The invention relates to compounds of formula (I), wherein Z represents a hydrocarbon with 2 to 28 C atoms, wherein Z can also comprise elements N, O, P, S, Si and halogen as heteroatoms, R.sup.1 and R.sup.2 are identical or different sulfur protecting groups, wherein both S atoms can also form a disulfide bridge and in said case R.sup.1 and R.sup.2 are not present; protecting group Y.sup.1 represents protecting group NH, protecting group NR.sup.4, protecting group O, CONH protecting group, protecting group OOC, protecting group S--S, --CH(protecting group O).sub.2 or --CR.sup.5(protecting group O).sub.2 or protecting group S; Y.sup.2 represents --OH, --NH.sub.2, --NHR.sup.3, --NR.sup.3R.sup.4, --COOH, --COCI, --COOCO--R.sup.6, --CONH.sub.2, --CONHR.sup.3, --COOR.sup.3, --SO.sub.3H, --SO.sub.3CI, --SH, --S--SR.sup.3, --CHO, --COR.sup.3, --C.sub.2H.sub.3O, halogen, --N.sub.3, --NH--NH.sub.2, --NCO, --NCS, wherein R.sup.3 represents alkyl, heteroalkyl, aryl, cycloalkyl or a protecting group, wherein R.sup.3 can be identical or different in groups Y.sup.1 and Y.sup.2, R.sup.4 is s protecting group, wherein R.sup.4 can be identical or different in groups Y.sup.1 and Y.sup.2, and wherein R.sup.4 and R.sup.3 can be identical or different, R.sup.5 represents alkyl, aryl or cycloalkyl, wherein R.sup.5 can be identical or different in groups Y.sup.1 and Y.sup.2 and R.sup.6 represents alkyl, heteroalkyl, aryl or cycloalkyl, wherein R.sup.6 can be identical or different in groups Y.sup.1 and Y.sup.2, wherein Y.sup.2 can also represent a group of formula (II) or formula (III), wherein X.sup.1 represents halogen or a substituted amine, X.sup.2 represents an alkyl, alkoxy, aryloxy radical or a cyano derivative of an alkyl, alkoxy, aryloxy radical, X.sup.3 represents halogen, an amino function or oxygen and X.sup.4 represents an alkyl, alkoxy, aryloxy radical or X.sup.4 equals H if X.sup.3=oxygen. ##STR00001##