A mixture of 5-phenoxypicolinic acid (83 mg, 0.39 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (191 mg, 1 mmol), N-hydroxybenzotriazole (135 mg, 1 mmol), triethylamine (0.2 mL) and dichloromethane (5 mL) was stirred at 25° C. for 0.5 hour. And then 3-(aminomethyl)-4,6-dimethylpyridin-2-ol (76 mg, 0.5 mmol) was added to the mixture. The resultant mixture was stirred at 25° C. for 12 hours. Then water (20 ml) was added to the mixture and the mixture was extracted with dichloromethane (30 mL×3). The combined organic phase was dried by sodium sulfate and then filtered. The filtrate was concentrated in vacuo. The residue was purified by column chromatography (silica gel, dichloromethane/methanol=20:1) to give N-((2-hydroxy-4,6-dimethylpyridin-3-yl)methyl)-5-phenoxypicolinamide (Compound I-21) as a white solid (50 mg, 37%). LRMS (M+H+) m/z: calcd 349.15. found 349. HPLC purity (214 nm): 99%. 1H NMR (300 MHz, d6-DMSO): δ 11.53 (s, 1H), 8.56 (t, J=6.0 Hz, 1H), 8.37-8.36 (m, 1H), 8.01 (d, J=8.7 Hz, 1H), 7.48-7.42 (m, 3H), 7.26-7.16 (m, 3H), 5.86 (s, 1H), 4.32 (d, J=6.0 Hz, 2H), 2.22 (s, 3H), 2.10 (s, 3H).
