The general procedure for the synthesis of methyl 6-chloro-3-methylpyrazine-2-carboxylate from the compound (CAS:1166831-47-5) is as follows:Preparation of intermediate 64-3 (methyl 6-chloro-3-methylpyrazine-2-carboxylate): intermediate 64-4 (314 mg, 1.87 mmol) was reacted with phosphorochloridic acid (2.088 mL, 22.40 mmol) in a The suspension formed was stirred and reacted at 90 °C for 70 min. Subsequently, the reaction mixture was slowly added dropwise to water (20 mL) over a period of 2-3 hours, during which the temperature was kept below 40 °C by external cooling. Upon completion of the reaction, extraction was carried out with dichloromethane (DCM, 5 x 50 mL), the organic layers were combined and dried with anhydrous magnesium sulfate (MgSO4). The dried organic phase was filtered and concentrated to give a yellow oil. The crude product was purified by fast silica gel column chromatography with an elution gradient of 0 to 20% ethyl acetate (EtOAc)/isohexane. The pure grades were collected and concentrated to dryness to give the final title compound methyl 6-chloro-3-methylpyrazine-2-carboxylate (142 mg, 40.8% yield) as a white solid. Its nuclear magnetic resonance hydrogen spectrum (1H NMR, 400 MHz, CDCl3) data were as follows: δ 2.76 (3H, s), 3.94 (3H, s), 8.56 (1H, s); Mass Spectrum (m/z): 187 (M + H)+.
