Synthesis of methyl 2-chloropyrimidine-4-carboxylate: 2-chloropyrimidine-4-carboxylic acid (4.76 g, 30 mmol) was dissolved in dichloromethane (30 mL) and dimethylformamide (0.3 mL), to which was added Slowly add oxalyl chloride (5.72g, 45mmol) dropwise, stir at room temperature for 2 hours, Chemicalbook, after concentrating to an appropriate volume, add dropwise to anhydrous methanol (50mL) placed under ice bath conditions, after the dropwise addition, the reaction is transferred to The reaction was carried out at room temperature for 2 hours, and concentrated under reduced pressure to obtain (5.17 g, yield 100%).