Fructofuranosides isolation

The synthesis of (3-D-fructofuranosides is yet another useful application of this concept [293-295]. The latter 1,2-cis-glycosidic linkage is as difficult to establish as in the case of (3-mannosides. In an elegant synthesis of a-D-fucofuranose-containing disaccharides, Plusquellec and coworkers used the IAD concept via p-methoxybenzylidene acetals in combination with a glycosylation protocol via pentenyl glycosides. Here, the intermediate NIS-adduct could be isolated (Scheme 5.108) [295]. 

Glycosylating Claviceps strains (mostly C. fusiformis) produce most elymoclavine in the form of p-fructofuranosides, which complicates the isolation of elymoclavine. The hydrolysis of fructosides by HCl is not suitable for a large scale process due to the aggressive nature of the acid solution and losses of elymoclavine. A more elegant method is a bioconversion employing the high invertase activity... 

The separation of glycosides on a cellulose column was first applied to a mixture of pyranosides28 subsequently, separations were achieved for the methyl D-fructofuranosides and D-galactofuranosides.28 This technique was soon applied to many other mixtures it permits not only the isolation of crystalline products, but also a more quantitative evaluation of the formation of glycofuranosides.80-34... 

Morgenlie95 isolated a tetrasaccharide from Festuca rubra, and elucidated its structure as being 0-a-D-galactopyranosyl-(l- 4)-0-a-D-ga-lactopyranosyl-(l- 3)-a-D-glucopyranosyl /3-D-fructofuranoside. Raf-finose and stachyose co-exist with this tetrasaccharide. 

When the Claviceps strain SD 58 was grown in a culture medium containing saccharose the slow formation of alkaloids containing polar groups was observed (15). These could not be extracted from the water phase in either alkaline or acid medium by the usual solvents. Finally, the principal alkaloid was isolated by ion exchange procedures and purified by subsequent chromatographic methods. The alkaloid was identified as elymoclavine-O-jS-D-fructofuranoside (12 ... 

For ethyl D-fructofuranoside, both anomers are formed in small proportion during the hydrogenolysis of sucrose in ethanol. When the reaction was performed at 100° in an atmosphere of argon, considerable quantities were obtained. Ethyl S-D-fructofuranoside, [ ]d —36° (in water), is readily hydrolyzed to D-fructose by invertase (and also by 0.1 N sulfuric acid) at room temperature. The same behavior was observed for a substance isolated from wheat germ. Acetylation yielded a sirupy product, but treatment with trityl chloride gave crystalline methyl 1,6-di-O-trityl-D-fructoside (m.p. 180-183°). With p-toluenesulfonyl chloride, a crystalline product is obtained, with m.p. 125-127°. Ethyl a-D-fructofuranoside ([ ]d +65°, in water) is not attacked by invertase. Tritylation, followed by acetylation, gives ethyl 3,4-di-O-acetyl-l, 6-di-O-trityl-ai-D-fructofuran-oside m.p., 142-144° and [q ]d +44.5° (in chloroform). 

Kestose or 0-a j>-GlucopyranosyU l- 2) 0 P-jy-fructofuranosyl- 6- 2) p i>-fructofuranoside. This sugar is produced during the action of yeast invertase on a 50 % sucrose solution and can be isolated by cellulose chromatography The trisaccharide crystallizes from methanol and (with some dif-... 

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