The title compound was synthesized by stepwise solid-phase peptide synthesis, starting from the protected arginine linked to PAM resin (I). After deprotection of the Boc group of (I) with trifluoroacetic acid, coupling with (Boc)-tryptophan (II) in the presence of TBTU and diisopropylethylamine afforded the dipeptide resin (III). Sequential deprotection and coupling cycles with (Boc)-D-cyclohexylalanine (IV), (Boc)-proline (VI), (Boc)-ornithine (VIII), and (Fmoc)-phenylalanine (X) provided the resins (V), (VII), (IX) and (XI), respectively.

Cleavage from the resin (XI) using anhydrous HF in the presence of thiocresol furnished the linear peptide (XII). This was cyclized employing BOP and diisopropylethylamine in DMF to give the cyclic peptide (XIII). The Fmoc group of (XIII) was finally deprotected by means of piperidine in DMF.