General procedure for the synthesis of 1,3-dimethyl-6-aminouracil from 4-amino-2,6-dihydroxypyrimidine and iodomethane: 4-amino-2,6-dihydroxypyrimidine (1.27 g, 10 mmol) was added to a pre-heated ethanol solution (50 ml) containing KOH (0.56 g, 10 mmol) and heated continuously for 40 min. After completion of the reaction, the mixture was cooled to room temperature followed by addition of iodomethane (20 mmol). The reaction mixture was stirred under heating conditions for 8 hours, after which it was cooled to room temperature. The reaction mixture was poured into cold distilled water (100 ml) to induce precipitation of the final product 1,3-dimethyl-6-aminouracil. The precipitate was collected by filtration and washed with distilled water (100 ml). Finally, recrystallization from methanol gave 1,3-dimethyl-6-aminouracil in yellow crystalline form.
