The invention relates to compounds of the formula ##STR1## in which A denotes an optionally substituted radical from the series comprising alkyl, acyl, cycloalkyl, aryl and heteroaryl; A.sup.1 represents CO, CS, C.dbd.NH, CN-alkyl, CN--O-alkyl, SO, optionally substituted CH.sub.2 or a bond; A.sup.2 represents NH, NCH.sub.3, O, CH.sub.2 or a bond; E represents CHOH, CO, SO or optionally N-substituted C.dbd.NH; A.sup.3 represents O, NH, NCH.sub.3 or a bond; R.sup.4 denotes an optionally substituted radical from the series comprising alkyl, cycloalkyl, aryl and heteroaryl; and R.sup.8 denotes hydrogen or optionally substituted alkyl, to a process for their preparation, and to their use as inhibitors of prolyl hydroxylase.