Synthesis
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).
References
[1] Bioorganic and Medicinal Chemistry, 2014, vol. 22, # 9, p. 2739 - 2752
[2] Patent: WO2008/121861, 2008, A2. Location in patent: Page/Page column 67-68
[3] RSC Advances, 2014, vol. 4, # 105, p. 61193 - 61199
[4] Research on Chemical Intermediates, 2016, vol. 42, # 4, p. 3169 - 3181
[5] Journal of the Iranian Chemical Society, 2013, vol. 10, # 2, p. 213 - 219
