General procedure for the synthesis of methyl 5-hydroxypyrazine-2-carboxylate from methanol and 5-oxo-4,5-dihydropyrazine-2-carboxylic acid: Acetyl chloride (152 mL, 2.08 mol) was slowly added dropwise to methanol (5 L) at -20 °C. After the dropwise addition was completed, stirring was continued at this temperature for 30 minutes. Subsequently, 5-hydroxypyrazine-2-carboxylic acid (100 g, 714 mmol) was added and the mixture was heated to reflux and the reaction was maintained for 2 hours. Upon completion of the reaction, the solvent was removed by vacuum concentration and the residue was recrystallized from methanol (400 mL) to give 71 g (464 mmol) of methyl 5-hydroxypyrazine-2-carboxylate in 65% yield.
