Hypotensive activity is exhibited by compounds having the formula ##STR1## and pharmaceutically acceptable salts thereof wherein R.sub.1 is hydrogen or alkyl;R.sub.2 and R.sub.3 are each independently phenyl, substituted phenyl, cycloalkyl, or R.sub.2 is hydrogen and R.sub.3 is heteroaryl;R.sub.4 and R.sub.5 are the same or different and each is hydrogen, hydroxy, alkoxy, alkanoyl or alkyl;R.sub.6 is hydrogen or alkyl; andn is 1, 2, 3 or 4; with the proviso that if R.sub.2 and R.sub.3 are each phenyl, at least one of R.sub.1, R.sub.4, R.sub.5 and R.sub.6 is other than hydrogen.