Abstract The course of the thermal decomposition of various 2-amino-3-substituted aziridino- 1, 4-naphthoquinones (Ia-g) was investigated. In all the cases, the thermal decomposition gave variable amounts of 2, 3-diamino-1, 4-naphthoquinone (II) and of substituted 1, 2, 3, 4, 5, 10-hexahydrobenzo [g] quinoxaline-5, 10-diones (IIIa-g) with complete stereospecificity. The decomposition of the aziridines Ib, f also gave significative amounts of 2-amino-3- ...