Formation of Dihydrotriphenodioxazines and Dihydroisotriphenodioxazines by Acidic Treatment of Some Substituted 3H-Phenoxazin-3-ones: Isolation and Characterization. A New Perspective in the Chemistry of Ommochromes

Article abstract of DOI:10.1021/jo00169a006

Cleavage of the substituted 3H-phenoxazin-3-one system is observed in acidic medium.Isolation and characterization of 1,9-dicarbomethoxy-2-hydroxy-3H-phenoxazin-3-one (5a) and 1,8,13-tricarbomethoxy-7,14-dihydrotriphenodioxazine (6a), of 1,9-diacetyl-2-hydroxy-3H-phenoxazin-3-one (5b) and 1,8,13-triacetyl-7,14-dihydrotriphenodioxazine (6b), of 2,7-dicarbomethoxy-4-hydroxy-3H-phenoxazin-3-one (5c) and 3,8,13-tricarbomethoxy-7,14-dihydroisotriphenodioxazine (6c), and of 2,7-diacetyl-4-hydroxy-3H-phenoxazin-3-one (5d) and 3,8,13-triacetyl-7,14-dihydroisotriphenodioxazine (6d) from the treatment in methanol-0.2 N H2SO4 of 1,9-dicarbomethoxy-2-amino-3H-phenoxazin-3-one (4a), 1,9-diacetyl-2-amino-3H-phenoxazin-3-one (4b), 2,7-dicarbomethoxy-4-amino-3H-phenoxazin-3-one (4c), and 2,7-diacetyl-4-amino-3H-phenoxazin-3-one (4d), respectively, are reported.A probable mechanism for the formation of the reaction products is presented.