反应详情

As described for example 112a, (5-methyl-pyrazol-1-yl)-acetic acid ethyl ester in ethanol was reacted with hydrazine hydrate (2 equivalents) and the resulting mixture was heated under reflux for 8 h. The mixture was cooled to rt and the precipitated product was filtered off, dried and crystallized from toluene. The title compound (95% purity, based on NMR) was obtained as a white solid (yield: 45%). 1H-NMR (300 MHz, DMSO): δ=2.24 (s, 3H), 4.29 (s, 2H), 4.65 (s, 2H), 6.00 (d, J=1 Hz, 1H), 7.55 (d, J=1 Hz, 1H), 9.27 (s, 1H).

1. temperaturethe resulting mixture was heated
2. temperatureunder reflux for 8 h
3. filtrationthe precipitated product was filtered off
4. customdried
5. customcrystallized from toluene