1-Azaanthracene-2,5,8-triones and 1,8-diazaanthracene-2,7,8,10-tetraones, Which are structurally related to diazaquinomycin, are prepared by functionalization of azaanthraquinone N-oxides. The complete procedure implies a Diels-Alder reaction as a key step, followed by N-oxidation and treatment of the N-oxides with benzoyl or tosyl chlorides in the presence of water.
A procedure is described for the efficient N-oxidation of heterocyclic quinones, which represents a considerable improvement over previous, multi-step methods.