with an elution gradient from 100% hexane to 100% ethyl acetate (EtOAc) to afford the target product 15b (83.0 mg, 0.409 mmol, 64% yield) as a colorless solid. The product characterization data were as follows: IR (ATR, neat) 3067, 1554, 1360, 1333, 1223, 1147 cm-1; 1H NMR (CDCl3, 600 MHz) δ 8.09 (s, 1H), 3.89 (s, 3H); 13C NMR (CDCl3, 150 MHz) δ 153.3, 152.7, 151.3, 146.4, 130.4, 30.4.
