Electrophilic ipso-substitutions. Part 2. Reactions of 3-substituted indoles and 4-substituted NN-dimethylanilines with arenediazonium ions

Abstract

3-Substituted indoles and 4-substituted NN-dimethylanilines react with arenediazonium ions to form 3-arylazoindoles and 4-arylazo-NN-dimethylanilines, respectively. The formation of the σ-complex intermediate was interpreted both as electrophilic ipso-attack and as coupling of two radicals deriving from an electron transfer process. Both mechanisms are discussed on the basis of the experimental evidence and on the substrate oxidation potentials. The leaving abilities of the substituents are discussed on the basis of the experimental results.