Conformational analysis, molecular modeling and quantitative structure-activity relationships studies of 2,4-diamino-6,7-dimethoxy-2-substituted quinazoline α1-adrenergic antagonists

Conformational analysis (AM1), modeling of the molecular shape (QUANTA 3.0) and quantitative structure-activity relationship analysis were done on a set of 16 2,4-diamino-6,7-dimethoxy-2-substituted quinazoline alpha-1-adrenoceptor antagonists (prazosin analogs). The results obtained show that the 2-substituents of the analogs considered are quite flexible. Furthermore, they suggest that, once the electronic requirements of the common quinazoline moiety are satisfied, the binding affinities are modulated by the molecular shape of the quinazoline 2-substituent, through the optimization of both dispersive and steric interactions and the hydrophobic contribution.