General procedure for the synthesis of 6-amino-9-((2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-3,9-dihydro-2H-purine-2-thione from carbon disulfide and the compound (CAS: 57004-06-5): In a reaction flask, tetrahydrofuran (5 mL), the compound (II) (27 g. 100 mmol), methanol (100 mL), carbon disulfide (100 mL) and dimethyl sulfoxide (500 mL) and mixed with thorough stirring. The reaction mixture was heated to 140-150 °C and the reaction was continuously stirred at this temperature for 12 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was washed sequentially with ethanol and water, and then with saturated aqueous sodium chloride solution, and finally dried to give 24 g of the target product in 80% yield.
