A double regio- and stereoselective glycosylation strategy for the synthesis of N-glycans.
A building block approach for biantennary N-linked oligosaccharides from glycoproteins (N-glycans) has been developed. Starting from a core trisaccharide (beta-mannosyl chitobiose) containing a benzylidene-protected beta-mannoside, the attachment of the disaccharide building blocks for the antennae can be performed in a double regio- and stereoselective manner. A short synthesis of a GlcNPhtbeta1,2Man donor was developed. The benzylidene acetal moiety, as a minimal protection of the beta-mannoside, allows selective alpha-glycosylation at OH-3 of the 2,3-diol with GlcNbeta1,2Man trichloroacetimidate donors. Subsequent debenzylidenation leads to a 4,6-diol, which can be selectively extended at OH-6. Overreaction at OH-4 was generally low when phthalimido-protected donors were used. This general strategy represents a modular synthesis of N-glycans and their glycoconjugates.
Unverzagt
Carlo
C
Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany. carlo.unverzagt@uni-bayreuth.de
Eller
Steffen
S
Mezzato
Stefano
S
Schuberth
Ralf
R
D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000138:chemical synthesis* / Q000737:chemistry*; D006031:Glycosylation; D007096:Imidoesters / Q000737:chemistry; D008362:Mannosides / Q000737:chemistry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis; D013237:Stereoisomerism; D013379:Substrate Specificity
D006023:Glycoproteins; D007096:Imidoesters; D008362:Mannosides; D009844:Oligosaccharides