Abstract. Analogues of both the nonapeptides, bradykinin and bradykinin potentiating nonapeptide BPP 9α , were synthesized using HYCRAM™-technique. The bradykinin analogues were assembled by the Boc-, Ddz-and Fmoc-strategy starting with Boc-Arg(Aloc) 2 -OCr-OH, Ddz-Arg(Mtr)-OCr-OH and Fmoc-Arg(Mtr)-OCr-OH. While Boc-and Ddz-strategy provide peptides in good yield and purity, the Fmoc-strategy leads to a loss of peptide from resin. For simultaneous cleavage from HYCRAM™-resin and removal of Aloc-side chain protection optimized conditions for catalytic cleavage with Pd° were developed. As shown by the synthesis of BPP 9α analogues the HYCRAM™-linker and the chlorotrityl resin Solid phase syntheses of peptides with sensitive amino acids or sensitive pseudopeptide bonds require special linkers, which are stable under the conditions of coupling and deprotection and very smoothly to cleave without strong acidic or basic conditions. With the development of the hydroxycrotonoyl amino methyl linker (HYCRAM TM ) by Kunz et al. [1,2,3] and Birr [4, 5] a linker was found which fulfills these requirements in a good manner. The assembled peptides can be removed from the resin by treatment with Pd[P(C 6 H 5 ) 3 ] 4 as catalyst under nearly neutral conditions. Catalysts, scavallow the assembly of peptides with the C-terminal sequence Pro-Pro by preventing dioxopiperazine formation. Since the BPP 9α sequence contains the tripeptide Trp-X-Arg an intramolecular migration of the N G -protecting group to the indole ring under conditions used for its removal had to be avoided. By the use of HYCRAM™-linker in combination with Aloc protection for the guanidino group and Ddz for N α no modification of Trp occurred. HYCRAM™-technology in combination with Boc-, Ddz-or Aloc/All-protecting groups facilitates the synthesis of peptides with such very labile amino acids like cis-4-hydroxyproline. 1 ) Other abbreviations include: o-Aba; m-Aba, ortho, meta amino benzoic acid; Aloc, allyl oxycarbonyl; BK, bradykinin; Boc, tert-butyloxycarbonyl; BPP 9α , bradykinin potentiating peptide 9α (Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro); BOP, benzotriazole-1-yl-oxy-tris (dimethylamino) phosphonium hexafluorophosphate; Bu 3 SnH, tributyltin hydride; Bu
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