The general procedure for the synthesis of 4-hydroxy-5-methoxypyrimidine from 5-methoxy-2-thio-2,3-dihydropyrimidin-4(1H)-one is as follows: 3.9 g of Ruannei nickel (slurry) was added to a 60 mL hydrothermal solution containing 4.1 g (0.026 mol) of 2-mercapto-5-methoxy-3H-pyrimidin-4-one (Example P1). The reaction mixture was stirred vigorously at reflux temperature for 8 hours and then filtered. The filtrate was combined with the wash grades and concentrated by evaporation on a hot water bath. The resulting residue was purified by ethanol recrystallization in the presence of activated carbon. Eventually 1.9 g of 4-hydroxy-5-methoxypyrimidine in needle form was obtained in 69% yield of the theoretical value, with a melting point of 206-208 °C.1H NMR (300 MHz, DMSO-d6) data were as follows: δ 7.828 ppm (s, 1H); 7.527 ppm (s, 1H); 3.728 ppm (s, 3H).
