Stage B - Synthesis of 4-chloro-5-ethoxycarbonyl-2-methoxypyrimidine: 99 g (0.5 mol) of 5-ethoxycarbonyl-4-hydroxy-2-methoxypyrimidine was suspended in 200 cm3 dimethylformamide (D.M.F.). Under stirring, 89 g (0.75 mol) of thionyl chloride was added slowly over about 5 minutes. The mixture was heated until the solid was completely dissolved. The resulting homogeneous solution was continued to be stirred at room temperature for 30 minutes. Under stirring, the reaction mixture was slowly poured into a mixture consisting of 250 g of ice and 1 L of water. After continued stirring for 15 min, the reaction product was extracted with benzene (2 x 400 cm3). The organic phases were combined and washed sequentially with dilute sodium bicarbonate solution and water, followed by drying with anhydrous magnesium sulfate. The organic phase was concentrated under reduced pressure to give 101.6 g of 4-chloro-5-ethoxycarbonyl-2-methoxypyrimidine in oil form in 94% yield. The product was purified by vacuum distillation with a boiling point of 120 °C (0.9 mmHg), and the distillate was crystallized after cooling with a melting point of 26-28 °C. Elemental analysis (C8H9ClN2O3, molecular weight 216.5): calculated values: C, 44.34; H, 4.16; N, 12.93. measured values: C, 44.18; H, 4.33; N, 12.88.
