Amine oxidation and the chemistry of quinone imines. Part I. 3-Methoxy-4-t-butylaniline

Abstract

With potassium ferricyanide or silver oxide the oxidation of 3-methoxy-4-t-butylaniline gives an azobenzene (4) and three phenazines (5)–(7). Chromatographic separation of the ferricyanide oxidation products on neutral alumina results in the formation of N-aryl-p-quinone imines (8) and (9), the NN′-diaryl-p-quinone di-imine (10), and an N-arylphenazineimine (11). With the exception of compounds (8) and (10) these products are also formed during chromatography of the silver oxide oxidation products, in which the presence of the N-aryl-o-quinone di-imine (27) is disclosed. The latter is shown to be the precursor of the quinone imines (9) and (11).

Chemical and spectroscopic evidence is advanced for the structures of these products, and their likely origin is demonstrated. The intermediacy and subsequent rearrangement of an iminocyclohexadiene oxidation product (34) can explain the formation of the quinone imine products (8) and (10). No carbon–carbon coupled products were isolated.