Novel compounds of the general formula I ##STR1## where X is hydrogen, nitro or unsubstituted or substituted alkyl, alkenyl, cycloalkyl, aryl or hetaryl, Y is cyano, nitro, alkanoyl, aroyl, alkylsulfonyl, arylsulfonyl, carboxyl, a carboxylic ester group or unsubstituted or substituted carbamyl, R is unsubstituted or substituted alkyl or aryl, R.sup.1 is hydrogen or R.sup.2, and R.sup.2 is unsubstituted or substituted alkyl, alkenyl, cycloalkyl, aralkyl or aryl, are useful for dyeing textile fibers, in particular polyesters.