Piperylone is a pyrazolone with analgesic, anti-inflammatory, and antipyretic properties.
Hydrazone formation of 1-methyl-4-piperidone (1) with benzohydrazide (2) gives (3). Catalytic hydrogenation using Adams' catalyst gives the substituted hydrazine (6) after acid-catalyzed hydrolysis to remove the benzoyl group and neutralization. The pyrazolone ring is formed in a condensation reaction with ethyl 2-benzoylbutanoate (7), yielding piperylone.