1,3-Migration of a cyano-group in substituted 3-cyanopropyl radicals

Abstract

The free radical addition of carbon tetrachloride to 2,2-dichlorobut-3-enonitriles gives both normal and rearranged addition products, namely hexachlorohexanonitriles and 3-cyanohexachloropentanes, respectively. The latter products are believed to be formed by migration of the cyano-group in the intermediate 3-cyanopropyl radical formed on addition of a trichloromethyl radical to the substrate. The migration is greatly assisted by methyl substituents in the 2-position, commensurate with migration through a four-membered cyclic intermediate radical. Some evidence is also presented for the formation of transient trichloroethylcyclopropanes when the initiating catalyst is benzoyl peroxide.