Patricia Szabó

Synthesis and behaviour under acidic conditions of 2-deoxy-D-arabino-hexopyranose and 3-deoxy-2-ketoaldonic acids bearing O-phosphono or O-glucosyl substituents at position β to the carbonyl function

Methyl 4-O-phosphono- and 4-O-(β-D-glucopyranosyl)-3-deoxy-β-D-erythro-2-hexulopyranosidonic acids, and 3-O-phosphono-, and 3-O-(β-D-glucopyranosyl)-2-deoxy-α-D-arabino-hexopyranoses have been synthesised and their behaviour in acidic media examined. At 100 °C, release of inorganic phosphate from the 4-O-phosphonohexulopyranosidonic acid is faster at pH 3–6 than at pH 0–1 and occurs through an elimination initiated by proton transfer. Phosphate release from the 3-O-phosphono-2-deoxy-hexopyranose occurs by a similar mechanism, but is much slower. Treatment at 100 °C with acetic acid of pH 3.4 causes release of glucose from the 4-O-glucosylated-3-deoxy-hexulopyranosidonic acid but not from the 3-O-glucosylated-2-deoxy-hexopyranose.

The reaction of malonaldehyde with periodate, and its application to the determination of vicinal diols in deoxy sugar derivatives

Abstract In dilute solution and at pH 3 to 5, triose reductone reduces three molar equivalents of periodate to iodate, and forms two molar equivalents of formic acid and one molar equivalent of carbon dioxide; iodine is not liberated in the process. Other ene-diols react similarly. At higher concentrations or lower pH values, iodine is liberated in all cases. Conditions in which malonaldehyde would react with stoichiometric amounts of periodate could not be found in the pH range of 1 to 8. It is shown that enolisation of malonaldehyde is faster than its reaction with periodate, and it was observed that malonaldehyde undergoes an unidentified chemical reaction at those pH values (3 to 5) where most periodate oxidations are carried out. At 4° in 0.1N sulphuric acid, malonaldehyde does not react with periodate over long periods of time, whereas glycol cleavage proceeds normally; therefore vicinal diol groups of deoxy sugars, deoxy sugar alcohols, and similar compounds can be titrated quantitatively in these conditions. The malonaldehyde formed can be estimated simultaneously by a calorimetric method, no standard being required. Syntheses of 3-deoxy- d - xylo -hexitol and of its pentabenzoate are described.

Phosphorylated sugars. Part 25. Synthesis and behaviour in acidic media of 2-acetamido-2-deoxy-D-glucose 4- and 6-phosphates and of a ‘Lipid A’ analogue

With the aid of 2-acetamido-2-deoxy-D-glucose 4- and 6-phosphates and of 2-amino-2-deoxy-D-glucose-6-phosphate, for all of which new and efficient syntheses are described, it has been shown that during treatment of 2-acetamido-2-deoxy-D-glucose 4-phosphate and of the model 2-hydroxyethyl 2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-β-D-glucopyranoside 4-phosphate (which has also been synthesised) under conditions of acidic hydrolysis used in the determination of the structure of ‘Lipid A’ preparations from bacterial endotoxins, migration of the phosphate group from position 4 to position 6 takes place. Conditions are described in which the N-acetyl group is completely removed whilst the extent of phosphate migration is very small. Longer heating times in the same conditions are required to effect almost complete removal of the N-(3R)-3-hydroxytetradecanoyl group from the glucoside, but again very little phosphate migration occurs. The amount of inorganic phosphate formed after removal of the amide-bound substituent from the two 4-phosphates (7.5 and 15.4% respectively) was superior to that formed from N-acetylglucosamine 6-phosphate (2.4%).

Phosphorylated sugars. Part XVIII. Synthesis of D-glycero-D-gulo-heptose 4-(dihydrogen phosphate)

Condensation of benzyl β-D-glycero-D-gulo-heptopyranoside with cyclohexanone gave the 2,3:6,7-di-O-cyclohexylidene derivative, the structure of which was established by mass spectrometry of its benzoate. Phosphorylation of the dicyclohexylideneheptoside, followed by acidic hydrolysis to remove the cyclohexylidene groups, yielded the benzyl heptoside 4-phosphate, which was de-O-benzylated by hydrogenolysis.

Reaction of methyl β-d-glycero-l-manno-heptopyranoside with cyclohexanone: Synthesis of the 4- and 6-methyl ethers of d-glycero-l-manno-heptitol

Abstract Acid-catalysed condensation of methyl β- d -glycero- l -manno-heptopyranoside with cyclohexanone yielded an approximately 3:1 mixture of the 2,3:6,7- and 2,3:4,7-di-O-cyclohexylideneheptosides (1 and 2), which could be separated either as their benzoates (3 and 4) or as their methyl ethers (5 and 6). The latter compounds afforded the 4- and 6-methyl ethers (7 and 8) of d -glycero- l -manno-heptitol.