反应详情

To a stirring solution of 2.0 g (13.87 mmol) of methyl acetopyruvate in 40 mL of absolute ethanol at 0° C. is added 0.48 mL (15.27 mmol, 1.1 equiv) of hydrazine. The resultion solution is stirred for 1 h at RT then heated to reflux for 3 h. The solution is then cooled to RT and the solvent removed in vacuo to give 5-methyl-2H-pyrazole-3-carboxylic acid methyl ester as a clear yellow oil which is used without further purification: 1H NMR (CDCl3, 300 MHz) δ6.61 (s, 1H), 3.97 (s, 3H),2.40 (s, 3H).

1. temperaturethen heated
2. temperatureto reflux for 3 h
3. temperatureThe solution is then cooled to RT
4. customthe solvent removed in vacuo