Copper catalyzed reaction of hydrazones with polyhalogenated compounds. An efficient approach to alkenes and diazadienes

Abstract

Catalytic olefination reaction represents new approach to the preparation of double C=C bond. N-unsubstituted hydrazones can be converted into alkenes by treatment with polyhalogenated alkanes in presence of a base and catalytic amounts of copper salts. The reaction has a wide synthetic scope allowing to prepare both alkyl and aryl substituted alkenes, including fluorinated and functionalized ones. We demonstrated also similar transformation with N-substituted hydrazones, as a result the new carbon-carbon bond forming reaction of N-monosubstituted hydrazones with polyhaloalkanes to produce 1,2-diazabuta-1,3-dienes has been developed. This highly efficient copper-catalyzed transformation features a broad scope with regard to all reaction components, as well as the possibility to perform the process in a much more convenient one-pot fashion starting with easily available aldehydes and hydrazines. The synthetic usefulness of the obtained halogenated azadienes was demonstrated in their reactions with O-, N-, S- and C-nucleophiles, which opened access to a variety of valuable acyclic and heterocyclic products. Mechanistic studies revealed that this Cu-catalyzed transformation proceeds via radical pathway.