Deoxy sugars, natural occurrence

Deoxyketoses are of rare natural occurrence. The antibiotic hygromycin177 has been shown to contain 6-deoxy-D-arabmo-hexos-a-ulose residues, since reduction of the free sugar gave 6-deoxy-D-altrose and L-fucose. Yungsten and coworkers171 reported the isolation of a 6-deoxy-L-x2/io-hexulose (an-gustose) from the antibiotic Angustmycin A, for which structure (37) was proposed. 

Deoxy sugars are of wide occurrence as components of nucleic acids, natural glycosides, and antibiotics, and they were the subject of an earlier article by Hanessian in Volume 21. Here, de Lederkremer and Marino (Buenos Aires) provide a detailed update on the distribution of deoxy sugars in natural products, along with a survey of methods for their synthesis. 

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. 

R. Schaffer, Occurrence, properties and preparation of naturally occurring monosaccharides (including 6-deoxy sugars), in W. Pigman and D. Horton (Eds.), The Carbohydrates Chemistry and Biochemistry, 2nd edn., Vol. IA, Academic Press, New York, 1972, pp. 69-111. 

Occurrence. D-Ribose (9) and 2-deoxy-D-eryf/iro-pentose ( 2-deoxy-D-ribose ) are the carbohydrate constituents of nucleic acids, which are found in all cells. D-Ribose is also a constituent of several coenzymes. In these natural products, the sugar occurs in the (3-furanose form. 

Occurrence and preparation. 6-Deoxy-L-altrose (34) is a monosaccharide occurring rarely in Nature. 6-Deoxy-L-altropyranose forms homopolysaccharide O-chains in LPSs of some Yersinia enterocolitica serovars.164 6-Deoxy-L-altrofuranose is one of the constituent monosaccharides of an O-specific polysaccharide of Y. pseudotuberculosis serovar VB165 and was also found in a polysaccharide from Campylobacter jejuni 176.83 (serotype 0 41) that contains only furanose sugars.30 A homopolymer of 6-deoxy-L-altrofuranose has been found in the LPS of Pectinatus frisingensis,166 which is in turn the source for the isolation of this sugar. 

In recent years branched-chain sugars of comparatively rare occurrence have been isolated from natural sources as examples, apiose from the parsley plant and the leaves and fibres of Posidonia australis (p. 59), hamamelose from the tannin of witch hazel bark, and deoxy branched... 

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