Compounds having the formula
and pharmaceutically acceptable salts thereof wherein X is a single bond, O, CO, S, NH or N(lower alkyl); Y is O, S or NCN; and R¹ to R5' are as defined herein. These compounds have potassium channel activating activity and are useful, therefore for example, as cardiovascular agents.
Compounds having the formula ##STR1## and pharmaceutically acceptable salts thereof wherein X is a single bond, O, CO, S, NH or N(lower alkyl); Y is O, S or NCN; and R.sup.1 to R.sup.5' are as defined herein. These compounds have potassium channel activating activity and are useful, therefore for example, as cardiovascular agents.