Chromatography methyl glycosides

A detailed study of the methyl glycosidation of the four aldopentoses has been made by Bishop and Cooper,16 42 with the aid of gas chromatography of the esters of the resulting pentofuranosides and pentopyranosides. Three competing reactions were established for the formation of the furanosides (1) an irreversible formation of furanosides from the free sugars (2) an anomerization of the furanosides and (3) conversion of the furanosides into the pyranosides. (A fourth reaction, anomerization of the pyranosides, will not be considered here.)... 

Conchie and Percival97 found that the direct methylation of fucoidin with dimethyl sulfate and sodium hydroxide was more satisfactory than the simultaneous deacetylation and methylation of its acetyl derivative. Methylated fucoidin was hydrolyzed and the products were converted to their methyl glycosides. By chromatography on alumina there were isolated methyl L-fucosides (about 20%), methyl 3-methyl-L-fucosides (57%) and methyl 2,3-dimethyl-L-fucosides (20%). 

Gas-Uquid chromatography has been used for the separation of methylated glycosides. ... 

After their isolation by chromatographic techniques (anion-exchange chromatography, size exclusion, etc.), different analytical methodologies have been used to identify and quantify the polysaccharides in wine the most commonly used being the traditional methylation analysis followed by GC-MS (Doco and Bril-louet 1993). Polysaccharides have also been determined after solvolysis with anhydrous methanol containing HCl by GC-MS of their per-G-trimethylsilylated methyl glycosides (Vidal et al. 2003). Other techniques such as Fourier transform infrared spectroscopy (FTIR) have been more recently proposed (Coimbra et al. 2002,2005 Boulet et al. 2007). 

In a similar approach, treatment of methyl glycosides with camphorsulfonic acid (CSA) in toluene under Dean-Stark conditions provides a good route to functionalized 1,6-anhydro sugars. Heathcock and co-workers showed that oxidation of the difficult-to-separate mixture of the l,6-anhydro- 8-D-glucopyranose (6) and l,6-anhydro- 8-D-glucofuranose (7) allowed for easy isolation of the desired ketone (8), by either chromatography or direct crystallization, depending on the reaction scale (O Scheme 4) [21]. 

G. O. Aspinall, Gas-liquid partition chromatography of methylated and partially methylated methyl glycosides, /. Chem. Soc., (1963) 1676-1680. 

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