Investigation of the phenylation of methyl-quinolines using tritium-labeled nucleogenic phenyl cations

Abstract

The phenylation of methylquinolines by nucleogenic phenyl cations was studied. This reaction led to a product mixture through electrophilic addition and electrophilic substitution, with composition depending on the methyl substituent position. In the case of 4-methylquinoline, the electron-donating methyl group in the para position markedly increased the yield of N-phenylquinolinium derivative, while the low yield of the quinolinium salt in the case of 8-methylquinoline was due to the two factors - low basicity of the nitrogen atom in comparison to 4-methylquinoline and steric hindrance by the methyl group, which led to predominant electrophilic substitution.