Example 127: Preparation of 5-methyl-3-trifluoromethyl-1H-pyrazole
Hydrazine hydrate (945 μl, 30 mmol) was slowly added to a solution of 1,1,1-trifluoro-2,4-pentanedione (4.62 g, 30 mmol) in methanol (20 ml) at 0 °C. The reaction mixture was gradually warmed up to room temperature and stirred at that temperature for 16 hours. After completion of the reaction, the solvent was removed by concentration under reduced pressure to give 5-methyl-3-trifluoromethyl-1H-pyrazole as a yellow solid (4.5 g, 95% yield).
1H-NMR (400 MHz, CDCl3): δ 2.35 (s, 3H, CH3), 6.32 (s, 1H, CH), 9.88 (bs, 1H, NH) ppm.
