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Preparation of the β3-Homoselenocysteine Derivatives Fmoc-β3hSec(PMB)-OH and Boc-β3hSec(PMB)-OH for Solution and Solid-Phase-Peptide Synthesis and Selenoligation

✍ Scribed by Oliver Flögel; Giulio Casi; Donald Hilvert; Dieter Seebach

Publisher
John Wiley and Sons
Year
2007
Tongue
German
Weight
319 KB
Volume
90
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The title compounds, 4 and 7, have been prepared from the corresponding α‐amino acid derivative selenocystine (1) by the following sequence of steps: cleavage of the SeSe bond with NaBH~4~, p‐methoxybenzyl (PMB) protection of the SeH group, Fmoc or Boc protection at the N‐atom and Arndt–Eistert homologation (Schemes 1 and 2). A β^3^‐heptapeptide 8 with an N‐terminal β^3^‐hSec(PMB) residue was synthesized on Rink amide AM resin and deprotected (‘in air’) to give the corresponding diselenide 9, which, in turn, was coupled with a β^3^‐tetrapeptide thiol ester 10 by a seleno‐ligation. The product β^3^‐undecapeptide was identified as its diselenide and its mixed selenosulfide with thiophenol (Scheme 3). The differences between α‐ and β‐Sec derivatives are discussed.

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Preparation of the β2-Homoselenocysteine
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Preparation of (S,S)-Fmoc-β2hIle-OH, (S)
Preparation of (S,S)-Fmoc-β2hIle-OH, (S)-Fmoc-β2hMet-OH, and (S)-Fmoc-β2hTyr(tBu)-OH for Solid-Phase Syntheses of β2- and β2/β3-Peptides
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