145091-87-8

141-97-9

132712-71-1

The general procedure for the synthesis of 3-methyl-1H-pyrazol-5-ol from ethyl acetoacetate was as follows: to a methanol (5 mL) suspension of hydrazine hydrate (2.6 g, 20 mmol) was slowly added ethyl acetoacetate (1.0 g, 20 mmol). The reaction mixture was heated to reflux for 2 hours. Upon completion of the reaction, the solvent was removed by vacuum evaporation to afford the white solid product 3-methyl-1H-pyrazol-5-ol (1.92 g, 98% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 2.08 (s, 3H), 5.20 (s, 1H), 10.07 (br s, 1H).