Fructo furanose

Disaccharides such as isomaltulose (6-a-D-glucopyranosyl-D-fructo-furanose), obtained in one step from sucrose by bioconversion (Scheme 12),44 Isomalt , the hydrogenated derivative of isomaltulose and trehalulose (1-a-D-glucopyranosyl-D-fructopyranose) have been shown to be interesting substrates for chemistry.45... 

Though there is no direct evidence that the D-fructofuranose unit in melezitose is of -configuration, the facts that all naturally occurring fructofuranoside sugars known so far are sucrose or sucrose derivatives and that the equilibrium mixture of D-fructose appears to consist almost entirely of /3-o-fructopyranose and /3-D-fructo-furanose, are very suggestive of a /3-configuration. For a full discussion of the problem see C. S. Hudson, Advances in Carbohydrate Chem., II, 1 (1946). 

The action of dry hydrogen chloride on D-fructose gave di-/9-D-fructo-furanose 1,2 2,1 -dianhydride as the product isolated.1 7... 

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. -... 

Q-fructose (Figure 4), which has 31% B-D-fructo-furanose (30), was also a highly stimulatory monosaccharide. 

Bell114 has suggested that the very ready hydrolysis of a -diisopro-pylidene-D-fructose might possibly indicate a furanose structure, namely, that a-diisopropylidene-D-fructose is l,2 4,6-diisopropylidene-D-fructo-furanose. Hydrolysis would have to be accompanied by change in the size of the ring since the structure of the mono-isopropylidene derivative is, without doubt, pyranose. In this connexion, however, it should be... 

Similar investigations were conducted on XXII. Its partial hydrolysis produced two products, l,l-C-diphenyl-2,3-isopropylidene-D-fructo-furanose (XXV), and l,l-C-diphenyl-2,3-isopropylidene-D-fructopyra-nose (XXVI). Both XXV and XXVI were non-reducing, establishing the involvement of the reducing carbon atom with an acetone residue. 

Inulin carbonate can be synthesized with ethyl chloroformate in dimethyl sulfoxide with triethy-lamine as the catalyst (Figure 5.5) (Kennedy and Tun, 1973). This yields a mixture of two products one with O-ethoxycarbonyl groups (5) and the second with trans-4,6-carbonate (6) on the fructo-furanose groups of the inulin chain and a trans-2,3-cyclic carbonate on the terminal glucose (7). Inulin carbonates have utility in the insolubilizaton of biologically active molecules such as enzymes or immunoglobulins. 

D-Fructose, a ketohexose, can potentially form either a five-membered (furanose) or a six-membered (pyranose) ring involving formation of an internal hemiketal linkage between C2 (the anomeric carbon atom) and the C5 or C(, hydroxyl group, respectively. The hemiketal linkage introduces a new asymmetrical center at the C2 position. Thus, two anomeric forms of each of the fructo-furanose and fructopyranose ring structures are possible (Figure 9-10). In aqueous solution at equilibrium, fructose is present predominantly in the )3-fructopyranose form. 

The resistance to iodide displacement of 1-O-sulfonyl derivatives of D-fructose and D-sorbose is well known,287 and selective displacement at C-6 of 2,3-0-isopropyIidene-l,6-di-0-p-tolylsulfonyl-D-fructo-furanose by sodium a-toluenethioxide in methanol gave 6-S-benzyl-2,3-0-isopropylidene-6-thio-l-0-p-tolylsulfonyl-D-fructofuranose in 74% yield.218... 

Zervas and Sessler synthesized an isomeric mono-O-isopropylidene-D-fructose by acetonating 1,6-di-O-benzoyl-D-fructose, prepared by treatment of D-fructose cyanohydrin with two molar proportions of benzoyl chloride in the presence of pyridine. The cyclic acetal obtained after debenzoylation was named 2,3-acetone-a-D-fructo-furanose by the authors, although, quite evidently, it is 2,3-0-isopropylidene-j8-D-fructofuranose (90). 

D(+)-Raffinose (5H2O) (Melitose, 6-O-a-D-galactopyranosyl-D-glucopyranosyl-P-D-fructo-furanose... 

Levan bacteria, extracellular anhydro-D-fructo-furanose in predominantly y6(2-6) linkage and some y6(l-2) linkage... 

The anomeric configurations in a-D-fructofuranose g-D-fructo-furanose 2, 1 2,3 -dlanhydrlde, a product formed in high yield by the action of a D-fructotransferase on Inulln, have been determined from its C-n.m.r. spectrum.A H-n.m.r. study on tosylated derivatives of 1,6-anhydro-g-D-glucopyranose is mentioned in Chapter 20. 

Immel S, Schmitt GE, Lichtenthaler FW (1998) Cyclofructins with six to ten -linked fructo-furanose units geometries, electrostatic profiles, lipophUicity patterns, and potential for inclusion complexation. Carbohydr Res 313 91-105... 

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