Electrochemical behavior of the product of coupling of crotononitrile with aryldiazonium salts

It has been reported that compounds la-c couple with aromatic diazonium salts to yield the corresponding hydrazones 2a-c, which readily cyclize into the pyridazines 3a-c, c.f. Plate 1. However, Mittelbach [1] reported that at least the product of coupling component 1 c with aromatic diazonium salts would be 3 c, so that compound 2 c could have never been isolated. This led Mettelbach [1] to suggest that the coupling products assigned by Elnagdi et al. [2] as being of the types of compound 2 would be in fact related to compounds 3