Carbon–carbon double bond isomerization in heterocyclic hydrazine derivatives

Double bond isomerization by in situ generated ruthenium hydride catalyst in 6- to 9-membered hydrazine heterocycles including an endocyclic N–N bond was investigated. Based on the results of the experiments, a conclusion was made that the generation of resonance-stabilized enehydrazides is generally favored, but in some cases, the reaction pathway is presumably also highly dependent of steric interactions. With the current method, two novel enehydrazide heterocycles and one enehydrazine heterocycle were produced and characterized.