Tricyclic Heteroaromatic Systems. 1,2,4-Triazolo[4,3-a]quinoxalines and 1,2,4-Triazino[4,3-a]quinoxalines: Synthesis and Central Benzodiazepine Receptor Activity.

Some 1,2,4-triazolo[4,3-a)quinoxalines 1-10, and 1,2,4-triazino[4,3-a(quinoxalines 11-12 were prepared and biologically evaluated for their binding at the benzodiazepine receptor (BZR) in rat cortical membranes. We BZR affinity of 1-10 demonstrates that the presence of a proton acceptor at position-1 is important for the potency of a BZR ligand. On the other hand, the BZR inactivity of the 1,2,5-trione derivatives 11-12 shows that the right collocation of the essential L. 2 lipophilic substituent is of paramount importance for receptor-ligand interaction.