Synthesis and stability of 5-, 7- and 8-substituted benzo-1,2,3,5-tetrazepin-4-ones

Article abstract of DOI:10.3987/com-98-8108

In order to determine the effect of substituents on the stability of benzo-fused 1,2,3,5-tetrazepin-4-ones, 5-, 7- and 8-substituted derivatives (6a-d), and (10) were synthesized. The stability of the tetrazepinones increased with the electron withdrawing character of the substituents at the benzene ring. Bulky groups at the 5 position destabilize the tetrazepinone ring. The unstable tetrazepinones (6b, 10 and 14) decomposed in chloroform at room temperature to benzotriazole derivatives (11, 12 and 15). X-Ray diffraction of nitrobenzotetrazepinone (6d) showed that despite the elctron withdrawing effect of the nitro group para to the triazene chain, N3 exhibited a significant pyramidal character. In 6d, the 1,2,3,5-tetrazepinone cycle has an almost perfect seven-membered ring boat shape.