PROCESS FOR THE LOW-RACEMIZATION PREPARATION OF PEPTIDE INTERMEDIATES OF THE SYNTHESIS OF GONADORELIN AND GONADORELIN ANALOGS, AND NEW INTERMEDIATES FOR THIS PROCESS

摘要

The invention relates to a process for the preparation of peptides of the formula I U - A1 - A2 - A3 - A4 - A5 - X (I) in which U denotes a urethane protective group, A1 denotes Trp or D-Trp, A2 denotes Ser, Ala or Thr, A denotes Tyr or Phe, A4 denotes Gly, the residue of a D-amino acid or the residue of a D-amino acid derivative, A5 denotes Leu, N-methyl-Leu, N-ethyl-Leu, Ser(But), Cys(But), Asp(OBut), Glu(OBut), Orn(Boc) or Lys(Boc) and X denotes OBut or A6-Pro-Y, where A6 represents Arg, Orn, Lys or homoarginine, and Y repre-sents Gly-NH2, NH-NH-CO-NH2, (C1-C3)-alkylamino, cyclopropylamino, (C1-C3)-alkylamino which is substituted with hydroxyl or fluorine, or cycloalkylamino which is substituted with hydroxyl or fluorine, using tripeptides of the formula II, U - A1 - A2 - A3 - OH, in which the residues are defined as above. The invention also relates to peptides of the formula II as intermediates in this process.