Mechanism of benzo-1,2,3,4-tetrazine 1-N-oxide formation

Benzo-1,2,3,4-tetrazine 1-N-oxide formation involves the intramolecular cyclization of 2-(tert-butyl-NNO-azoxy)phenyldiazonium tetrafluoroborates and the N→N migration of the tert-butyl group to afford 2-(tert-butyl)benzo-1,2,3,4-tetrazinium 4-N-oxides 3 followed by elimination of the tert-butyl group. Compounds 3 were hydrolysed to give a new heterocyclic system, viz. 2-alkyl-6-oxo-2,6-dihydrobenzo-1,2,3,4-tetrazine 4-N-oxides. For 2-(tert-butyl)-8-bromo-6-oxo-2,6-dihydrobenzo-1,2,3,4-tetrazine 4-N-oxide an X-ray diffraction study was carried out.