Reactions of 4‐(Dicyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one Towards Amines and Phenols

3‐Methyl‐1‐phenyl‐2‐pyrazoline‐4,5‐dione ( 3 ) condenses readily with malononitrile in refluxing ethanol to yield 4‐(dicyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one ( 4 ). Compound 4 readily reacts with aliphatic, aromatic, and heterocyclic amines to yield 4‐substituted (aminocyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐ones ( 8 ). o ‐Substituted arylamines afford also 4‐substituted (arylcyanomethylene)pyrazolones, which readily cyclize to give the 4‐azolylidene pyrazolones 9a–c . Secondary and tertiary amines and activated phenols condense with 4 by hydrogen cyanide elimination to yield compounds 10a–c and 10a, b , respectively.