Oligosaccharides polymer-bound

In addition to well-resolved one-dimensional (ID) 1H and 13C spectra, which are usually sufficient for monitoring synthetic steps, HR-MAS techniques can be applied to two-dimensional (2D) homonuclear and heteronuclear experiments, which allow a wealth of structural information to be obtained. H,13C HMQC (heteronuclear multiple quantum coherence) spectra are particularly useful in the analysis of solid support-bound oligosaccharides, since the anomeric protons exhibit characteristic resonances. Such a spectrum of a polymer-bound trisaccharide glycal is shown in Figure 8.4. 

Trichloroacetimidates are widely used in oligosaccharide syntheses as anomeric leaving groups. They can also be applied under solid-phase conditions when the acceptor is attached to the resin. Glucose is bound to the solid support by functionalization of the anomeric center with a propanedithiol linker [2]. (l,6)-Glycosylation is achieved by selective deprotection of the primary hydroxyl group and coupling of the obtained polymer-bound acceptor 1... 

While precipitation / crystallisation is easily automated, dialysis and gel permeation require more laborious workup procedures. In addition, precipitation / crystallisation seems to be less predictive and reproducible. Notably, it has been shown with soluble polystyrenes in the synthesis of e.g. oligosaccharides that the yields of purified polymer-bound products decreased considerably as the oligosaccharide chain grew due to increased solubility of the sugar-polymer conjugate in polar solvents.13... 

Solid-phase Oligosaccharide Synthesis. Methanesulfonyl chloride resin 1 was used as an activating linker in the synthesis of various polymer-bound di and trisaccharides 2 (eq 1). The sulfonate linker proved stable to glycosidation and alcohol deprotection conditions, and nucleophilic displacement of 2 by Nal provided 6-iodosaccharides (eq 1). NaOAc and NaNs were also suitable nucleophiles for cleavage of the sulfonate linker. ... 

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