[1,2,5]Oxadiazolo[3,4-d]pyridazine 1,5,6-trioxides: efficient synthesis via the reaction of 3,4-bis(hydroxyimino)methyl)-1,2,5-oxadiazole 2-oxides with a mixture of concentrated nitric and trifluoroacetic acids and structural characterization

• Published in: Tetrahedron letters 2018-08, Vol.59 (32), p.3143-3146
• Main Authors: Ogurtsov, Vladimir A., Dorovatovskii, Pavel V., Zubavichus, Yan V., Khrustalev, Victor N., Fakhrutdinov, Artem N., Zlotin, Sergei G., Rakitin, Oleg A.
• Format: Article
• Language: English
• Subjects: 3,4-Bis(hydroxyimino)methyl)-1,2,5-oxadiazole 2-oxides; [1,2,5]Oxadiazolo[3,4-d]pyridazine 1,5,6-trioxides; Intermolecular interactions; Nitric acid; Synchrotron X-ray diffraction
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2018.07.015

[Display omitted] •An efficient synthesis of [1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxides.•4,7-Dinitro[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide – high energy compound.•Unusually long intracyclic NN bond of 1.668(5) Å in organic molecule.•A mixture of concentrated nitric and trifluoroacetic acids as oxidizer. An efficient synthesis of [1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxides (1) from 3,4-bis(hydroxyimino)methyl)-1,2,5-oxadiazole 2-oxides using a mixture of concentrated nitric and trifluoroacetic acids has been developed. The scope of the unconventional reaction was established. The 4,7-dinitro[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide 1f represents a new high energy compound, unfortunately with low thermal stability. The parent [1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide 1c was studied by single-crystal X-ray diffraction analysis which revealed a planar molecule with an unusually long intracyclic NN bond of 1.668(5) Å and unexpected exo-cyclic bond angles at the nitroxyl nitrogen atoms. In the crystal, the molecules of 1c are bound to each other by strong π-π stacking and CH⋯O hydrogen bonding interactions into a three-dimensional framework that results in a high crystal density of 1.833 gcm−3.