Glucosaccharinic acid

The saccharinic acids formed from hexoses have been especially examined because of the relationships of the a and /8 isomers (C-2 epi-mers). Structures of saccharinic acids derived from D-glucose are glu-cometasaccharinic acid (51), glucoisosaccharinic acid (52), and glucosaccharinic acid (53). The a- and /3- isomers of metasaccharinic acid can reversibly isomerize when exposed to base because of the labile proton at C-2. 

Treatment of D-fructose or 1-O-substituted D-fructose with calcium hydroxide produced only the Q -D-glucosaccharinic acid (2-C-methyl-D-ri-bonic acid) and no jS-D-glucosaccharinic acid (2-C-methyl-D-arabinonic acid). However, when D-fructose was treated with sodium hydroxide, the D-glucosaccharinic acids were not detected. In order to confirm this... 

The nascent, 3-carbon anion liberated from the reducing end of D-mannose-i-14C can participate directly in an aldol reaction, to form hexose-3-14C, but it can only afford hexose-i-14C after isomeriz-ing. Thus, the mixture of radioactive hexoses would be mainly C-3-labeled, and would give radioactive a -D-glucosaccharinic acid labeled principally at C-2 this agrees with the experimental result. The formation of the anion (81) could well enhance this effect by... 

A. Ishizu, B. Lindberg, and O. Theander, l-Deoxy-D-eryt/jro-2,3-hexodiulose, and intermediate in the formation of D-glucosaccharinic acid, Carbohydr. Res., 5 (1967) 329-334. 

The presence of a methyl group and of a branched, carbon chain in o -D-glucosaccharinic acid was established by Krliani. Oxidation of o -D-glucosaccharinic lactone with silver oxide gave a mixture of acids... 

The disposition of the functional groups in a -D-glucosaccharinic acid was also established by Kiliani. Reduction of saceharon with hydriodie acid and red phosphorus gave the known, crystalline DL-(2-methylglutaric... 

Confirmation of this structure for a -D-glucosaccharinic acid was obtained by Liebermann and Scheibler when they demonstrated that the known DL-(2-methylvaleric acid) [DL-(methylpropylacetic acid)] was also formed, in low yield, in the reduction of a -D-glucosaccharinic lactone to the 2-methylvalero-l,4-lactone. Moreover, under more strenuous conditions of reduction with hydriodic acid and red phosphorus (in a sealed tube at 200°), the DL-(2-methylvaleric acid) is the principal product. 

If the two lowest asymmetric carbon atoms possess the D-erythro configuration, a -D-glucosaccharinic acid must be either 2-C-methyl-o-arabmo-pentonic acid or 2-C-methyl-D-ribo-pentonic acid. The initial choice between these two possibilities was made by Nef, who chose the D-arabino configuration because of similarities between certain alkaloid salts of the saccharinic acid and the corresponding salts of n-arabinonic acid. However, subsequent developments make the D-ribo configuration appear the more... 

The epimer of the known o -D-glucosaccharinic acid has not been detected among the products of the D-hexose-alkali reaction, although its concurrent formation is to be expected. 

The successful degradation of o[ -D-glucosaccharinic acid to a 1-deoxy-pentulose has apparently not been recorded. Experiments in the author s laboratory have indicated that the oxidation of calcium a -D-glucosac-charinate with hydrogen peroxide and ferric acetate (the Ruff degradation) proceeds normally to yield a reducing product. However, no crystalline derivative of the expected deoxypentulose has been obtained as yet. 

CHjOH CHjOH D -Glucosaccharinic acid 1 CH2OH CH2OH D-Isosaccharinic acid... 

D-glucosaccharinic acid but also D-isosaccharinic acid and Kiliani s para-saccharinic acid might be formed by recondensation of appropriate alde-hydic fragmentation products with a lower-carbon metasaccharinic acid. He proposed that the unbranched metasaccharinic acids, in contrast, are formed by direct dismutation of the isomeric sugars. 

In contrast to the above formation of metasaccharinic acid, fragment recombination appears to be a predominant feature in the formation of the branched-chain a -D-glucosaccharinic acid from D-mannose-l-C plus lime-water. In this case, the radioactivity originally present in Cl of the hexose was found to have become distributed almost entirely between the methyl carbon atom and the tertiary carbon atom of the saccharinic acid, with the latter atom more heavily labeled than the former. In contrast to these observations, the Isbell mechanism, in the absence of compli-... 

From the above considerations, the conclusion may be drawn that, although fragment recombination is implicated in the formation of a -D-glucosaccharinic acid from unsubstituted hexoses, the nature of the fragments involved in the recombination step is not yet known with certainty. 

Six-carbon Saccharinic Acid 2-C-Methyl-D-n 6o( )-pentonic acid ( a -D-glucosaccharinic acid) ... 

Crystalline ammonium, copper, potassium, and rubidium salts have also been reported for a -D-glucosaccharinic acid. 

C-Methyl-aiabmo-pentonic acid. fS-Glucosaccharinic acid... 

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