反应详情

Ethyl 1H-pyrazol-5-ylcarbamothioylcarbamate (4.64 g, 21.68 mmol) from 1a was added to 2N NaOH solution (51 mL). The reaction mixture was stirred at room temperature for 2½ hours and then acidified with 2NH2SO4. The resulting precipitate was collected by vacuum filtration, washed with water followed by diethyl ether, and then air dried to give 3.32 g (82%) of 2-thioxo-2,3-dihydropyrazolo[1,5-a][1,3,5]triazin-4(1H)-one as a pale yellow solid.

1. filtrationThe resulting precipitate was collected by vacuum filtration
2. washwashed with water
3. customair dried