Desoxy-sugars

A novel approach to the synthesis of desoxy sugars was made by Jeanloz, Prins and Reichstein69 in 1945. In general terms, a 1,2-epoxide was cleaved with sodium thiomethoxide to give a /3-hydroxy thioether which, in turn, was hydrogenolyzed with Raney nickel. It is apparent... 

In an attempt to synthesize 2-desoxy-L-ribose, Mukherjee and Todd68 treated methyl 2,3-anhydro-jS-L-ribopyranoside (LXXII) with sodium thiomethoxide and then reduced the amorphous product. The sulfur-free sirup thus obtained was inert to the action of periodate and is therefore methyl 3-desoxy-/3-L-riboside (ayn., methyl 3-desoxy-/3-L-xyloside) (LXXIV) rather than the desired 2-desoxy derivative. The methylthio intermediate (LXXIII) was consequently a 3-methylthio-L-xylose derivative rather than a 2-methylthio-L-arabinose compound. The presence of a trace of the latter, however, is not wholly excluded since the sirupy desoxypentoside (LXXIV) gave a feeble green coloration in the Keller-Kiliani test, a reaction generally accepted as being specific for 2-desoxy-sugars. 

Oleficin (74), a polyenoyltetramic acid characterised by the presence of the desoxy sugar D-digitoxose on the C-3 hexenoyl side chain, is an antibiotic isolated from a strain related to Streptomyces parvulus [130]. 

Along the same line, on the other hand, methyl 2,3-anhydro -L-riboflido gives rise to a mixture of methyl 3-deeoxy-/S-L-xyloside and methyl 2-desoxy-0-n-arabinoside (Eq. 371), of which the 3-desoxy sugar is the principal constituent.1248 Analogous results were obtained separately in the d-series by other investigator 1 2 using lithium aluminum hydride. 

HDF has been identified as reaction product of a thermal treatment of sugars, especially the 6-desoxy sugar rhamnose [90], Analysis of the free sugars in the LMW-fraction revealed fructose-1,6-biphosphate (FBP) as the predominating carbohydrate in the LMW fraction (5.75 g/kg yeast), but no rhamnose was present [88]. To elucidate the contribution of FBP as precursors of HDF in the yeast fraction, the sugar phosphate was thermally degraded under the same conditions as used for the LMW fraction of yeast. The results revealed FBP, as effective precursor of HDF in aqueous model systems at lower reaction temperatures (100°C Table 19). It should be stressed that additions of the amino acids proline or alanine did not increase the concentrations of HDF from the carbohydrates listed in Table 19 (unpublished results). The data implied that FBP which was the predominant carbohydrate in yeast, is the... 

A number of methods available for the synthesis of 2- and 3-desoxy-sugars depend upon the cleavage by various reagents of a 2,3-anhydro ring in alkyl aldosides. An anhydro ring of this type can theoretically cleave in two ways, giving rise to two different products, e. g.,... 

Using the various methods described for the preparation of 2-desoxy-sugars, Reichstein and his colleagues have synthesized the 2-desoxyhexo-methyloses and 3-methyl-2-desoxyhexomethyloses which occur naturally as carbohydrate components of the cardiac glycosides. The present account refers briefly only to those researches reported since 1945 (see ref. 1). 

Overend, W. G., and Stacey, M., The Chemistry of the 2-Desoxy-sugars, VIII, 45-105... 

With Dische s reagent for 2-desoxy sugars (diphenylamine in acetic acid and sulfuric acid) triacetyl-D-glucal and a series of other glycals and glycal derivatives give the same or a similar color as the 2-desoxy sugars.25-28... 

Desoxy Sugars.—The addition of water to the double bond of a glycal leads to a 2-desoxyaldose. 

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