Anodic cyanation of tert-butylated anisoles: competitive aromatic additions and substitutions

Abstract

The electrooxidation of several tert-butylated anisoles has been carried out in methanol containing sodium cyanide at a Pt anode in a divided cell. Two types of reactions occurred competitively, aromatic-ring addition and substitution. Increasing the level of tert-butyl substitution raises the relative extent of addition to the aromatic ring. An MO calculation has indicated that the order of orientational preference for substitution of the aromatic hydrogen of alkylanisole cation radicals is explained in terms of the LUMO electron densities calculated for the cation radicals. The effect of structure on the oxidation potential of alkylanisoles has also been studied. para Substitution lowers the oxidation potential while ortho substitution raises the potential.