Heptulosaric acids

A 3-deoxyheptulosaric acid has been found in the LPS from Acineto-bacter calcoaceticus NCTC 10305. Another acid of this class, 3-deoxy-o-/yxo-heptulosaric acid ° (30), is a component of a plant polysaccharide. One 4-deoxyhexulosonic acid, of unknown configuration, is known and is a component of the E. coli K3 capsular polysaccharide. "... 

RG-n, Rhamnogalacturonan II Kdo, 3-deoxy-D-manno-octulosonic acid Dha, 3-deoxy-D-/yxo-heptulosaric acid aceric acid, 3-C- carboxy-5-deoxy-L-xylose TMS, per-0-trimethylsilylated methyl glycosides. 

Stevenson, T. T., Darvill, A. G., Albersheim, P. (1988). 3-Deoxy-D-/yxo-2-heptulosaric acid, a component of the plant cell-wall polysaccharide rhamnogalacturonan-II. Carbohydr. Res., 179, 269-288. 

The structure contains a number of uncommon sugars, including Kdo (Figure 1.9), apiose (Figure 1.15), Dha (2-keto-3-deoxy-D-/yxo-heptulosaric acid) and aceric acid, AceA (3-carboxy-5-deoxy-L-xylose) (Figure 4.64). Side-chain structures are shown in Figures 4.63, 4.65 and 4.66. 

Figure 4.64 Straight-chain Fischer structures for the pectin sugars Dha (2-keto-3-deoxy-/rxo-heptulosaric acid) and aceric acid (3-carboxy-5-deoxy-L-xylose).

B. Becker, K. Hard, M. Melkonian, J. P. Kamerling, and J. F. Vliegenthart, Identification of 3-deoxy-matmo-2-octulosonic acid, 3-deoxy-5-0-methyl-mawio-2-octulosonic acid and 3-deoxy-/yxo-2-heptulosaric acid in the cell wall (theca) of the green alga Tetraselmis striata Butcher (Prasinophyceae), Eur. J. Biochem., 182 (1989) 153-160. 

An unique structure represents DHA (6), being a rare dicarboxylic (heptulosaric) acid [7], It was isolated from the LPS of Actinobacter calcoaceticus [8] and other bacteria belonging to Rhizobiaceae [8]. Besides of bacteria, DHA has been so far observed only in plants, as a component of their rhamnogalacturononan [9] and as a cell-wall component of algae [10]. 

The lyxo isomer of 181 submitted to methoxymercuration-demercuration reaction provided the epimeric compound 188 with full regio- and stereoselectivity [120a]. Its transformation to the corresponding heptulosaric acid derivative 189 (Scheme 40) was easily accomplished applying KBr/TEMPO/NaOCl assisted oxidation. 

Based on the above route involving also an inversion of configuration at the desired (selected) carbon atoms, all the isomeric (arabino, lyxo, xylo, ribo) heptulosonic and heptulosaric acids have been achieved [120c]. 

This ketene dithioacetal protocol was employed to deliver all the isomeric 3-deoxy-heptulosonic and heptulosaric acids, as well as their 2-deoxy counterparts [130]. Further, by this route the synthesis of KDO and 2-deoxy-KDO was accomplished [133]. This methodology was also utilized for direct construction of naturally occurring KDO disaccharides [134]. 

Deoxy-2-heptulosaric acid - 3-Deoxy-araA io-heptulosonic add... 

Small complex polysaccharide containing apiose, 2-0-methyl-L-fucose, 2-0-methyl-D-xylose, acetic acid, Penta-Ac, 3-deoxy-D-/yxo-heptulosaric acid and other sugars depending on source. Obt. by the action of liquefying enzymes on apple, tomato and carrot juice pectin. The main nondegraded soluble polysaccharide component of the juice. Also present in various other plant products, e.g. leaves of Panax ginseng (ginseng). 

Di- 0 -isopropylidene, D-154 7-Deoxy-gfl/flcfo-heptopyranos-6-ulose a-D-/orw, D-154 3-Deoxy-2-heptulosaric acid AR,SR,SS)-form Me p-pyranoside, di-Ac, di-Me ester, D-166... 

Deoxy-2-heptulosaric acid AR,5S,SS)-form Me a-pyranoside, di-Ac, di-Me ester, D-166... 

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