Other 6-membered heterocycles R 0670 Annulated Benzotetrazine 1,3-Dioxides. Part 1. [1,2,5]Oxadiazolo[3,4-f][1,2,3,4]benzotetrazine 2,4,7-and 2,4,9-Trioxides. -Thermolysis of the benzotetrazine (II) results in a ring closure to a furoxane existing as 1:1 mixture of isomers (III) and (IV) at room temperature. On heating to 100°C the signals from the isomers coalesce in the 1 H NMR spectra; the original spectral pattern returns upon cooling. -(SMIRNOV, O. Y.; TYURIN, A. Y.; CHURAKOV*, A. M.; STRELENKO, Y. A.; TARTAKOVSKY, V. A.; Russ.