370103-25-6

370103-23-4

370103-25-6

General procedure for the synthesis of 2,5-dimethoxy-4-chloropyrimidine from 2,5-dimethoxy-4-hydroxypyrimidine: Example 4: 15.6 g (0.1 mol) of 2,5-dimethoxy-4-hydroxypyrimidine was suspended in 25 g of toluene. To the suspension was added 46.0 g of phosphoryl chloride and the mixture was heated to 80°C. 20.2 g of triethylamine was added slowly and dropwise over a period of 1 hour, followed by continued stirring at 80 °C for 30 minutes. Upon completion of the reaction, the mixture was poured into 600 g of ice water, stirred for 12 h, and the pH was adjusted with sodium hydroxide solution to 5. The toluene phase was separated, and the aqueous phase was extracted with toluene (50 mL each time) three times. The toluene extracts were combined and concentrated to dryness to give 12.57 g of 4-chloro-2,5-dimethoxypyrimidine as light yellow crystals with a characteristic odor. The melting point of the product was 78-80°C. Nuclear magnetic resonance hydrogen spectrum (1H-NMR) data: 3.860 ppm (s, 3H), 3.909 ppm (s, 3H), 8.446 ppm (s, 1H). Nuclear magnetic resonance carbon spectroscopy (13C-NMR) data: 55.11 ppm (OCH3), 57.42 ppm (OCH3), 143.90 ppm (C6), 145.09 ppm (C5), 149.67 ppm (C4), 158.28 ppm (C2). Gas chromatography-mass spectrometry (GC/MS) analysis showed product purity >98% with molecular ion peaks (M+) of 174/176 g/mol. yield was 72%.