Transformations of 2-substituted 1-dialkylaminoanthraquinones. A reinvestigation

Abstract

The thermal and photolytic transformations of 2-acylamino-1 -dialkylaminoanthraquinones have been reinvestigated and shown to give in appropriate cases (i)N-acyldihydroimidazoanthraquinones and not 1-dialkylamino-2-oxaziridinylanthraquinones as suggested recently; or (ii) 1,2-dimethylimidazoanthraquinones and not 1-methyl-imidazoanthraquinones. The corresponding cyclisations of 2-amino-1-dialkylaminoanthraquinones give rise to two products: the imidazoanthraquinone and, surprisingly, 2-aminoanthraquinone. The reactions are rationalised mechanistically.