General procedure for the synthesis of ethyl 5-methylpyridine-2-carboxylate from 2-cyano-5-methylpyridine and ethanol: To a solution of 2-cyano-5-methylpyridine (5 g, 42.3 mmol, 1.00 equiv) in ethanol (40 mL) was added concentrated sulfuric acid (10 mL, 4.00 equiv). The resulting solution was stirred at 80 °C for 48 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature (25 °C). Subsequently, the mixture was concentrated under reduced pressure to remove the solvent. The concentrated residue was diluted with water (100 mL) and the pH was adjusted with potassium carbonate to 8-9. The aqueous phase was extracted with ethyl acetate (3 x 100 mL) and the organic phases were combined. The organic phase was washed sequentially with water (3 × 50 mL) and saturated saline (3 × 50 mL). Finally, the organic phase was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford ethyl 5-methylpyridine-2-carboxylate (3 g, 43% yield) as a light yellow oil.LC-MS analysis showed the molecular ion peak of the target product m/z = 166 [M + H]+ .
