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Nickel-catalyzed stereoselective glycosylation with C(2)-N-substituted benzylidene D-glucosamine and galactosamine trichloroacetimidates for the formation of 1,2-cis-2-amino glycosides. Applications to the synthesis of heparin disaccharides, GPI anchor pseudodisaccharides, and α-GalNAc.
Mensah, Enoch A; Yu, Fei; Nguyen, Hien M.
Afiliação
  • Mensah EA; Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
J Am Chem Soc ; 132(40): 14288-302, 2010 Oct 13.
Article em En | MEDLINE | ID: mdl-20860359
The 1,2-cis-2-amino glycosides are key components found within a variety of biologically important oligosaccharides and glycopeptides. Although there are remarkable advances in the synthesis of 1,2-cis-2-amino glycosides, disadvantages of the current state-of-the-art methods include limited substrate scope, low yields, long reaction times, and anomeric mixtures. We have developed a novel method for the synthesis of 1,2-cis-2-amino glycosides via nickel-catalyzed α-selective glycosylation with C(2)-N-substituted benzylidene D-glucosamine and galactosamine trichloroacetimidates. These glycosyl donors are capable of coupling to a wide variety of alcohols to provide glycoconjugates in high yields with excellent levels of α-selectivity. Additionally, only a substoichiometric amount of nickel (5-10 mol %) is required for the reaction to occur at 25 °C. The current nickel method relies on the nature of the nickel-ligand complex to control the α-selectivity. The reactive sites of the nucleophiles or the nature of the protecting groups have little effect on the α-selectivity. This methodology has also been successfully applied to both disaccharide donors and acceptors to provide the corresponding oligosaccharides in high yields and α-selectivity. The efficacy of the nickel procedure has been further applied toward the preparation of heparin disaccharides, GPI anchor pseudodisaccharides, and α-GluNAc/GalNAc. Mechanistic studies suggest that the presence of the substituted benzylidene functionality at the C(2)-amino position of glycosyl donors is crucial for the high α-selectivity observed in the coupling products. Additionally, the α-orientation of the C(1)-trichloroacetimidate group on glycosyl donors is necessary for the coupling process to occur.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Acetilgalactosamina / Compostos de Benzilideno / Heparina / Glicosilfosfatidilinositóis / Galactosamina / Glucosamina / Níquel Idioma: En Ano de publicação: 2010 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Acetilgalactosamina / Compostos de Benzilideno / Heparina / Glicosilfosfatidilinositóis / Galactosamina / Glucosamina / Níquel Idioma: En Ano de publicação: 2010 Tipo de documento: Article