Abstract: Compounds of Formula I: ##STR1## where R.sup.5 is a group selected from Formulae (a), (b), (c) and (d): ##STR2## and the pharmaceutically acceptable salts and N-oxides thereof, are .alpha..sub.1 -adrenergic receptor antagonists useful for the treatment of diseases involving directly or indirectly an obstruction of the lower urinary tract, such as benign prostatic hyperplasia.

Abstract: Disclosed herein are compounds of the formula:R.sup.1 CH.sub.2 CH(X)CH(Y)CH(Z)CHR.sup.2 C(O)NHCHR.sup.3 CH(OH)CH(OH)R.sup.4wherein R.sup.1 is a terminal unit, for example lower cycloalkyl or phenyl; R.sup.2 is, for example, an optionally substituted alkyl, cycloalkylmethyl, benzyl, 4-imidazolylmethyl, 2-thienylmethyl or 4-thiazolylmethyl; R.sup.3 is alkyl, cycloalkylmethyl or an optionally substituted benzyl; R.sup.4 is alkyl or cycloalkyl; and X and Y each is hydroxy and Z is hydrogen, or X and Z each is hydroxy and Y is hydrogen; with the provisos that (a) the carbon atom bearing R.sup.2 has the "R" configuration except when R.sup.2 is 2-thienylmethyl or 2-thiazolylmethyl, X and Y each is hydroxy and Z is hydrogen, then the carbon atom bearing R.sup.2 has the "S" configuration; (b) the carbon atoms bearing R.sup.3 and R.sup.4 each has the "S" configuration; and (c) the carbon atom located between the last-said two carbon atoms has the "R" configuration.