1428929-49-0

253315-22-9

Compound 1 (CAS: 1428929-49-0, 8.66 g, 40.43 mmol, 1.0 eq.) was dissolved in anhydrous ethanol (80 mL), followed by slow addition of 3 M aqueous sodium hydroxide solution (40.40 mL, 121.3 mmol, 3.0 eq.). The reaction mixture was stirred overnight at room temperature. Upon completion of the reaction, the solvent was removed by reduced pressure distillation and the residue was dissolved in deionized water (60 mL). The aqueous phase was extracted twice with ether (40 mL × 2) to remove organic impurities. Subsequently, the pH of the aqueous phase was adjusted to 3 with 2 M aqueous hydrochloric acid, at which time a white solid precipitated. The white solid was collected by filtration and dried to give 6-(1H-pyrazol-1-yl)nicotinic acid (7.42 g, 97% yield). The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ 6.65 (dd, J = 2.7, 1.6 Hz, 1H, Ar-H), 7.92 (dd, J = 1.6, 0.8 Hz, 1H, Ar-H), 8.04 (dd, J = 8.6, 0.8 Hz, 1H, Ar-H), 8.44 (dd, J = 8.6 , 2.3 Hz, 1H, Ar-H), 8.70 (dd, J = 2.7, 0.8 Hz, 1H, Ar-H), 8.96 (dd, J = 2.3, 0.8 Hz, 1H, Ar-H), 13.44 (s, 1H, COOH).