Reactions with 4‐Bromo‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one: New Fused Pyrazole Derivatives

Abstract New furo[2,3‐c]pyrazoles and pyrano[2,3‐c]pyrazoles were synthesized from 4‐bromo‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one and active methylenenitriles, ethyl acetoacetate or phenylhydrazine. The constitutions of the new heterocycles were established by elemental analyses and spectroscopic data.