Sugar derivatives, deoxygenation

However, it is rather difficult to search a library of natural sugars for an appropriate sugar derivative for the synthesis of 30. It is necessary to find either 5-deoxy-L-arabinose (61) or 5-deoxy-L-ribose (62), neither of which is available from natural resources [69]. Chemical derivation from easily available sugars is the only way to obtain 61 and 62,however, simple deoxygenation of the terminal alcohol group from L-arabinose (63) and L-ribose (64) generally requires a multi-step process. For example, the deoxygenative transformation... 

The saccharides represent a structurally diverse group of compounds, which are often derivatised with a variety of functional groups. The chemical modification of saccharides often involves the installation of a functional group that at an appropriate time can be converted into another functionality. In this chapter, synthetic methodologies for the preparation of halogenated, unsaturated and deoxygenated sugar derivatives will be discussed and furthermore methods for the introduction of amino, sulfate and phosphate moieties will be covered. 

The same polymer-supported organotin reagent was also used in the Barton-type deoxygenation of steroid derivatives, sugar derivatives and diols160. Furthermore, the radical deamination of secondary and tertiary amines via the corresponding isocyanides was also reported160,169. 

Scheme 22.22 Site-selective thiocarbonylation/deoxygenation of sugar derivatives.

Several deoxy sugars have trivial names established by long usage, e.g. fucose (Fuc), quinovose (Qui) and rhamnose (Rha). They are illustrated here in the pyranose form. These names are retained for the unmodified sugars, but systematic names are usually preferred for the formation of names of derivatives, especially where deoxygenation is at a chiral centre of the parent sugar. (See also the alphabetical listing of trivial names in the Appendix.)... 

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