Dihydroxyfumarate

Fenton s reagent. To a solution of tartaric acid or a tartrate add 1 drop of freshly prepared ferrous sulphate solution, i drop of hydrogen peroxide solution and then excess of NaOH solution an intense violet coloration is produced, due to the ferric salt of dihydroxyfumaric acid, HOOC C(OH) C(OH)COOH. 

The reaction of iodate with triose reductone is not only a function of the concentration of the reagents, it is also dependent on the pH of the solution. In solutions of triose reductone more dilute than 10"3M, iodine is set free from iodate, if the pH of the solution is lower than about 3 (55). Dihydroxyfumaric and L-ascorbic acids (26), which also have free ene-diol structures, behave similarly. 

This reaction sequence is a general one for ene-diols. For example, in the same conditions, dihydroxyfumaric acid is oxidized by two moles of periodate, first to a diketone and then to two moles of oxalic acid (25,56). 

Literature reports on synthetic methods for the construction of the pyrimidinone core were very limited. Most of the synthetic strategies toward the densely functionalized core fell into two methodologies, which start from the same amidoxime 13 (Scheme 6.3). Route A is a three-step sequence that involves hydrogenation of 13 to prepare amidine 14. Claisen condensation of commercially available a-benzyloxy acetate and methyl tert-butyl oxalate provides the dihydroxyfumarate... 

Scheme 6.4 Condensation of dihydroxyfumarate derivatives with amidines to pyrimidinone...

Biosyntheses of hexuronic acids and L-ascorbic acid in plants and animals are closely related. Hexuronic acids, L-ascorbic acid, and L-tartaric acid (a possible precursor of dihydroxyfumaric acid) commonly occur together in plants. If a rat is given chloretone (an antispasmodic), both L-ascorbic acid and D-glucuronic acid are excreted in increased quantity.244 Unlike humans, rats can synthesize their own vitamin C, and are therefore independent of outside sources. Here, D-glucose and D-galactose can be utilized, but not D-mannose. 

Dehydrogenation HO COOH Q O COOH 2 jr 2 T +2H20 HOOC OH HOOC 0 Dihydroxyfumaric acid HRP... 

Selective hydroxylation of some aromatic compounds can be achieved using HRP C in the presence of oxygen and dihydroxyfumaric acid (270). This process afforded l-DOPA from L-tyrosine, D-(-)-3,4-dihydroxy-phenylglycine from D-(—)-4-hydroxyphenylglycine, and L-epinephrine (adrenalin) from L-(-)-phenylephrine in yields of up to 70%. 

This enzyme [EC 4.1.1.54] catalyzes the conversion of dihydroxyfumarate to tartronate semialdehyde and carbon dioxide. 

DIHYDROXYACETONE SYNTHASE DlHYDROXY-ACID DEHYDRATASE DIHYDROXYBIPHENYL 1,2-DIOXYGENASE DIHYDROXYFUMARATE DECARBOXYLA.SE... 

Dihydroxymaleic acid (dihydroxyfumaric acid hydrate) [133-38-0] M 148.1, m 155 (dec). Crystd from water. 

Pasta P, Carrea G, Monzani E, Gaggero N, Colonna S (1999) Chloroperoxidase-Catalyzed Enantioselective Oxidation of Methyl Phenyl Sulfide with Dihydroxyfumaric Acid/Oxygen or Ascorbic Acid/Oxygen as Oxidants. Biotechnol Bioeng 62 489... 

Fig. 6.5 FIRP catalyzed hydroxylation of L-tyrosine to L-Dopa in the presence of dihydroxyfumaric acid...

The nuclear hydroxylation of aromatics can be catalyzed by horseradish peroxidase, and with suitably activated substrates synthetically useful yields can be obtained.The reactions are usually carried out at 0 C in the presence of dihydroxyfumaric acid cofactor and a source of oxygen. Thus l-DOPA (102) has been prepared using this system. ... 

Yamazaki, Mason and Piette [63-65] have investigated the mechanism of action of peroxidases using flow ESR apparatus. The peroxidase used (from Japanese turnips) catalyses the oxidation of a number of substrates such as indoleacetic acid, dihydroxyfumarate and triose reductone by hydrogen peroxide. They were able to demonstrate directly the presence of free radical intermediates, a number of which could be identified from their hyperfine structure, and to show a correlation between ESR signal intensity and the kinetics expected for the reaction. This was strong evidence for a mechanism concerning one-electron transfer steps. The steady state concentration of free radicals was proportional to the square root of the enzyme concentration and the main decay route of the radicals was via dismutation. 

Some of the earliest kinetic studies on metal ion-promoted reactions were carried out on metal ion-promoted decarboxylations of j8-oxo acids. The literature on this topic up to about 1974 has been reviewed. Much of the work has centred on oxaloacetic acid (HO2CCOCH2CO2H = H20xac) and its derivatives, a,a-dimethyl oxaloacetic acid and fluorooxaloacetic acid. Studies have also been made with acetonedicarboxylic acid (3-oxoglutaric acid), " dihydroxyfumaric acid, dihydroxytartaric acid, acetosuccinic acid, oxalosuccinic acid and 2-oxalopropionic acid (Figure 6). The decarboxylation of )3-oxo acids is of considerable biological importance, and in a number of cases metalloenzymes are involved. Similarities in the enzymatic and chemical processes stimulated early interest in these reactions as models for the enzymatic systems. 

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