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Regiospecific anomerisation of acylated glycosyl azides and benzoylated disaccharides by using TiCl4.

Farrell, Mark
; 
Zhou, Jian
; 
Murphy, Paul V.
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Identifiers
http://hdl.handle.net/10379/4364
 https://doi.org/10.13025/15031
Publication Date
2013-10-25
Keywords
Anomerisation, Glycuronic acid, Lewis acids, Protecting groups, Pegioselectivity
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Article
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Citation
Farrell M, Zhou J, Murphy PV (2013) 'Regiospecific Anomerisation of Acylated Glycosyl Azides and Benzoylated Disaccharides by Using TiCl4'. Chemistry (Weinheim an der Bergstrasse, Germany), 19 (44):14836-14851.
Abstract
Chelation induced anomerisation is promoted when Lewis acids, such as TiCl4 or SnCl4 , coordinate to the pyranose ring oxygen atom and another site, giving rise to endocyclic cleavage and isomerisation to the more stable anomer. In this research regiospecific site-directed anomerisation is demonstrated. TiCl4 (2.5â equiv) was employed to induce anomerisation of 15 glycosyl azide and disaccharide substrates of low reactivity, and high yields (>75â %) and stereoselectivies (α/β>9:1) were achieved. The examples included glucopyranuronate, galactopyranuronate and mannopyranuronate as well as N-acetylated glucopyranuronate and galactopyranuronate derivatives. A disaccharide with the α1â 4 linkage found in polygalacturonan was included. The use of benzoylated saccharides was found to be important in disaccharide anomerisation as attempts to isomerise related acetyl protected and 2,3-carbonate protected derivatives were not successful.
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Publisher
Wiley
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Attribution-NonCommercial-NoDerivs 3.0 Ireland
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School of Biological and Chemical Sciences (Scholarly Articles)