Mannaric acid

Aldaric acids or their derivatives undergo ready epimerization in pyridine. Alkaline treatment of 4-O-methyl-D-glucuronic acid in the presence of air affords 4-O-methyl-D-glucaric and -D-mannaric acids as well as lower O-methylaldaric acids.262 The two diastereo-isomeric 3-deoxy-2-C-(hydroxymethyl)pentaric acids obtained from... 

Proof of the structure of the uronic acid was obtained by Hirst, Jones and Jones,46 who isolated the methyl glycoside methyl ester by methyla-tion of the products from the graded methanolysis of alginic acid. The tri-O-methyl-D-mannuronic acid was converted to the diamide of 2,3,4-tri-O-methyl-D-mannaric acid, which had previously been prepared from... 

The acetylation of 2-(D-ara6o-tetrahydroxybutyl)benzimidazole is reported to yield a tetraacetate 7 2-(D-paiacto-pentahydroxypentyl)-benzimidazole, on the other hand, apparently forms a hexaacetyl derivative,30 and the dibenzimidazole from D-mannaric acid, which contains four hydroxyl and two imino groups, forms a hexaacetyl derivative.22,28 It is not clear from these isolated cases whether N-acetylation as well as O-acetylation is to be expected or not. 

The coordination behavior of molybdenum(VI) with D-mannaric acid 64 is similar to that with galactaric acid two molybdenum atoms are bonded either by the two a-alkoxidocarboxylato moieties of fourfoldly deprotonated D-mannaric acid or by the aikoxido functions of the C1-C3 subset and the C4—C6 subset, respectively, of entirely deprotonated D-mannaric acid. Due to the f/ireo-conflguration of the central diol residue, a threo complex is established in neutral solutions with a molar ratio of Mo ligand of 4 1 instead of an erythro complex which was observed with galactaric acid (compare structure 20 and 14 (O Fig. 2), respectively) [75]. The latter threo complex as well as a complex with the a-alkoxidocarboxylato moieties as chelation sites is also formed by tungsten(VI) [76]. 

Dicarboxylic acid HOOC(CHOH)nCOOH Aldaric acid Glucaric acid Saccharic acid) Mannaric acid Mannosaccharic acid)... 

The deamination reaction of 2-amino-2-deoxy aldonolactones is also of interest. 2,5-Anhydro-D-mannaric acid has been obtained from the treatment of 2-amino-2-deoxy-D-mannonolactone, epichitosaminic lactone, with nitrous acid and subsequent oxidation of the product with nitric acid. This indicates that the reaction proceeds with a net retention of configuration, as for the corresponding free acid discussed later (p. 56). Similar treatment of 2-amino-2-deoxy-D-idonolactone, d-dextro-xylo-hexosaminic lactone, provides 2,5-anhydro-D-gularic acid, which is the epimer of the product derived from the free acid. " ... 

Similarly, D-mannaric acid 1,4 6,3-dilactone (12) gave, under the same conditions, the corresponding O-methylated, unsaturated esters 13 and 14. 

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