Vasodilating activity is exhibited by compounds having the formula ##STR1## and the pharmaceutically acceptable salts thereof, wherein X is --CH.sub.2 -- or --S--;R.sub.1 is ##STR2## or --O--Y.sub.3 ; R.sub.2 is heterocyclo or heteroaryl;R.sub.3 and R.sub.4 are each independently hydrogen, halogen, alkyl, alkoxy, aryloxy, arylalkoxy, arylalkyl, cyano, hydroxy, alkanoyloxy, ##STR3## fluoro-substituted alkoxy, fluoro-substituted alkyl, (cycloalkyl)alkoxy, --NO.sub.2, --NY.sub.10 Y.sub.11, --S(O).sub.k alkyl, --S(O).sub.k aryl ##STR4## n is 0, 1, 2 or 3; m is 0, 1, 2 or 3;k is 0, 1 or 2;Y.sub.1 and Y.sub.2 are each independently hydrogen or alkyl; or Y.sub.1 is hydrogen and Y.sub.2 is alkenyl, alkynyl, aryl, heteroaryl, or cycloalkyl; or Y.sub.1 and Y.sub.2, together with the carbon atom to which they are attached, are cycloalkyl;Y.sub.3 is hydrogen, alkyl, alkanoyl, alkenyl, arylcarbonyl, heteroarylcarbonyl, or ##STR5## Y.sub.8 and Y.sub.9 are each independently hydrogen, alkyl, aryl, or heteroaryl; or Y.sub.8 and Y.sub.9, together with the nitrogen atom to which they are attached, are pyrrolidinyl, piperidinyl or morpholinyl;Y.sub.10 and Y.sub.11 are each independently hydrogen, alkyl, alkanoyl, arylcarbonyl, heteroarylcarbonyl, or ##STR6## Y.sub.12 is hydroxy, alkoxy, aryloxy, amino, alkylamino, or dialkylamino; andY.sub.13 is alkyl, alkoxy or aryloxy.