A double regio- and stereoselective glycosylation strategy for the synthesis of N-glycans |
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Authors: | Unverzagt Carlo Eller Steffen Mezzato Stefano Schuberth Ralf |
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Affiliation: | 1. Institut für Organische Chemie und Biochemie, Technische Universit?t München, Lichtenbergstrasse 4, 85748 Garching, Germany;2. Current address: Bioorganische Chemie, Universit?t Bayreuth, Geb?ude NW1, 95440 Bayreuth, Germany, Fax: (+49)?921‐55‐5365 |
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Abstract: | 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. |
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Keywords: | carbohydrates glycoproteins glycosylation oligosaccharides regioselectivity |
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