Fructuronic acid

The major chloroform extractible product from the decomposition of 1-deoxy-l-dibenzylamino-D-fructuronic acid in pH 6.0 buffer is 4-hydroxy-5-methyl-3(2/7)-furanone [78], Treatment of the same Amadori compound in 2N sulfuric acid gives 2-furaldehyde [79],... 

Platinum-catalyzed oxidation of methyl a-D-fructofuranoside (43) with oxygen is selective for C-6, and fructuronic acid (44) was obtained in 80% yield.151... 

The finding that the furanone is produced from an Amadori compound was interesting in that it permitted us to test, for the first time, the effect of pH on the products of the reaction. This is not possible using a hexose- derived Amadori compound, because the end products are not stable. The product of 1,2-enolization (3-deoxyosone intermediate) is HMF, which is stable, but the product derived from 2,3 enolization (1-deoxyosone intermediate), maltol and isomaltol are not stable in aqueous solution and thus cannot be detected and measured accurately. In our experiment (Scheme 6), we prepared 1-deoxy-dibenzylamino (13), and -benzylamino (12) D-fructuronic acids, as well as... 

Hatanaka and Ozawa studied oligogalacturonate lyases from Erwinia aroideae (54) and a Pseudomonas species (55), which are apparently similar to the one described by Moran et al. (53). With the Erwinia enzyme polygalacturonic acid was degraded more slowly than oligogalacturonate, and unsaturated oligogalacturonates were attacked the most rapidly. The unsaturated dimer forms two molecules of 4-deoxy-5-keto-D-fructuronic acid. The process by which the unsaturated monomer is converted to this product is not known. Ca was not required for activity. 

The Pseudomonas enzyme diflFered from the Erwinia enzyme in that saturated oligogalacturonides were degraded as rapidly as the corresponding unsaturated uronides activity was maximal with tetramers, follower by trimer, dimer, and then polymer and Ca stimulated activity. With a purified enzyme preparation the reaction product from unsaturated digalacturonic acid was 4-deoxy-5-keto-D-glucuronic acid with crude extract a mixture of this acid and 4-deoxy-5-keto-D-fructuronic acid resulted. 

Derivative of l-deoxy D-fructuronic acid m.p., "C. [a]n, degrees Rotation solvent Refer- ences... 

The formation of 2-furaldehyde on acid-catalysed dehydration, etc., of 1-benzyl-amino-l-deoxy-D-f/ireo-pentulose and l-benzylamino-l-deoxy-o-fructuronic acid has been studied in isotopically labelled water (either acidified deuterium oxide or tritiated water).The pattern of labelling of the 2-furaldehyde derived from the latter compound is consistent with a mechanism involving the decarboxylation of a Py-unsaturated carboxylic acid intermediate (see also p. 136). 

Hicks, K.B. Harris, D.W. Feather, M.S. Loeppky, R.N. Production of 4-hydroxy-5-methyl-3(2H)-furanone, a component of beef flavor, from a 1-amino-1-deoxy-D-fructuronic acid. J. Agric. Food Chem. 1974, 22(4), 724-725. 

Dehydration of 1-deoxy-l-dibenzylamino-D-fructuronic acid at 100 " C and pH 7 yielded 4-hydroxy-5-methyl-3(2/f)-furanone, a flavouring component of beef. The mechanism of formation of the product was examined using labelled substrates and deuterium oxide. 

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