PEPTIDE DERIVATIVES AND PROCESSES FOR THEIR PREPARATION

摘要

Peptide ester and amide derivatives of the general formula I: (I) in which X is H or an acyl, A and B are structurally defined amino acid residues, n is an integer of from 1 to 3, Rl is H or a lower alkyl and either R2 or C is a defined optionally modified amino acid residue and the other is a lower alkoxyl, an amino group or a direct chemical bond, are converted under physiologic conditions, by enzymic hydrolysis in pathologically altered tissues and subsequent spontaneous cyclization, into pharmacodynamically active spirocyclic peptide derivatives of the general formula III, (III) in which R3 and R4 are H atoms, optionally substituted alkyl groups or jointly an aliphatic chain forming preferably a 2,5-piperazinedione ring, and hence can act as pro-farmaca (drug precursors) of prolonged biological effect. A process for the production of these derivatives is also disclosed.