this invention relates to certain novel compounds and derivatives thereof , their synthesis , and their use as selective alpha 1a adrenergic receptor antagonists . one application of these compounds is in the treatment of benign prostatic hyperplasia . these componds are selective in their ability to relax smooth muscle tissue enriched in the alpha 1a receptor subtype without at the same time inducing hypotension . one such tissue is found surrounding the urethral lining . therefore , one utility of the instant compounds is to provide acute relief to males suffering from benign prostatic hyperplasia , by permitting less hindered urine flow . another utility of the instant compounds is provided by combination with a human 5 - alpha reductase inhibitory compound , such that both acute and chronic relief from the effects of benign prostatic hyperplasia are achieved .