Tandem Carbon−Carbon and Carbon−Chlorine Bond Formation by Cu(II) Chloride-Promoted [3,3] Sigmatropic Rearrangement of N-Allylhydrazones

A new copper(II) chloride-promoted rearrangement of N -allylhydrazones has been developed. Treatment of a number of aromatic N -allylhydrazones with copper(II) chloride provides the formation of both a new carbon−carbon bond and a carbon−chlorine bond in the same reaction. Substrate studies revealed that the carbon−carbon bond-forming step proceeds by way of a concerted [3,3] sigmatropic rearrangement and selectively generates trans-substituted alkenes.