Synthesis and evaluation of pharmacological properties of novel annelated 2,3-benzodiazepine derivatives

New cyclofunctionalized 2,3-benzodiazepines characterized by a triazolone or triazindione ring fused on the "c" edge of the heptatomic nucleus have been prepared. These compounds were evaluated as potential anticonvulsant agents, and some of them proved to be more potent noncompetitive 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionate (AMPA) receptor antagonists. In particular, 8,9-dimethoxy-6-(4-bromophenyl)-11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepin-3(2H)-one (5b) was almost 10-fold more active than GYKI-52466 and 3.5-fold more active than Talampanel. Furthermore, 5b potently reduced AMPA-evoked currents in electrophysiological experiments.