Abstract: Compounds of the formula I ##STR1## in which n denotes 0-3,R.sup.1 and R.sup.1' are the same or different and denote hydrogen, alkyl or alkenyl, phenyl or benzyl, each substituted as desired;R.sup.2 denotes hydrogen, alkyl or alkenyl;R.sup.3 denotes hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl or aminoalkyl, alkanoylaminoalkyl, guanidinoalkyl, imidazolylalkyl, indolylalkyl, mercaptoalkyl or alkylthioalkyl, phenylalkyl, hydroxyphenylalkyl, phenoxyalkyl or phenylthioalkyl, or R.sup.2 and R.sup.3, together with the C and N atoms carrying them, denote a saturated or unsaturated 4- to 8-membered monocyclic or 8- to 10-membered bicyclic isocycle or heterocycle, optionally monosubstituted or disubstituted by hydroxyl, alkoxy having 1 to 3 C atoms or alkyl,R.sup.4 denotes hydrogen, alkyl, alkenyl, alkadienyl, alkinyl, alkeninyl or alkadiinyl, cycloalkyl, phenyl, benzyl, phenethyl or phenylpropyl, each of which can be optionally monosubstituted or disubstituted;R.sup.5 denotes hydrogen or alkyl, hydroxyl or alkoxy andR.