6-Deoxy-D-galactose

Alkyl (or acyl) derivatives of the 6-amino-6-deoxy carbohydrates are examples of derivatives in which the hydrophilic and hydrophobic moieties are linked at other positions than C-1. Thus 6-amino-6-deoxy-D-galactose derivatives 34 were prepared from l,2 3,4-di-0-isopropylidene-6-0-tosyl-a-D-galacto-pyranose by the following reactions (1) substitution of the leaving group at C-6 by a phthaloyl function, (2) hydrazinolysis to afford a 6-amino-6-deoxy intermediate, (3) reaction of acyl or sulfonyl chlorides at the amino function, (4) deprotection of the acetal rings to afford the expected glycolipid 34 [56]. 

Reduction of dTDP-6-deoxy-D-xy/o-hexos-4-ulose (7a) at C-4 of the hexosyl group should lead to dTDP derivatives of 6-deoxy-D-glucose (d-quinovose) and 6-deoxy-D-galactose (D-fucose). Although D-quinovose and D-fucopyranose have not been found as components of bacterial polysaccharides, the corresponding glycosyl nucleotides were identified147 in extracts of Escherichia coli Y-10. 

The isolation of D-fucose (6-deoxy-D-galactose) instead of galactose as a major product of the catalytic oxidation-reduction was considered to be the consequence of / -elimination of the initially formed 4-ulose-derivative. The removal of water resulted in the formation of a 4-keto-5,6-glucoseen which upon catalytic reduction yielded 6-deoxy-D-glactose. Thus, it seems that it is the intrinsic property of methyl-D-xylo-4-hexu-loside to undergo molecular rearrangement spontaneously. 

From these results with 5-acetamido-5-deoxyhexoses and 6-acet-amido-6-deoxyhexuloses, it seems plausible that 6-acetamido-6-deoxyaldoses cannot form nitrogen-containing septanoid rings for example, 6-acetamido-6-deoxy-D-galactose and 7-acetamido-7-deoxy-L-gflZflcto-heptulose exist only in the pyranose forms. 

The series D-galactose, 6-deoxy-D-galactose, 6-deoxy-6-fluoro-D-gaIactose,... 

The synthesis of oct-2-ulosono-1,4-lactone phenylhydrazones from D-gluconic acid is covered in Chapter 16, while the formation of a 1-C-substituted 1,5-dideoxy-l,5-iminopentitol by reduction of 6-azido-6-deoxy-D-galactose diphenyl-formazan with triphenylphosphine is detailed in Chapter 18. 

Reduction of 6-azido-6-deoxy-D-galactose JV,iV -diphenylformazan with triphe-nylphosphine afforded the 1,5-imino-D-lyxitol compound 44S ... 

Asterosaponin A a steroid saponin (see Sapo-nins). The aglycon is 3p,6a-dihydroxypregn-9(ll)-en-20-one, which contains a pregnane ring system (see Steroids), and which is linked to 2 molecules each of 6-deoxy-D-glucose and 6-deoxy-D-galactose, and one... 

O -a-D-Galactopyranosy 1-6-deoxy-D-galactose, G-74 2-0-p-D-Galactopyranosyl-6-deoxy-L-galactose, G-75 4- O - p-D-Galactopyranosyl-6-deoxy-L-galactose, G-76... 

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