Of methyl a-D-fructofuranoside

Platinum-catalyzed oxidation of methyl a-D-fructofuranoside (43) with oxygen is selective for C-6, and fructuronic acid (44) was obtained in 80% yield.151... 

Catalytic oxidation of methyl a-D-fructofuranoside over Pt C led to the uronic acid 96, which is the methyl-a glycoside of D-/yxo-5-hexulosonic acid.155... 

R. Cortes-Garcia, L. Hough, and A. C. Richardson, Acetalation of sucrose with concomitant fission of the glycosidic bond. Some new acetals of D-glucose and methyl a-D-fructofuranoside, J. Chem. Soc., Perkin Trans. 1 (1981) 3176-3181. 

As a taste stimulus, the effectiveness of sucrose over other disaccharides and the effectiveness of methyl B-D-fructofuranoside and methyl ct-g-gluco-pyranoside over other monosaccharides can be explained by the presence of one or more of the following types of sites sucrose, ct-D-glucopyranose and B-D-fructo-furanose. -... 

The observation of Purves and Hudson9192 that the /3-D-fructofurano-sidase enzyme of purified invertase hydrolyzes both sucrose and methyl /8-D-fructofuranoside but does not attack methyl a-D-fructofuranoside is decisive evidence that sucrose is a /3-D-fructofuranoside.4... 

Two crystalline benzyl fructosides have been prepared by Purves and Hudson. By treating crystalline methyl a-D-fructofuranoside with benzyl alcoholic hydrogen chloride they obtained a mixture which was partially hydrolyzed by invertase. Acetylation of the unhydrolyzed part gave a crystalline tetraacetate which was deacetylated to crystalline... 

The same reaction at 0° (18 hours) or at 64° (1 hour) gave a low yield (about 20 %) of the same dimethyl acetal, accompanied by a sirup which was shown to contain crystalline methyl a-D-fructofuranoside and the sirupy methyl 0-D-fructofuranoside hydrolyzed by invertase (see page 65). 

Considering that the acid-catalysed hydrolysis ( inversion ) of sucrose has been studied perfunctorily for the last century and a half, surprisingly little is known about the hydrolysis of ketosides. The positive entropies of activation of methyl /8-D-fructofuranoside (-t-13 eu) and sucrose (-1-8 eu) argue in favour of an A-1 mechanism [1] involving a fructofuranosyl cation. 

The H- and C-n.m.r. spectra of sucrose, methyl a-D-fructofuranoside (20) and methyl P D-fhictofuranoside (21) with single sites of C-substitution at C-1, C-2, C-3-, or C-6 of the furanose moieties have been analysed to assess the conformations of the their furanose rings, and of the glycosidic linkages in aqueous solution. In addition, spin-couplings in 20 and 21 were compared with those of a-(22) and p-D-r/jrco-pentulofuranose (23), respectively, to study the effect of glycosidation and hydroxymethyl substitution on the solution conformations. The conformations of 2-mono- and 2,2 -di-G-substituted a,a-trehalose derivatives 25 have been shown by n.m.r. spectroscopy in combination with molecular mechanics calculations, to differ from that of the 2,2 -unsubstituted disaccharide 24, both in solution and in the solid state. N.O.e. experiments on the 6 -deoxy-, 6 -thio-, and 6 -0-THP derivatives of methyl 2-acetamido-2-deoxy-P-lactoside, potential inhibitors of (2- 6)-a-sialyltransferase, proved that they adopt the same conformation as the parent compound. ... 

CII) exist. Furanosides, particularly of aldoses, are much more labile to acid than are the corresponding pyranosides dilute mineral acid (o.oi N) in the cold will hydrol) furanosides at an appreciable speed. In contrast o.i IV-acid at 100° for 4 h is normally required completely to recover the freesi iarfrom the aldopyranoside. In contrast, methyl a-D-fructofuranoside is hydrol5 sed only about three times as fast as the pyranoside. Pentop n ano-... 

However, some carbohydrates with a terminal D-fructofuranose residue are not suitable substrates for levan formation, e. g., methyl /3-d-fructofuranoside and inulin,64 even in the presence of enzymes98 which hydrolyze these substrates. 

The same holds for substitution at C3 and C5 of the fructofuranose moiety of sucrose neither melezitose (XV)61 nor o-D-glucopyranosyl-/3-D-xyloketofuranoside (XVIc)22 is hydrolyzed by yeast saccharase. As might have been expected from the experience with glycosidases, any change in the configuration of the fructon of sucrose results in stereoisomers unhydrolyzable by /3-fructofuranosidase. Thus, methyl and benzyl a-D-fructofuranosides,62 isosucrose (= /3-D-glucopyranosyl-a-D-fructo-... 

Although dilute aqueous acid hydrolyzed the methyl and benzyl a-D-fructofuranosides approximately 8 and 16 times as rapidly as sucrose, their method of preparation showed them to be unaffected by any of the enzymes active in a fermenting yeast suspension. Purified yeast invertase, proven free of a-D-glucosidases (maltases), could therefore contain no enzyme capable of hydrolyzing the above two a-D-fructo-furanosides, but did contain constituents that readily cleaved the beta isomers and also sucrose. The latter is accordingly a /S-D-fructofuranos-ide. When the evidence is put in this way, the present uncertainties as to whether purified invertase preparations include one or a number of /3-D-fructofuranosidases, and whether or not sucrose, methyl and... 

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