Deoxyhexonic acid

Fig. 7 -31. Peeling and stopping reactions of polysaccharides (Sjostrom, 1977). R = polysaccharide chain and R = CH2OH (cellulose and glucomannans) or H (xylan). Cellulose and glucomannans (R = CH2OH) (1) 3-Deoxyhexonic acid end groups (metasaccharinic acid), (2) 2-C-methylglyceric acid end groups, (3) 3-deoxy-2-C-hydroxymethylpentonic acid (glucoisosaccharinic acid), (4) 2-hydroxypropanoic acid (lactic acid), and (5) 3,4-dideoxypentonic acid (2,5-dihydroxypentanoic acid). Xylan (R = H) (3) 3-Deoxy-2-C-hydroxymethyltetronic acid (xyloisosaccharinic acid), (4) 2-hydroxypropanoic acid (lactic acid), and (5) 2-hydroxybutanoic acid. 1977. TAPPI. Reprinted from Tappi 60(9), p. 152, with permission.

Considered together, the above observations provided evidence for the presence of hydroxyl groups on C2, C4, C5, and C6 of a -D-galactometa-saccharinic acid, and, hence, for its formulation as a 3-deoxyhexonic acid. 

Several reactions involving jS-eliminations from 2-amino-2-deoxyhexonic acid derivatives have been reported. For example, 2-benzamido-4,6-0-benzylidene-2-deoxy-D-gluconic acid (87, R = H), on heating in pyridine... 

It was furthermore reported that reduction of the unsaturated deoxyhexopyranuronate degradation product (54) with sodium borohydride gives an epimeric mixture of the corresponding 3-deoxyhexonic acids (56 and 57). Ruff degradation of this mixture of compounds results in 2-deoxy-L- /ifeo-pentose (58). 

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