Glucometasaccharinic acids

This stopping or stabilization reaction with cellulose was presumed to involve a saccharinic acid rearrangement of the reducing group on the terminal D-glucose residue. This mechanism was confirmed by the formation of D-glucometasaccharinic acid, which still remained attached as the terminal unit (73). The stopping reaction is presented in Scheme 13. 

The 3-deoxyaldonic acids (metasaccharinic acids) arise by alkaline treatment of monosaccharides, especially those substituted at C-3.288 They have also been obtained from (1 - 3)-linked oligo- and polysaccharides. The most common ones are 3-deoxy-D-n Z>o-hexonic acid (a-D-glucometasaccharinic acid, 109) and 3-deoxy-o-arabino-hexonic acid (jS-D-glucometasaccharinic acid, 110), which can most conveniently be... 

S. Lewak and L. Szabo, Phosphorylated sugars. Part VIII. The synthesis of phosphorylated glucometasaccharinic acids, J. Chem. Soc., (1963) 3975-3980. 

Fig. 2-34. Stopping reaction. 1 —>2, 1,2-Enediol formation 2 — 3, j3-hydroxy elimination 3 —> 4, tautomerization 4 —> 5, benzilic acid rearrangement leading to a glucometasaccharinic acid end group, (cf. Fig. 2-33.)...

It is interesting that Nef assigned the correct configurations to the D-galactometasaccharinic acids, as well as to the D-glucometasaccharinic acids, on the basis of analogies between the optical rotations of n-tartaric acid, the 2,4-dihydroxyglutaric acids (obtained by oxidation of the five-carbon metasaccharinic acids), and the 2,3,5-trihydroxyadipic acids (obtained by oxidation of the six-carbon metasaccharinic acids). 

The epimerie D-glucometasaccharinic acids were first isolated by Nef from the interaction of n-glucose and hot, concentrated sodium hydroxide. D-Glucose is isomerized and smoothly degraded under these conditions to a mixture of saccharinic acids, in a yield of over 80%. 

A recently developed method for preparing the epimerie D-glucometasaccharinic acids is based on the action of lime-water on the seaweed polysaccharide, laminarin. The mixed D-glucometasaccharinic acids are obtainable from this source in practically pure condition, as their calcium salts, after separation from unchanged polysaccharide. The directions for their preparation from insoluble laminarin follow. 

Six-carbon Metasaccharinic Acids 3-Deoxy-n-ara6fno-hexonic acid ( /9 -D-glucometasaccharinic acid) anilide 123-124 -63(95%EtOH) 85... 

Machell and Richards succeeded in isolating 3-deoxy-D-en/fkro-hexos-ulose (52), the postulated dicarbonyl intermediate in the formation of d-glucometasaccharinic acid (68) in the alkaline degradation of 3-0-sub-stituted D-glucose derivatives, from 3-0-benzyl-D-glucose (67). 

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