Benzo-1,2,3,4-tetrazine 1,3-Dioxides: Synthesis and NMR Study

Abstract

Benzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) represent fairly stable high-nitrogen systems, incorporating two head-to-tail linked azoxy groups. The synthetic pathway to these heterocycles suggested the use of the tert-butyl-NNO-azoxy group as a building block, allowing the first azoxy group to be incorporated into the ring. The second azoxy group was added with the help of the oxodiazonium ion (−N=N=O+) or its synthetic equivalent. This could be generated by two new methods. The first of these involved treatment of N-nitroamines with nitrating agents, and the second treatment of diazonium salts with peracids in the presence of a base. The proposed key stage in the tetrazine 1,3-bis(N-oxide) ring formation is the reaction between the oxodiazonium ion and the distal nitrogen atom of the tert-butyl-NNO-azoxy group, followed by elimination of the tert-butyl cation. The syntheses of bromo-BTDOs 3b−f and nitro-BTDOs 4a−c are described. The BTDOs were characterized by NMR, including 14N and 15N experiments. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)