General procedure for the synthesis of 2-aminopyrimidine-5-carboxylic acid from methyl 2-aminopyrimidine-5-carboxylate: methyl 2-aminopyrimidine-5-carboxylate (300 mg, 2.0 mmol) was dissolved in methanol (5 mL) containing a small amount of water. Lithium hydroxide (122 mg, 5.1 mmol) was added to the solution and the reaction mixture was subsequently stirred at 60 °C overnight. Upon completion of the reaction, the mixture was concentrated under reduced pressure, and the residue was diluted with water and the pH was adjusted to 4 with 1 M HCl solution.At this point, 2-aminopyrimidine-5-carboxylic acid precipitated as a white solid, and the product was collected by filtration under vacuum to give 244 mg in 90% yield. The product was characterized by 1H NMR (DMSO-d6): δ 12.73 (1H, broad peak), 8.63 (2H, single peak), 7.44 (2H, broad peak).
