Convergent synthesis of 2,3-bisarylpyrazolones through cyclization of bisacylated pyrazolidines and hydrazines

Cyclization of various bisacylated hydrazines and pyrazolidines using DBU or sodium hydride leads to the formation of various mono-, bi- and tricyclic pyrazolone scaffolds in 41-98% yield. The convergent nature by which the precyclization intermediates are constructed allows for rapid derivatization about the pyrazolone core.