On the preparation of amine N-oxides by using dioxiranes

The reaction of heterocyclic aromatic amines, anilines and tertiary amines with dimethyldioxirane (DMD) was examined. Treatment of heterocyclic aromatic amines and anilines with a slight excess of DMD at 0 degrees C afforded the corresponding N-oxides in quantitative conversion yields. in addition, the oxidation was chemoselective in the presence of carbon-carbon double bonds. On the other hand, most of the tertiary amines assayed did afford also quantitative yields of the corresponding N-oxides, although reaction conditions, in particular regarding the amount of DMD required, depended on each substrate. Additional studies carried out on selected substrates suggested that certain N-oxides derived from tertiary amines deactivate DMD. (C) 1997 Elsevier Science Ltd.