Hexonic acid preparation

The preparation of sirupy 1-methyl-D-glucosone and crystalline 1-phenyl-D-glucosone (XXII), via the corresponding 2,3 4,5-di-0-isopropylidene derivatives, by Ohle and his colleagues61 64 (by treatment of 2,3 4,5-di-O-isopropylidene-2-oxo-D-arabmo-hexonic acid (XXI) with the requisite... 

Oxidation with Bromine Water.—With 2- or 3-desoxy-hexoses or -pentoses, oxidation by bromine water follows the usual course and converts them into the corresponding 2- or 3-desoxy-hexonic or -pentonic acids. The oxidation is more rapid if the hydrobromic acid that is produced in the reaction is removed as it is formed, by barium or calcium carbonate227 or barium benzoate.228 In view of the sensitivity of 2-desoxysugars to prolonged contact with mineral acids, it is advantageous to adopt this latter procedure for their oxidation.112 Sometimes for the preparation of desoxy -pentonic and -hexonic acids the method of oxidation (or slight modifications thereof) introduced by Goebel229 is employed. 

Deoxy-D-xy/o-hexonic acid (a-D-galactometasaccharinic acid, 111) can be prepared from D-galactose 289 the / -(d-lyxo) isomer can be isolated in smaller amounts from the mother liquors. 

H. B. Wood, Jr. and H. G. Fletcher, Jr., 2-Deoxy-D-ribose. VI. The preparation of derivatives of 3-deoxy-D-riAo-hexonic acid and 3-deoxy-D-araWno-hexonic acid therefrom. Some observations on the Kiliani synthesis, J. Org. Chem., 26 (1961) 1969-1973. 

Diethoxycarbonylallene, an active dienophile and ethoxycarbonylketen equivalent, has been used to prepare (83), which is a key intermediate for projected syntheses of antibiotic C-nucleosides. Treatment of such 2,3-dideoxyald-2-enonic acid esters as (84) with sodium methoxide yielded 3,6-anhydro-2-deoxy-hexonic acid esters [e.g. (85)] from an internal Michael reaction on the deacetylated derivative. ... 

Aldonamides are readily prepared by reaction of lactones with liquid ammonia (86,99,100), with ammonium hydroxide (101,102), or by bubbling ammonia gas into alcoholic solutions of the sugar lactones (103-104). Aldonamides of the tetronic adds are stable in aqueous solution (105), but penton- or hexon-amides are hydrolyzed, as shown by the change of the optical rotation of the amide solutions (106). The hydrolysis is catalyzed by acids and bases, and the product was the ammonium salt of the aldonic acid. 

A further study of the use of the Arndt-Eistert reaction in carbohydrate chemistry examined the reactions of the diazoketone (247) (prepared from a-D-glucoisosaccharinic acid), which gave mainly the orthoester (248) and both the ( )- and (Z)-isomers (249) of a 2,3-unsaturated methyl hexonate derivative on treatment with silver oxide in methanol. The 3-C-methylene derivative (248) is a useful precursor of 4-deoxy-3-C-methyl-D-hexoses. 

In the next year (Foster and Schmidt, 1923), the investigation was extended to other proteins casein, fibrin, and red blood cells. Instead of adding sulfuric acid to the cathode compartment, carbon dioxide w as bubbled through it. The middle compartment was cooled by running water and stirred. The completeness of the separation depended upon the time employed, but, for preparative purposes, it was not found worth while to wait for more than 90 % of the hexone bases to be transported to the cathode. After a second run, this solution contained 98.5 to 100% basic nitrogen. 

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