Step 2: Synthesis of 4-methyl-2-pyrimidine carboxylic acid; 4-methyl-2-pyrimidinecarbonitrile (500 mg, 4.20 mmol) was reacted with an aqueous solution (12.5 mL) of sodium hydroxide (504 mg, 12.6 mmol) for 1 h at 60°C with stirring. After completion of the reaction, the mixture was cooled to room temperature and the pH was adjusted to 2 with citric acid, followed by extraction with CHCl3:i-PrOH (3:1, 2 × 20 mL). The organic phases were combined, dried with anhydrous MgSO4 and concentrated under reduced pressure to afford the title compound 4-methyl-2-pyrimidinecarboxylic acid (0.294 g, 51% yield), and the product was used for subsequent reactions without further purification.1H NMR (300 MHz, D2O) δ 8.50 (d, J = 5.2 Hz, 1H), 7.31 (d, J = 5.3 Hz, 1H).
