2- Hydroxybutanedioic Acid

Chiral, nonracemic, monocyclic y-lactams have been alkylated. One such lactam, 5-ethoxy-4-hy-droxy-l-isopropyl-2-pyrrolidone (5), is obtained as an 82 18 mixture of the (4S,5Jt)- and (4S,5S)-isomers from (S )-2-hydroxybutanedioic acid (4), via the crystalline, enantiomerically pure (A)-3-acetoxy-1 -isopropyl-2,5-pyrrolidinedione, in a five-step procedure with 57 % overall yield19,20. 

The formation of 2-oxopyran-5 -carboxylic acid (coumalic acid) from 2-hydroxybutanedioic acid (malic acid) is described in detail (63OSC(4)20l) and involves the decarbonylation and dehydration of the hydroxy acid. The formylacetic acid so formed then undergoes selfcondensation. This synthesis is an example of the Pechmann reaction usually associated with the synthesis of coumarins (benzopyran-2-ones). It will be observed that this route leads to pyran-2-ones which carry identical substituents at the 4- and 6-positions. 

Chapter 18 Carboxylic Acids and Their Derivatives 18.10 (a) 3,7-Dimethyloctanoic acid (b) 2-Aminopentanoic acid (c) Hexanoic acid (d) 2-Hydroxybutanedioic acid... 

DL-Malic Acid Hydroxysuccinic Acid 2-Hydroxybutanedioic Acid... 

The hydration of fumaric acid [( )-butenedioic acid, 1 R = H] to (S)-2-hydroxybutanedioic acid (2) is catalyzed by the enzyme fumarase. This reaction can be run even on an industrial scale, exploiting the fumarase activity of immobilized microorganisms77. Unfortunately, the substrate spectrum of fumarase is very narrow. Nevertheless, (Z)-2-chlorobutenedioic acid (3, R = Cl) could be diastereo- and enantioselectively hydrated to (2S,3/ )-2-chloro-3-hydroxybu-tanedioic acid (4) on a 50-gram scale, employing commercially available pig heart fumarase [EC 4.2.1.2.]78. 

Hydroxybutanedioic acid occurs naturally in apples and other fruits. Rank the labeled protons (Ha-HJ in order of increasing acidity and explain in detail the order you chose. 

N-(2-diethylaminoethyl)-5-[(Z)-(5-fluoro-2-oxo-1 H-indol-3-ylidene)methyl]-2,4-dimethyl-1 H-pyrrole-3-carboxamide (25)-2-hydroxybutanedioic acid... 

Fumaric acid is converted to L-malic acid (6 -2-hydroxybutanedioic acid) by the Qnzymefumarase. The hydroxyl group is added stereospecifically from the si face of the double bond. 

Malic acid (INS No 296 FW 134.09) Chem. name dl malic acid 2-hydroxybutanedioic acid, hydroxy succinic acid. Malic acid is the second most popular general purpose food acid, although only less than one-tenth of the quantity of citric acid is used in food. The functional uses include acidity regulator and as a flavoring agent [46]. The ADI is not limited. The usage of malic acid is similar to that of citric acid. 

From the Latin malum (apple). Malic acid (2-hydroxybutanedioic acid), found in apples, can be dehydrated on heating to give maleic acid. 

Malic acid (2-hydroxybutanedioic acid) is a 4-carbon dicarboxylic acid, and its structural formula is given in Fig. 9.1. It is an intermediate in the tricarboxylic acid (TCA) cycle (Fig. 9.2). Malic acid is extensively used in the food industry as a flavor enhancer and acidulant (Bressler ef al., 2002). Furthermore, it is utilized in pharmaceuticals, metal... 

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