7418-65-7

16135-36-7

7418-65-7

The general procedure for the synthesis of 4-aminopyridine-3-carboxylic acid from 4-aminonicotinic acid methyl ester was as follows: to an aqueous ethanol solution of 4-aminopyridine-3-carboxylic acid methyl ester (2 g, 13.15 mmol) in stirring (120 mL, V/V=1:1) was added LiOH-H2O (1.21 g, 28.80 mmol) at room temperature, and the reaction mixture was subsequently heated to 80°C for 2 h (the progress of the reaction was monitored by TLC to confirm complete consumption of the feedstock). After completion of the reaction, the volatiles were removed under reduced pressure to give the crude product. The crude product was dissolved in water (30 mL) and washed with ethyl acetate (2 x 25 mL) to remove non-polar impurities. The aqueous layer was acidified to pH=1 with 1N HCl solution and subsequently extracted with ethyl acetate (2 x 10 mL). The organic extracts were combined and concentrated under reduced pressure to give a crude residue. The crude product was purified by crystallization from methanol (20 mL) to give finally 4-aminopyridine-3-carboxylic acid (1 g, 55% yield) as an off-white solid.LCMS (ESI+): m/z: 139.31 [M+H]+.