Formation of N-cyclopropylhydrazones by azo coupling of cyclopropyldiazonium with aliphatic CH acids

Decomposition of N-cyclopropyl-N-nitrosourea under the action of K₂CO₃ or KOH containing 15—20% of H₂O at 0—7 °C gives rise to cyclopropyldiazonium, which reacts with some -diketones, methyl cyanoacetate, or malonodinitrile to form the corresponding cyclopropylhydrazones. The latter compounds are analogous to products of azo coupling and isomerization of aryldiazonium ions with the above-mentioned substrates. These transformations provide the first example of azo coupling of the cyclopropyldiazonium ion in the series of activated aliphatic CH acids.