反应详情

温度

85 °C

To a solution of ethyl 3-oxo-3-(pyridin-2-yl)propanoate (25.00 g, 129 mmol, Matrix Scientific) in EtOH (60 mL) was added methylhydrazine (6.81 mL, 129 mmol). The mixture was heated at about 85° C. for about 3 h then cooled to rt and concentrated at rt under reduced pressure. The material was triturated with Et2O (40 mL). The solids were collected by filtration then washed with Et2O to give 1-methyl-3-(pyridin-2-yl)-1H-pyrazol-5-ol (17.80 g, 79%). The filtrate was concentrated under reduced pressure then the material was triturated with 1:1 DCM/Et2O. The solids were collected by filtration and washed with Et2O to give a second crop of 1-methyl-3-(pyridin-2-yl)-1H-pyrazol-5-ol (1.20 g, 5%): LC-MS (Table 1, Method g) Rt=1.05 min, m/z 176 (M+H)+; 1H-NMR (DMSO, Bruker 400 MHz) δ 11.05 (s, 1H), 8.50-8.47 (m, 1H), 7.83-7.80 (m, 1H), 7.78-7.69 (m, 1H), 7.24-7.19 (m, 1H), 5.90 (s, 1H), 3.57 (s, 3H).

1. temperaturethen cooled to rt
2. concentrationconcentrated at rt under reduced pressure
3. customThe material was triturated with Et2O (40 mL)
4. filtrationThe solids were collected by filtration
5. washthen washed with Et2O