TRICYCLIC HETEROAROMATIC SYSTEMS - SYNTHESIS AND BENZODIAZEPINE RECEPTOR AFFINITY OF 2-SUBSTITUTED-1-BENZOPYRANO[3,4-D]OXAZOL-4-ONES, 2-SUBSTITUTED-1-BENZOPYRANO[3,4-D]-THIAZOL-4-ONES, AND 2-SUBSTITUTED-1-BENZOPYRANO[3,4-D]-IMIDAZOL-4-ONES

A number of 2-aryl-substituted-1-benzopyrano[3,4-d] oxazol-4-ones 1, - thiazol-4-ones 2 and -imidazol-4-ones 3 were synthesized. Benzodiazepi ne receptor (BZR) binding assays were performed on these series of tri cyclic heteroaromatic systems. None of the tested compounds showed det ectable affinity for BZR. Comparative structure-activity relationship analysis between the reported compounds and some known BZR ligands of similar size and shape revealed that, according to a two-dimensional s chematic representation of the interaction of these kinds of tricyclic heteroaromatic systems with the BZR recognition site, the nature of t he optional a. proton acceptor is of significant importance in the rec eptor-ligand interaction. (C) 1998 Elsevier Science S.A. All rights re served.