2-Amino-4,4α-dihydro-4α,7-dimethyl-3H-phenoxazin-3-one as an unexpected product from reduction of 5-methyl-2-nitrophenol

Abstract

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-4,4α-dihydro-4α,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.