Carbohydrate derivatives, nitrile oxide cycloadditions

A comprehensive review (260 refs.) on the synthesis of carbohydrates from noncarbohydrate sources covers the use of benzene-derived diols and products of Sharpless asymmetric oxidation as starting materials, Dodoni s thiazole and Vogel s naked sugar approaches, as well as the application of enzyme-catalysed aldol condensations. The preparation of monosaccharides by enzyme-catalysed aldol condensations is also discussed in a review on recent advances in the chemoenzymic synthesis of carbohydrates and carbohydrate mimetics, in parts of reviews on the formation of carbon-carbon bonds by enzymic asymmetric synthesis and on carbohydrate-mediated biochemical recognition processes as potential targets for drug development, as well as in connection with the introduction of three Aldol Reaction Kits that provide dihydroxyacetone phosphate-dependent aldolases (27 refs.). A further review deals with the synthesis of carbohydrates by application of the nitrile oxide 1,3-dipolar cycloaddition (13 refs.). ... 

Further attempts to increase the kinetics and biocompatibility of 1,3-dipolar cycloadditions led organic chemists to explore altemative dipoles that react with multiple-bond reaction partners. Nitrile oxides are highly reactive dipoles that can react with various alkenes and alkynes to provide isoxazolines and isoxazoles, respectively. In the absence of a suitable reacting partner, nitrile oxides tend to dimerize to form fiiroxane derivatives, or can alternatively act as electrophiles. However, when generated in situ from suitable precursors such as hydroximoyl chlorides or by mild oxidation directly from oximes, nitrile oxides were successfully applied to the labeling of nucleic acids [43], peptides [44] and carbohydrates [45] (Fig. 7). 

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