Hexosulose structures

Deoxyaldosuloses are capable of existing in numerous ring modifications. For 3-deoxy-D-erythro-hexosulose, El-Dash and Hodge43 found that, of the 16 possible ring-forms (excluding enolic structures), evidence could be obtained for 11, although only 6 were stable in anhydrous pyridine. These varied ring-structures, and the many acyclic forms possible, introduce alternative pathways for dehydration to the same or different products and, where the structures are nonreactive, these forms would affect the kinetic pattern of the mechanism thus, they would influence the reaction rate and product distribution. 

All of the above reactions are consistent with structure (18), or the corresponding pyranose (20) or furanose (21) forms, for 3-deoxy-n-erytAro-hexosulose. There is no evidence that an appreciable proportion is in an enolic form. For such a form to be stabilized, the double bond must be conjugated with the carbonyl group at C-1, forming the chromophore —HC=COH—CH=0, which shows a maximum near 260 m/i. No absorption was detected in that region. ... 

Ingles heated a solution of n-glucose, sodium sulfite, and bisulfite, removed the cations, and steam-distilled the residue. The product, free of carbonyl-bisulfite addition compounds, was chromatographed on an ion-exchange resin, giving a sulfonic acid. This acid yields a crystalline brucine salt and phenyl- and (2,4-dinitrophenyl)-osazones. The osazones consume 1 mole of periodate per mole, liberating 1 mole of formaldehyde but no formic acid. The (2,4-dinitrophenyl)osazone also forms a diacetate. The acid is oxidized by sodium hypoiodite, taking up 1 mole of oxidant per mole. From these reactions and the possible reaction mechanisms for its formation, structure (41), a 3,4-dideoxy-4-sulfo-n-hexosulose, was proposed for the sulfonic acid. ... 

The structure of 3-deoxy-D-erythro isomer, from the formation of osazones, of 5-(hydroxymethyl)-2-furaldehyde with acids, and of metasac-charinic acids with alkali. ... 

Hexosulose hydrazones and the mixed osazones react with diazotized aniline to give formazans, and with hydrogen peroxide to give pentonic acids. Unlike the mixed osazones obtained by transhydrazonation, the derivatives obtained from the glycosulose hydrazones are pure, uncontaminated compounds, and the positions of their hydrazone residues are well established. Thus, they afford remarkable possibilities, not only in the preparation of new types of compound, but also in enabling the reaction of osazones to be followed more closely, as in the case of triazole formation," and in studying the structure of anhydro-osazones. ... 

---