309947-86-2

24424-99-5

66224-66-6

309947-86-2

Adenine (1.35 g, 10 mmol) and 4-dimethylaminopyridine (DMAP, 122 mg, 1 mmol) were dissolved in tetrahydrofuran (THF, 50 mL) under argon protection. Subsequently, di-tert-butyl dicarbonate (Boc2O, 9.38 g, 43 mmol) was added to this solution. The reaction mixture was stirred at room temperature for 5 hours. After completion of the reaction, the solvent was removed under reduced pressure and ethyl acetate (EtOAc, 400 mL) was added to dissolve the residue. The resulting solution was washed sequentially with 1N hydrochloric acid (HCl, 30 mL) and saturated sodium chloride solution (NaCl, 3 x 100 mL). The organic phase was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The residue was dissolved in a solvent mixture of methanol (100 mL) and saturated sodium bicarbonate solution (NaHCO3, 45 mL), followed by stirring for 1.5 hours at 50 °C. After completion of the reaction, the solvent was removed under reduced pressure and diluted by adding water (100 mL). The aqueous phase was extracted with chloroform (CHCl3, 2 x 300 mL), the organic phases were combined and dried over anhydrous sodium sulfate (Na2SO4). After removal of the solvent under reduced pressure, the crude product was purified by fast column chromatography (eluent: cyclohexane/ethyl acetate, 10:90) to afford 6-[bis(Boc)amino]purine (2.44 g, 73%) as a white solid.1H NMR (DMSO-d6) δ: 13.69 (s, 1H, NH), 8.80 (s, 1H, H-2), 8.63 (s, 1H H-8), 1.36 (s, 18H, C(CH3)3) ppm.