Sugar natural/unnatural sugars

Combined Use of Aldolases and Isomerases for the Synthesis of Natural and Unnatural Sugars... 

The allylation and crotylation of a-alkoxy aldehydes provide chiral 1,2-diol synthons which can be used in the synthesis of polyoj genated small molecules, for example, natural and unnatural sugars The tartrate-derived allylboronates I and 2 provide reagent-controlled selectivity in reaction with chiral glyceraldehyde acetonide 30. The intrinsic selectivity of the aldehyde is estimated by its reactions with pinacol allylboronates 33 and 34. The reagents 1 and 2 overcome the aldehyde s... 

Assay results with the two new 1,2-cis (ft-d) cardenolides show enhanced activity as compared with the two unnatural, a-D-rhamnosides. They have potencies that fall well within the range for those of the naturally occurring cardenolides. These results support the postulate that the a-D-glycosidic linkage in cardenolides containing D-sugars is unfavorable for cardiotonic activity. 

Grouped in this Section are the C-D-pentofuranosyl-imidazoles, -pyrazolopyrimidines, and -adenines. The last two analogs are positional isomers of formycin in which the heterocyclic moiety is attached to the sugar at an unnatural position. A rationale103 for the synthesis of this type of analog is of interest it was based on the possibility of a close structural similarity between a natural adenine nucleoside and synthetic analog with respect to available hydrogenbonding sites. 

Jiang J, Biggins JB, Thorson JS (2000) A general enzymatic method for the synthesis of natural and unnatural UDP- and TDP-nucleotide sugars. J Am Chem Soc 122 6803-6804... 

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