Following synthesis, quantitative removal of the Alloc group allows conversion to the active N-acyl-benzimidazolinone (Nbz) species, which may be purified and converted in situ to thioester under ligation conditions. This method is compatible …

The use of Fmoc solid-phase peptide synthesis (Fmoc-SPPS) to obtain α-thioester peptides requires the development of novel strategies to overcome the lability of the thioester bond toward piperidine Fmoc-removal conditions.

Starting with Rink-PEG-PS resin (0.2 mmol/g, ABI), 3-(Fmoc)-4-diaminobenzoic acid (Fmoc-Dbz) was coupled and the Fmoc group deprotected with 20% piperidine. Notably, after acylation, the free amino group in position 3 or 4 becomes hindered/deactivated and does …

Herein, we report a traceless ligation at Val-Xaa sites under mild thiol additive-free reaction conditions, whereby the introduction of β-mercaptan on the C-terminal valine residue effectively activates the otherwise unreactive N-acyl-benzimidazolinone (Nbz), and enables the use of a one-pot ligation–desulfurization strategy to generate the ...

Apr 8, 2013 · We describe herein the identification of epimerization-free conditions for the synthesis of peptide salicylaldehyde esters via Fmoc-SPPS, and the successful ligation of these substrates with unprotected N-terminal Ser or Thr peptide fragments.

Oct 26, 2011 · The recent N-acylurea approach to thioester synthesis relies on the deactivation of one amine of 3,4-diaminobenzoic acid (Dbz) during Fmoc SPPS. Here, we demonstrate that this approach results in the formation of side products through the over-acylation of Dbz, particularly when applied to Gly-rich sequences.

Mar 7, 2020 · Synthesis of α-thioester peptides by Fmoc chemistry using the Nbz/MeNbz strategy: (a) coupling of Gly, (b) coupling of the Fmoc-Dbz/MeDbz linker, (c) coupling of the C-terminal residue (Fmoc-aa 1), (d) chain elongation, (e) activation with p-nitrophenylchloroformate , (f) base induced cyclization to render the resin bound N-acylurea peptide ...

Oct 1, 2018 · In this protocol, o-aminoanilide 1 is efficiently transformed into N-acyl-benzimidazolinone (Nbz) 2 by acylation with 4-nitrophenyl chloroformate and cyclization. This Nbz leaving group can tolerate the trifluoroacetic acid (TFA) cocktail used to deprotect the peptide and cleave it from the resin.

Treatment of the Nbz resin with TFA releases the fully deprotected peptide-Nbz, which can be used directly in the NCL reaction. The Nbz peptide is obtained as a mixture of regioisomers.

Sep 12, 2011 · Following synthesis, quantitative removal of the Alloc group allows conversion to the active N‐acyl‐benzimidazolinone (Nbz) species, which can be purified and converted in situ to thioester under ligation conditions. This method is compatible with the automated preparation of peptide–Nbz conjugates.