Synthesis
The general procedure for the synthesis of 2,4-dihydroxy-6-methyl-5-nitropyrimidine from 6-methyluracil was as follows: the procedure was adapted from the Journal of Medicinal Chemistry. 6-Methylpyrimidine-2,4(1H,3H)-dione (7.0 g, 55.56 mmol) was slowly added to ice-cooled but concentrated sulfuric acid (26 mL), and the rate of addition was controlled to keep the internal temperature of the reaction system from exceeding 40 °C. Subsequently, fuming nitric acid (5.2 mL) was slowly added dropwise to the reaction mixture at a temperature below 15 °C. After completion of the dropwise addition, the cooling bath was removed and the reaction mixture was stirred at room temperature for 30 min. The reaction solution was carefully poured into 100 mL of crushed ice and stirred for 10 minutes before collecting the solid product that precipitated. The solid was washed with cold water and then dried under vacuum in the presence of phosphorus pentoxide. A yellow-green solid of 6-methyl-5-nitropyrimidine-2,4(1H,3H)-dione (7.92 g, 83% yield) was finally obtained.
References
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[2] Patent: WO2009/62258, 2009, A1. Location in patent: Page/Page column 97-98
[3] Synthetic Communications, 2007, vol. 37, # 14, p. 2421 - 2431
[4] ChemMedChem, 2018, vol. 13, # 2, p. 178 - 185
[5] Patent: CN105906621, 2016, A. Location in patent: Paragraph 0030
