Synthesis of 1,2,3,4‐Tetrazine 1,3‐Dioxides Annulated with 1,3 a,4,6 a‐Tetraazapentalene Systems

A synthetic approach to 5,11‐dehydro‐5H,11H‐[1,2,3,4]tetrazino[5′,6′:4,5][1,2,3]triazolo[2,1‐a][1,2,3]benzotriazole 1,3‐dioxide (5) and 5,11‐dehydro‐5H,11H‐[1,2,3,4]tetrazino‐[5′,6′:4,5][1,2,3]triazolo[2,1‐a][1,2,3]benzotriazole 2,4‐dioxide (6) was developed. These ring systems are the first in which a 1,2,3,4‐tetrazine 1,3‐dioxide ring is directly fused with 1,3a,4,6a‐tetraazapentalene moiety. The synthesis started from (tert‐butyl‐NNO‐azoxy)acetonitrile (7) and involved the closure of the 1,2,3,4‐tetrazine 1,3‐dioxide ring first and then formation of the tetraazapentalene ring. The derivatives of ring systems 5 and 6 nitrated at the benzene ring were also obtained. The structures of the compounds synthesized have been confirmed by NMR spectroscopy and X‐ray diffraction studies.