Free-radical cyclisations of 2-aminoalka-2,5-dienenitriles

Abstract

The intramolecular free-radical cyclisations of a series of 2-(N-methylanilino)alka-2,5-dienenitriles 5–16 have been studied. These compounds have two alkenyl groups orientated in equal proximity to the radical centres. One alkenyl group contains both the cyano and the N-methylanilino substituents, while the other contains either an electron-withdrawing or an electron-donating group. Intramolecular free-radical cyclisations occur exclusively or predominantly on the amino-cyano substituted alkenyl group (C-3 attack). The radical cyclisation of 4-(2-bromobenzyl)methyl-3,5-dimethyl-2-(N-methylanilino)hepta-2,5-diene-1,7-dinitrile also occur exclusively at C-3.