[1,4]Dithiino[2,3-c:5,6-c']bis[1,2,5]oxadiazole di-N-oxide: synthesis and oxidation to mono- and bis-S-oxides

[1,4]Dithiino[2,3-c:5,6-c']bis[1,2,5]oxadiazole di-N-oxide being an equilibrium mixture of two isomers was synthesized from 1,4-dithiane-2,3,5,6-tetraone tetraoxime and nitric acid; its oxidation to mono- and bis-S-oxides gave one isomer of each derivative.