Glucosaccharinic acid formation

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 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. 

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. 

Shortly after the discovery of Peligot s a -D-glucosaccharin, Dubrun-faut reported that the calcium salt of a monobasic acid resulted from the action of lime-water on maltose. Cuisinier named the acid isosaccharinic acid, after he had prepared from it a crystalline lactone (CeHioOt) isomeric with Peligot s a -D-glucosaccharin. The name was expanded to a -D-iso-saccharinic acid after Nef obtained evidence of the concurrent formation of its epimer, /3 -D-isosaccharinic acid, in the hexose-alkali reaction. 

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