When attempting to synthesize symmetric 2,2'-dihydroxy-4,4'-dimethyl-azobenzene from 5-methyl-2-nitrophenol by reductive methods based on two literature procedures, an unexpected product was isolated in 30% yield. Full analysis by mass spectrometry, NMR spectroscopy, and single-crystal X-ray structure analysis, proved this product to be tricyclic 2-amino-4,4a-dihydro-4a,7-dimethyl-3H-phenoxazin-3-one. This Letter conveys a warning regarding reductive synthetic routes toward azobenzenes. We also present a novel reductive synthetic route for phenoxazines, an important class of tricyclic compounds.
- aromatic nitro-compounds
- phenoxazinone synthase