Step 1: 2,4-Dihydroxypyridine (20.3 g, 183.0 mmol) was added to a mixed solution of 2-methoxyethanol (400 mL) and 55% hydrazine hydrate (80 mL). The reaction mixture was stirred at room temperature and refluxed for 24 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure. The resulting residue was recrystallized from ethanol to give 4-hydrazinylpyridin-2(1H)-one as a white solid (yield: 88.3%).TLC detection conditions: dichloromethane/methanol=10/1 (v/v); Rf=0.1.1.1H-NMR (CDCl3) δ: 10.30 (brs, 1H), 7.67 (s, 1H), 7.10 (d, 1H) , 5.79 (d, 1H), 5.54 (s, 1H), 3.91 (brs, 2H).
