Monosaccharides deoxy sugars

Deoxy sugars, as we saw in Section 25.7, have an oxygen atom "missing." That is, an —OH group is replaced by an -H. The most common deoxy sugar is 2-deoxyribose, a monosaccharide found in DNA (deoxyribonucleic acid). Note that 2-deoxyribose exists in water solution as a complex equilibrium mixture of both furanose and pyranose forms. 

The generic term monosaccharide (as opposed to oligosaccharide or polysaccharide) denotes a single unit, without glycosidic connection to other such units. It includes aldoses, dialdoses, aldoketoses, ketoses and diketoses, as well as deoxy sugars and amino sugars, and their derivatives, provided that the parent compound has a (potential) carbonyl gTOup. 

Monosaccharides in which an alcoholic hydroxy group has been replaced by a hydrogen atom are called deoxy sugars (see 2-Carb-13). 

Note. A monosaccharide with a terminal methyl group is named as a deoxy sugar, not as a C-methyl derivative. 

Tables V-LVII detail H and F shift and coupling information, and Tables LVIII to LXXI incorporate the C-n.m.r. data. The data within this compilation are arranged according to the following outline hexoses prior to pentoses, followed by anhydro sugars, sugar acids and lactones, amino sugars (and their synthetic, A -containing precursors), mono-, di-, and tri-deoxy sugars, branched derivatives, ketoses, polyfluorinated monosaccharides, and, finally, difluorinated amino sugars. Within this compilation, and even within each table, pyranoid derivatives are listed prior to their furanoid counterparts, hexoses prior to pentoses, functionalized prior to deoxy compounds the arrangement within each sub-table is made alphabetically.

Dimethylthiocarbamates are known to undergo photochemical cleavage, leading, in the case of monosaccharide derivatives, to deoxy sugars and to free alcohols (see Scheme 12). ... 

If any monosaccharide lacks the usual numbers of hydroxyl groups, it is often caUed a deoxy sugar. For example, 2-deoxyribose, which is a component of DNA nucleosides, has one less hydroxyl group than its parent sugar, ribose. 

Hence, the size of ring of monosaccharides must be deduced from their mass spectra with caution, because of the possibility of rearrangements, especially in the case of derivatives of deoxy sugars. 

Horton, D., Tables of Properties of 2-Amino-2-deoxy Sugars and Their Derivatives, 16, 159-200 Horton, D., and Hutson, D. H., Developments in the Chemistry of Thio Sugars, 18, 123-199 Horton, D. See also, Foster, A. B. Hough, L., and Jones, J. K. N., The Biosynthesis of the Monosaccharides,... 

In an article that collates information not extensively treated before, Z. J. Witczak (West Lafayette) describes the synthesis, chemistry, and preparative applications of monosaccharide thiocyanates and isothiocyanates the thiocyanate anion is an ambident nucleophile of great synthetic versatility in approaches to nucleoside analogs and to thio and deoxy sugars. 

The iodo and bromo derivatives of monosaccharides can be reduced by a variety of reducing agents to afford the corresponding deoxy sugar. Many such examples have been presented. The more stable chloro derivatives can be reduced with Raney nickel (Scheme 1). Selective reduction of a secondary chloride with respect to a primary chloride may be achieved if the reduction is performed in the presence of triethylamine.11,12 Selective reduction of a secondary chloride has been also achieved by using organotin hydrides.13 The radical initiator... 

Monosaccharides with modified structures are often biologically important. Examples include sugar phosphates, deoxy sugars, amino sugars, and ascorbic acid (vitamin C). 

In O Scheme 1, O Scheme 2 and O Scheme 3, some of the important representatives of natural monosaccharides are presented and compiled by the three different classes deoxy-sugars, amino-sugars, and branched-chain sugars. O Table 1 lists their names and natural sources of occurrence. 

Deoxy-sugars are very common monosaccharides and are frequently found as components of oligosaccharides in antibiotics. A large number of the so-called bioactive lipopolysaccharides as well as several antibiotics are deoxy-sugars [41]. 

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