2-Deoxysugars

Generally speaking, the phosphorylated deoxysugars undergo the usual reactions of carbohydrates without complication. For instance, both 2-deoxy D-ribose 5-phosphate (52, 59) and 2-deoxy D-xylose 5-phosphate (2) can be reduced to the corresponding 2-deoxy d-erythro- (48) and 2-deoxy D-threo-pentitol 5-phosphates (49). 2-deoxy ribose 5-phosphate has also been oxidized (52) to the corresponding phosphorylated acid (50). 

Using (31) as the nucleophile, FSA has been shown to accept several aldehydes as acceptor components for preparative synthesis [91]. In addition to (31), it also utilizes hydroxyacetone as an alternative donor to generate 1-deoxysugars such as (66) regioselectively (Figure 10.25). 

Figure 10.16 Natural substrates of microbial deoxysugar phosphate aldolases.

Figure 10.25 Inverted approach for aldose synthesis using FruA catalysis, and application ofthe strategy for deoxysugar synthesis based on a phosphorothioate analog synthesis of 1-deoxysugars by FSA catalyzed addition of hydroxyacetone.

Schurmann, M., Schurmann, M. and Sprenger, G.A. (2002) Fructose 6-phosphate aldolase and 1-deoxy-D-xy lulose 5-phosphate synthase from Escherichia coli as tools in enzymatic synthesis of 1-deoxysugars. Journal of Molecular Catalysis B, Enzymatic, 19, 247-252. 

Special topics (synthesis of P-mannosides, furanosides, sialosides, glycosides of aminosugars and deoxysugars, if applicable)... 

Transformation of 2-deoxysugar derivatives into glycosyl xanthates can be performed by the treatment of O-benzyl-protected hemiacetal derivative with diphe-nylphosphoryl chloride, followed by the reaction with O-ethyl potassium xanthate in the presence of a base (NaOH, PTC reaction or NaH in appropriate organic solvent). High yields and selectivities in such reactions were observed when using sodium hydride in anhydrous THF [401],... 

For the synthesis of glycans containing 2-amino-2-deoxysugars, the regioselective azidophenylselenation of glycals is popular [524—528]. This methodology follows on from the classic azidonitration work of Lemieux and Ratdiffe, first reported in the... 

Fused cyclic ethers can be derived from appropriately substituted sugars. An example is given with the stereoselective 5-exo radical cyclization of allylic 2-bromo-2-deoxysugars, in the presence of 1,1,2,2-tetraphenyldisilane as the radical mediator and AIBN in refluxing ethyl acetate. The corresponding cis-fused bicyclic sugars have been prepared in moderate to good yields (Reaction 7.28) [39]. 

Glycosyl fluoride Fluoro-deoxysugar Fluorosugar Fluoro-C-glycosIde... 

Our original paper on DXS has up to now been quoted in more than 200 articles. Purified DXS can be used further for the chemoenzymatic syntheses of various 1-deoxysugars and 1-deoxysugar phosphates, as shown by our group and others [22]. 

FSA makes it possible to use dihydroxyacetone or hydroxyacetone as a donor compound for aldolization reactions this opens up the field for novel carbohydrate compounds such as 1-deoxysugars which otherwise can be obtained by DXS through a different reaction. 

Asymmetric synthesis of 1-deoxysugars and sugar phosphates using DXS and/or FSA enzymes a) Me. Schtirmann, Ma. Schtirmann, G. A. Sprenger,/. Mol. 

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