Synthesis of 1-acyl-5-pyrazolones and pyrrolidino[2,3-c]pyrazol-3-ones

The reactivity of acetamidrazones I in strong basicity conditions was examined. When compounds I are reacted with equivalent quantities of α-haloketones in sodium alcoholate, the pyrrolidino[2,3-c]pyrazol-3-ones IV were obtained by intermediate formation of 1-acyl-3-amino-5-pyrazolones III .