Acid-Catalyzed Reactions of N-Arylhydroxylamines and Related Compounds with Benzene. Iminium-Benzenium Ions

Article abstract of DOI:10.1021/ja00393a025

N-Arylhydroxylamines react with benzene in the presence of trifluoroacetic acid (TFA) at room temperature to give diphenylamines.When TFA was replaced by a strong acid, trifluoromethanesulfonic acid (TFSA), the major products were aminobiphenyls.The nature of the reaction was explored by reactions of 4-substituted phenylhydroxylamines and dialkylaniline N-oxides with benzene.Thus, it was demonstrated that the reactive intermediates are onium-benzenium dications which are trapped by benzene to give aminobiphenyls by a mechanism similar to the Friedel-Krafts alkylation.Further evidence for the proposed reaction mechanism was the observation that nitrosobenzene and azoxybenzene reacted with benzene to give analogous products in the presence of the stronger acid.