RESUMO
A novel approach to the synthesis of Fmoc-protected neoglycopeptide building blocks is described. Oxidation of N-acetyl-D-glucosamine isonitrile afforded the corresponding highly reactive glycopyranosyl isocyanate, which reacted with amino acid derivatives to furnish the corresponding urea- and carbamate-tethered Fmoc-protected N-acetyl-D-glucosamine amino acid conjugates in good yields. [reaction: see text]
Assuntos
Aminoácidos/química , Carbamatos/química , Glucosamina/análogos & derivados , Glicopeptídeos/síntese química , Ureia/análogos & derivados , Carbamatos/síntese química , Catálise , Glucosamina/química , Glicopeptídeos/química , Estrutura Molecular , Ureia/síntese química , Ureia/químicaRESUMO
A new method for the synthesis of urea-linked disaccharides in aqueous media has been developed. The key feature of our approach is two strained Steyermark-type gluco- and galactopyranosyl oxazolidinones. Each oxazolidinone is attached to a pyranose ring in a di-equatorial trans-annulation framework. Reaction of these oxazolidinones with 4-aminohexopyranose in water proceeded smoothly to afford the urea-tethered cellobiose and lactose analogues. The galactose-type oxazolidinone proved to be more reactive than the glucose-type, which is explained by the presence of an axial hydroxy group at C4 in the former.