Tricyclic heteroaromatic systems. Synthesis and benzodiazepine receptor affinity of 2-substituted-1-benzopyrano[3,4-d]oxazol-4-ones, -thiazol-4-ones, and -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. Benzodiazepine receptor (BZR) binding assays were performed on these series of tricyclic heteroaromatic systems. None of the tested compounds showed detectable 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 schematic representation of the interaction of these kinds of tricyclic heteroaromatic systems with the BZR recognition site, the nature of the optional a. proton acceptor is of significant importance in the receptor-ligand interaction. (C) 1998 Elsevier Science S.A. All rights reserved.