Synthesis of Ureido-Linked Glycosylated Amino Acids from N ^α-Fmoc-Asp/Glu-5-oxazolidinones and Their Application to Neoglycopeptide Synthesis

Abstract

A simple route for the synthesis of ureido-linked glycosylated amino acids has been described. The key step involves the reaction of isocyanates derived from N a -Fmoc-Asp=Glu-5-oxazolidinones 1 with glycosyl amines followed by hydrolysis. The resulting ureido-linked glycosylated amino acids have been incorporated into peptides. The overall procedure is simple, high-yielding, and involves fewer steps.

Synthesis and characterization of poly(ethylene oxide)/polylactide/polylysine tri‐arm star copolymers for gene delivery

“…The macroinitiator mPEO‐S(Boc)‐OH was synthesized by the coupling of Boc‐protected serine to amine‐terminated PEO (mPEO‐NH 2 ) . The Boc group was chosen for compatibility with lactide polymerization conditions and for its ability to be removed without degradation of the polylactide block.…”

“…mPEO5k‐S(Boc)‐OH and mPEO2k‐S(Boc)‐OH were prepared by an identical procedure adapted from the literature . In a typical procedure, mPEO2k‐amine (1.01 g, 0.465 mmol), Boc‐Ser‐OH (145 mg, 0.706 mmol), HOBt• H 2 O (74 mg, 0.484 mmol), and EDC•HCl (93 mg, 0.485 mmol) were dissolved in CH 2 Cl 2 (40 mL) and the resulting solution was cooled to 4 °C in an ice bath.…”

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].…”

“…Scheme 11.5 Synthesis of urea-linked glycosides[26]. Scheme 11.4 Synthesis of S-glycosides via Ferrier reaction[21].…”