Tricyclic heteroaromatic systems. Pyrazolo[3,4-c]quinolin-4-ones and pyrazolo[3,4-c]quinoline-1,4-diones: synthesis and benzodiazepine receptor activity.

Some pyrazolo[3,4-c]quinoline-4-ones 1-14 and pyrazolo[3,4-c]-quinoline-1,4-diones 15-17 were prepared and biologically evaluated for their binding at the benzodiazepine receptor (BZR) in rat cortical membranes. The moderate binding activity of 1-5, 7, 9-10, 13 is attributable to the lack of the optional proton acceptor at position-1, while the inactivity of the 1,4-dione derivatives 15-17 is due to the lack of the essential proton acceptor at position-3. These conclusions confirm the validity of our proposed pharmacophoric model.