synthesis of 5-Fluoro-4,6-dihydroxypyrimidine: Formamidine acetate (2.06 g, 20 mmol) was added to the solution of sodium (1.38 g, 60 mmol) in anhydrous ethanol (40 mL) and the mixture was heated to reflux. Diethyl 2-fluoromalonate (3.20 g, 18 mmol) was added dropwise over 20 minutes and the mixture was heated at reflux for 6 h. After cooling to room temperature, the solution was evaporated to dryness, the residue was dissolved in water (20 mL), acidified with HCl (5 mL), the precipitate was filtered, washed with water (5 mL), ethanol (2 × 5 mL) and diethyl ether (2 × 5 mL). After drying in vacuo, 5-fluoro-4,6-dihydroxypyrimidine (1.50 g, 64%) was obtained as a brown powder.
m.p.: >300 °C; ([M + H]+ , 131.0244, C4H4FN2O2 requires: [M]+ , 131.0257); IR (neat, cm-1 ) 3053, 2639, 1633, 1547, 1388, 1213; δH (DMSO d6, 400 MHz) 7.90 (1H, s, C-H), 12.38 (2H, bs, OH); δF (DMSO d6, 376 MHz): -178.06 (s); δC (DMSO d6, 100 MHz) 132.79 (d, 1 JCF 235.6, C-F), 144.46 (d, 4 JCF 7.7, C-H), 155.83 (d, 2 JCF 15.0, C-OH); m/z (ASAP) 131 (100%, [M + H]+ ).21a
