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
Jansze, S. M., Saggiomo, V., Marcelis, A. T. M., Lutz, M., & Velders, A. H. (2015). 2-Amino-4,4a-dihydro-4a,7-dimethyl-3H-phenoxazin-3-one as an unexpected product from reduction of 5-methyl-2-nitrophenol. Tetrahedron Letters, 56(9), 1060-1062. https://doi.org/10.1016/j.tetlet.2015.01.089