A new cyclic octreotide-like octapeptide was prepared by incorporation of an unnatural tetrazolyl amino acid, an analog of Fmoc-L-lysine, into the peptide chain. The new tetrazolyl amino acid, (S)-2-{[2-(9H-fluoren- 9-yl)acetoxy]amino}-6-(1H-tetrazol-1-yl)hexanoic acid, was obtained by azidation of Fmoc-L-lysine trifluoroacetate with sodium azide in the presence of triethyl orthoformate in glacial acetic acid. The linear peptide sequence was prepared using efficient Fmoc/t-Bu solid-phase peptide synthesis (SPPS). Cyclization of the octapeptide was carried out via oxidation with iodine. The structure and purity of the cyclic octapeptide were confirmed by LC–MS, MALDI-TOF MS/MS analysis as well as 1D/2D 1H and 13C NMR spectroscopy.
Original languageEnglish
Pages (from-to)5041-5046
JournalTetrahedron Letters
Volume55
Issue number36
DOIs
StatePublished - 2014
Externally publishedYes

    Research areas

  • Unnatural amino acid 1H-Tetrazole L-Lysine Cyclic peptides Somatostatin analogs

ID: 5710391