A Facile Synthesis of C-terminal Neoglycopeptides: Incorporation of Urea Moiety between Sugars and Peptides Employing Curtius Rearrangement

Abstract

Incorporation of urea moiety in the synthesis of C-terminal neoglycopeptides has been demonstrated through the reaction between suitably protected glycosylamine and Fmocpeptidyl isocyanates or carbamates. Curtius rearrangement has been made use off for the conversion of peptidyl acid azides in to corresponding isocyanates. The resulting C-terminal neoglycopeptidylureas have been isolated as stable solids which are fully characterized by 1 H NMR and mass spectroscopy.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

“…Side reactions avoided by using low concentrations of reagents. Biotinylated oligomannosylpeptoids To study binding to concanavalin A TOF (Yuasa, et al, 2007) C-Linked antifreeze glycopeptides TOF (DHB) Study of hydration for inhibition ice recrystallization (Czechura, et al, 2008) C-Terminal neoglycopeptidylureas TOF Incorporation of urea moiety between sugars and peptides employing Curtius rearrangement (Sureshbabu, et al, 2008) TOF Collagen type II analogues Studies on the interactions in the ternary Aq/glycopeptide/T-cell receptor complexes that activate T cells in autoimmune arthritis (Andersson, et al, 2007) TOF (DHB) Core 4 glycopeptide Benzyl protection. Microwave irradiation to dechlorinate Cl 3 CO (Ueki, et al, 2007) Core fucosylated and bisected glycans…”

Synthesis, Characterization, X-Ray Crystallography, and Antileishmanial Activities of N-Linked and O-Linked Glycopyranosides

“…In the case of glucosamine and galactosamine hydrochlorides, which already contain amino functionality, to ensure chemoselectivity in coupling with tartaric acid, a relative long route was adopted involving protecting the entire hydroxyl and amino functionalities on these sugars. Thus per acetylation [26], followed by anomeric bromination [27], azide formation [28] and reduction of azides afforded the target acetylated glycopyranosyl amines 4a-e.…”

Recent Developments in Neoglycopeptide Synthesis

“…Sureshbabu et al described the production of urea-linked glycopeptides in which C-terminal peptidyl isocyanates [25] and amino acid-derived oxazolidinone isocyanates [26] were obtained via Curtius rearrangement of the corresponding acid azides and subsequently trapped by glycosylamines (Scheme 11.5). This approach was further refined to a one-pot procedure, using Deoxo-Fluor and trimethylsilyl azide to generate the acid azide [27].…”

“…The isocyanates were also transformed to more stable yet equally reactive pentafluorophenyl carbamates before conversion to the ureas [25,26]. In subsequent reports, preactivation of the carboxy group was avoided by using diphenyl phosphoryl azide as an azido-transfer reagent [28].…”