DE679975C - Process for the preparation of methylene ether derivatives of d-xyloseonic acid, their salen and esters - Google Patents

Description

Process for the preparation of methylene ether derivatives of d-xylosonic acid, its salts and esters Of the four theoretically expected pentosonic acids of the general formula CH, OH - CHOH - CHOR - CO -COOH, no representative is described in pure form, and only one of these pentosonic acids, of 1-rinboxylic acid are derivatives, e.g. B. acetone methyl lactolide (Helv. Chim. Acta 17 [z93 [], p. 1003) is known. Furthermore, it is still unexplored which processes can be used most expediently for the preparation of the pentosonic acids, which are quite labile in contrast to the hexosonic acids, and whether the methods which are generally useful for the preparation of hexosonic acids can be used for this purpose, e.g. B. the oxidation of hexosones with bromine water (Neuberg and Kitasato, Biochemische Zeitschrift 207 [r929, pp. 217 to 23o).

It has now been found that the methylene ether derivatives of d-xylonic acid, its salts and esters can be prepared easily and in good yield if the monomethylene ether derivatives of 4-xyloketose are treated in an alkaline solution at the lowest possible temperature with an amount of an oxidizing agent corresponding to approximately two oxygen atom equivalents whose oxidation potential is suitable for converting a primary hydroxyl group into a carboxyl group. The free methylene ether-d-xylosonic acids or their esters are obtained in the customary manner from the salts obtained. The oxidation of monoacetone-d-xyloketose (Journ. Of Biol. Chem. 106 [1934] pp. 603 and 115 [1936], p. 731) is illustrated by the following formulas: Instead of acetone, other ketones, e.g. B. methyl ethyl ketone, cyclohexanone and the like., Can be used.

When obtaining the free monomethylene ether-d-xylonic acids or Their esters from the salts is strongly acidic reaction and temperature increase as much as possible to be avoided, as the methylene ether groups are otherwise easily split off and others Rearrangement and decomposition occur. The esters are therefore expediently from the free acids with diazoalkanes or from the salts with haloalkylenes or alkyl sulfates prepares.

The methylene ether derivatives of d-xylosonic acid and their salts and Esters are intermediates for the production of therapeutically important compounds.

Example 7.9 parts of monoacetone-d-xyloketose are dissolved in a mixture of 4.3 parts of potassium hydroxide and 105 parts of water. A solution of 8.9 parts of potassium permanganate in zoo parts of water is gradually added dropwise to this solution at 0 ° with stirring. Finally, stirring is continued at the same temperature until the permanganate is discolored. The mixture is then heated to 50 ° for about 15 minutes and the manganese dioxide is separated off. The brown solution is neutralized with sulfuric acid to such an extent that phenolphthalein is no longer reddened, but litmus is still clearly blued. The syrup is then evaporated in vacuo at a bath temperature of 40 °. This is dissolved in methanol with heating and separated from the dark salts which precipitate by filtration. The residue obtained by evaporating the methanol solution is boiled several times with absolute alcohol. The solutions in absolute alcohol are clarified with a little purest charcoal and strongly evaporated in a vacuum. Plenty of crystal flakes fall out. The resulting potassium salt of 2,3-monoacetone-d = xylosonic acid melts at 2.64 to 265 ° with decomposition. It is very light in water, good in methanol, very difficult in absolute alcohol, and almost insoluble in acetone.

For the preparation of the free 2,3-monoacetone-d-xylonic acid, 1 Part of pure potassium salt in the exact amount of normal aqueous sulfuric acid required dissolved in the cold and the solution immediately mixed with zoo parts acetone. That precipitated potassium sulfate is separated off and the acetone solution is evaporated in vacuo. The residue crystallizes immediately. It is made from acetone, to which benzene has been added is recrystallized. The 2,3-monoacetone-d-xylosonsänre forms fine needles that melt at 174 to 175 °.

[a] D "= - I2 ° (c t = 1.2 in acetone).

The 2,3-monoacetone-d-xylosonic acid methyl ester crystallizes from petroleum ether. It melts at 79o.

Claims (1)

PATENT CLAIM: Process for the preparation of methylene ether derivatives of d-xylosonic acid, its salts and esters, characterized in that monomethylene ether derivatives of d-xyloketose are treated in an alkaline solution at the lowest possible temperature with the amount of an oxidizing agent corresponding to approximately two oxygen atom equivalents, the oxidation potential of which is suitable, converting a primary hydroxyl group into a carboxyl group, and optionally obtaining the free acids or their esters from the salts obtained in this way in the customary manner, avoiding the simultaneous use of strongly acidic reactions and elevated temperatures.