Patent ID: 8741834

Claim:
A compound of the formula (I) in which R PD is a group of the formula in which # means the point of linkage to the respective O atom, L 1 is straight-chain (C2-C4)-alkanediyl, L 2 is straight-chain (C1-C3)-alkanediyl, R 1 and R 3 are identical or different and are independently of one another hydrogen or the side group of a natural α-amino acid or its homologs or isomers, R 2 and R 4 are independently of one another hydrogen or methyl or R 1 and R 2 or R 3 and R 4 are in each case linked to one another and, together with the carbon atom to which they are jointly attached, form a 3- to 6-membered saturated carbocycle, R 5 is hydrogen or (C1-C4)-alkyl or R 5 is linked to R 1 and both, together with the atoms to which they are attached, form a pyrrolidine or piperidine ring, R 6 and R 7 are identical or different and independently of one another are hydrogen or (C 1 -C 4 )-alkyl which may be substituted by hydroxyl, (C 1 -C 4 )-alkoxy, amino, mono-(C 1 -C 4 )-alkylamino or di-(C 1 -C 4 )-alkylamino or R 6 and R 7 are linked to one another and, together with the nitrogen atom to which they are attached, form a 5- or 6-membered saturated heterocycle which may comprise a further ring heteroatom from the series consisting of N and O, and may be substituted one or two times, identically or differently, by (C 1 -C 4 )-alkyl, amino, hydroxyl and/or (C 1 -C 4 )-alkoxy, or R 6 is linked to R 3 and both, together with the atoms to which they are attached, form a pyrrolidine or piperidine ring and R 8 is hydrogen or carboxyl, and the salts thereof.