Described are compounds of the formula ##STR1## wherein R is hydrogen, lower alkyl, halo, cyano, hydroxy, amino, lower alkylamino, --CH.sub.2 NH.sub.2, CH.sub.2 OH or COOR"; R' is hydrogen, lower cycloalkyl or lower alkyl; R" is lower alkyl or --CH.sub.2 Ar wherein Ar is phenyl, substituted phenyl, furan or thiophene; R'" is COOR", ##STR2## and x is oxygen or nitrogen; or a pharmaceutically acceptable salt thereof and their use in the treatment of impaired ventricular myocardial contractility. The compounds exhibit cardiotonic activity.