Other Dideoxy Sugars

4-dideoxy sugars have not been found in Nature. Some of them have been synthesized for structure-activity relationships. 2,  

3 -Dideoxynucleosides are of interest because several members of this group exhibit potent antiviral activity against HIV, for example 169 and 170.246 

Enantioselective synthesis of 2,3-dideoxy-D-erythro and D-z7zreo-hexoses has been achieved, in several steps, starting from furfural.247 

Methyl 2,4-dideoxy-p-L-eryt/zro-hexopyranoside has been obtained as intermediate in the synthesis of 8-hydroxy-p-lysine, from D-galacturonic acid.249 

The syntheses of the thymine nucleosides of 2,4-dideoxy-p-D-eryt/zro-hexo-pyranose starting from l,2 5,6-di-(9-isopropylidene-a-D-glucofuranose (12 steps) or from tri-O-acetyl-D-glucal (11 steps) have been reported.250 

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The paper-chromatographic properties of the common deoxy and dideoxy sugars have been treated in several reviews,2 28 a book,829 and individual publications. Common solvent-systems are 6 4 3 1-butanol-pyridine-water (Solvent A) 4 1 5 1-butanol-acetic acid-water (Solvent B) and 1-buta-nol-ethanol-water (4 1 5, upper phase, Solvent C or 3 1 1, Solvent D). The four 2-deoxy-D-hexoses and the 2,6-dideoxyhexoses may be separated as their borate complexes. 0 The use of 1-butanol-water on the one hand, and of 2-butanone-borate buffer on the other, usually provides adequate separation and, by use of a combination of solvents, these deoxy sugars may be identified. 80 The use of buffered systems has proved highly advantageous in the separation and identification of the isomeric 6-deoxy-hexoses.8 1 Other systems, such as Solvent A and 2 1 2 ethyl acetate-... 

Andreana et al. [25] have recently invoked RCM to prepare /J,y-unsaturated <5-lactones (Scheme 3). Exposure of dienes of general type 13 to either 2 or 4 (which could be used at lower loadings) readily furnished lactones 14. For other examples of a,/ -unsaturated <5- and y-lactone synthesis by RCM see Ref. [26]. Variation of the configuration at the chiral carbons and the ligand for the asymmetric dihydroxylation reaction allows access to an array of biologically important dideoxy-sugar derivatives. 

Variants of keratan sulfate in which other neutral sugars occur and in which there is more than 1 mole of sulfate ester per disaccharide repeating unit are known. Keratan sulfate has also been found to contain smaller amounts of neutral monosaccharides, such as D-mannose and L-fucose, and 5-amino-3,5-dideoxy-D-gZj/cero-D-gcZacto-2-nonulosonic acid. 

Azido-2-deoxy- and 2,4-diazido-2,4-dideoxy-D-glucose have been synthesized from derivatives of l,6 2,3-dianhydro-j8-D-mannopyranose as indicated in Scheme 57 339 Other azido-sugars and a 5 -azido-5 -deoxynucleoside are mentioned in Chapters 8 and 21, respectively. 

The syntheses of L-cladinose (7) and its C-3 epimer (8) have been achieved by the desulfurization of 2,6-anhydro-2-thiopyranoside derivatives (Scheme 2). A full paper on this work together with other related 2,6-dideoxy sugars has also appeared. ... 

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