Substituted 1,2,3-triazolo[1,5-a]quinazolines: synthesis and binding to benzodiazepine and adenosine receptors

This paper reports the synthesis and evaluation of the biological affinity towards benzodiazepine and A 1 and A 2A adenosine receptors of some 3-ethoxycarbonyl or 3-phenyl-substituted 1,2,3-triazolo[1,5-a]quinazolines. Starting from the appropriate chloro-substituted phenylazides, the series of 7 or 8 chloro-substituted triazoloquinazolines were prepared. Nitration reactions of the triazoloquinazoline ring and chlorination reactions of the hydroxyl group in the 5 position of the same ring are also reported. By nucleophilic displacement of halogen, the corresponding 5-amino derivatives and some analogous derivatives bearing cyclohexylamino and p-toluidino substituents were obtained. The binding assays showed a generalized decrease in the affinity towards the benzodiazepine receptors and confirmed a moderate affinity towards the A 1 adenosine receptors in comparison with the previously studied triazoloquinazoline derivatives.