A Convenient Access to Functionalized Pyrazole, Pyrazolyl‐Azole, and Pyrazolo[3,4‐d]Pyridazine Derivatives

Abstract 3‐(2‐Furyl)‐3‐oxopropanitrile reacts with keto and ester‐hydrazonyl chlorides to afford the corresponding acetyl‐ and ester‐pyrazole derivatives. The latter pyrazoles reacted with hydrazine and gave either the pyrazolo[3,4‐d]pyridazines or pyrazolylhydrazides. Treatment of the latter hydrazides with phenylisothiocyanate and with phenylisocyanate resulted in the formation of the pyrazolylthiadiazole and pyrazolyloxadiazole derivatives, respectively.