Sorbose from fructose

When D-fructose and L-sorbose are refluxed with aqueous HC1, dihexulose dianhydrides are formed.91 If the water is replaced by N./V-dimethylformamide, substantially increased yields are obtained and 1,2-linked disaccharides are detected. Higher yields of dianhydrides were obtained from fructose, rather than sorbose, under comparable conditions. Treatment of levan with dilute H2S04 at 60°C yielded92 a-D-Fru/-l,2 2,1 -fi-D-Fru/(5). Presumably, any products that contain 2,6-linkages with large central rings would rapidly isomerize to the more stable 1,2-linked product. 

Some compounds having two carbon substituents at the anomeric centre have been reported. Thus glycosyl cyanides prepared from sorbose and fructose have been described and have led, for... 

On the other hand, the product from glucose is an exceedingly complex mixture, the composition of which varies with the conditions of treatment. D-Psicose (from treatment with ammonia) (55) and (dl + n)-sorbose (from treatment with a strong base resin) 90) have been identified definitely in the mixture. D-Glucose is readily converted to D-fructose. From the latter has been isolated after treatment with potassium hydroxide (dl + D)-sor-... 

D-Ketohexose-3-epimerase, a new enzyme isolated from Pseudomonas sp., catalysed the epimerization between D-tagatose and D-sorbose, D-fructose and D-psicose, D-xylulose and D-ribulose, and between L-xylulose and L-ribulose. ... 

A short route from fructose to deoxymannojirimycin is illustrated in Scheme 2. The same group have also prepared 1-deoxygaIactonojirimycin from sorbose. ... 

The main drawback of the system is that the ketone catalyst slowly decomposes during the reaction, which means that 0.2-0.3 equivalents are needed for complete conversion. More robust catalysts, which can be used in 1-3 mol%, have recently been reported, but have not as yet been widely applied [8]. Ketone 1 is commercially available, or can easily be synthesized in large scale in two steps from d-fructose. Ent-1 is obtained in a similar way from L-sorbose. 

In 1952, Wolfrom and Hilton demonstrated that L-sorbose was also capable of forming dimeric dianhydrides,22 and they postulated sorbofuranosyl and pyra-nosyl cationic intermediates. In 1955, Boggs and Smith23 postulated a fructofu-ranosyl cationic intermediate in the formation of per-O-acetyl ot-D-Fru/-1,2 2,l -p-D-Fru/[di-D-fructose anhydride I (5)] from inulin triacetate. They indicated that three adjacent P-2,l -linked fructofuranosyl units would be required for formation of the dianhydride. 

Some examples will illustrate the applicability of this generalization in so far as it concerns alkaline scission. 5,6-Anhydro-l,2-isopropylidene-D-glucofuranose with alcoholic sodium hydroxide gives a mixture of isopropylidene-D-glucose and isopropylidene-L-idose. The latter results from inversion on C5, the former presumably by inversion on the non-asymmetric C6.7 3,4-Anhydro-l,2-isopropylidene-D-psicose (or allu-lose17) (XX) when treated with sodium hydroxide yields a mixture of products among which 1,2-isopropylidene-D-fructose (XIX) was detected (in the representations inversions are denoted by circles above the arrows and the carbons inverted are noted below the arrows). With sodium methoxide, however, l,2-isopropylidene-4-methyl-D-sorbose (XXI) is the chief product and results from inversion on C4.1S... 

The ketone catalyst is readily prepared from D-fructose by ketalization and oxidation. The other enantiomer of this ketone, prepared from L-sorbose,... 

From a structural point of view, the carbohydrate template can have either furan or pyran rings although in some cases open chain structures can be formed. A large variety of aldopentoses (e.g. d- and L-arabinose, D-ribose, D-xylose), aldohexoses (e.g. D-glucose, D-mannose, D-galactose) as well as ketohexoses (e.g. D-fructose, L-sorbose) can be used as scaffolds. 

In the continuation of this work, a broad range of OZTs was prepared from selectively protected derivatives of D-fructose and L-sorbose (Scheme 26).47... 

The direct syntheses of D-glucosyl-L-sorboside from sucrose and L-sorbose and of sucrose from D-glucosyl-D-xyloketoside and D-fructose can be obtained in phosphate-free enzyme preparations.40 The reactions are ... 

A prior report proposed that 3-deoxyhexosuloses participate in the formation of 11 (see Scheme 7). The 3-deoxyhexosuloses were isolated from heated, acid reaction mixtures involving D-fructose and L-sorbose. It was suggested that 3-deoxyhexos-2-ulose (39) underwent reversible equilibrium with 38, its cis form, and was further dehydrated at C-3 and C-4, to form 3,4-dideoxyhex-3-enos-2-ulose (40). This intermediate cy-clized to the furaldehyde. Experiments involving treatment of both... 

In 1996, ketone 26 was reported to be a highly effective epoxidation catalyst for a variety of trans- and trisubstituted olefins [53]. Ketone 26 can be readily synthesized from D-fructose by ketalization and oxidation (Scheme 2) [54-56]. The enantiomer of ketone 26 (ent-26) can be obtained by the same methods from L-fructose, which can be obtained from L-sorbose [57, 58]. 

Sorbitol can be made by the reduction of three naturally occurring hexoses, D-glucose, D-fructose and L-sorbose. D-Mannitol and L-iditol, respectively, are concurrently produced from the ketoses. However, D-glucose, because of its greater availability, is the only practical source. 

Isbell and co-workers (51) have tried to minimize the oxygen reaction and to maximize the peroxide reaction. When a large excess of peroxide and a low temperature were maintained, they found that the monosaccharides are converted almost quantitatively to formic and two-carbon acids. Table II presents results for the peroxide oxidation of 14 sugars. The total acid produced from aldo-hexoses under favorable conditions is about six moles, consisting almost entirely of formic acid. Aldopentoses react more rapidly than aldo-hexoses and yield about five moles of formic acid per mole of pentose. Fructose and sorbose yield approximately five moles of total acid of which four moles are formic acid. Glycolic acid was identified qualitatively but not determined quantitatively. L-Rham-nose and L-fucose yield about five moles of acid, including four moles of formic acid. Acetic acid was identified only qualitatively. 

Scheme 7.—The Equimolar Mixture of D-Fructose and L-Sorbose Obtained from dl-2,3-Dihydroxypropanal in the Reaction Catalyzed by the Glycolysis Aldolase.

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