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