Stereoselective 11C Labeling of a “Native” Tetrapeptide by Using Asymmetric Phase-Transfer Catalyzed Alkylation Reactions

Aleksandra Pekošak*, Benjamin H. Rotstein, Thomas L. Collier, Albert D. Windhorst, Neil Vasdev, Alex J. Poot

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


The first 11C-labeled unmodified (“native”) peptide is described by alkylation of a tetrapeptide Schiff base, which was achieved by an automated five-step radiochemical reaction. In a proof-of-concept study, [11C]Phe-d-Trp-Lys-Thr was synthesized. This tetrapeptide is the essential pharmacophore of octreotide, an antagonist of somatostatin receptors. The asymmetric alkylation with chiral phase-transfer catalysts enabled direct labeling of a variety of isolated 11C-peptides in a highly stereoselective manner (94 % de) with acceptable radiochemical yields (9–10 %) and practical specific activities (15–35 GBq µmol–1 or 405–945 mCi µmol–1) at the end of synthesis. This novel methodology provides a powerful new radiosynthetic method to access novel, stereochemically pure carbon-11-labeled native small peptides ready for in vivo studies.

Original languageEnglish
Pages (from-to)1019-1024
Number of pages6
JournalEuropean Journal of Organic Chemistry
Issue number5
Publication statusPublished - 3 Feb 2017

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