Malonic acid naturally occurring

The telomer 137, obtained by the reaction of butadiene with malonate, is a suitable compound for the syntheses of naturally occurring dodecanoic acid derivatives, such as queen substance (I38)[l 7], one of the royal jelly acids (139)[I18], and pellitorine fl40)[ll9]. 

Maleonitrile, l,2-dicyanoethylene-l,2-dithio-metal complexes, 6, 147 Malic acid metal complexes geochemistry, 6, 867 naturally occurring, 2,962 Malonic add... 

Elaboration of the side-chain of the salicylaldehyde (376) coupled with a Knoevenagel condensation enabled a number of naturally occurring coumarins such as xanthyletin (377) to be prepared (71CJC2297). The use of C-labelled malonic acid leading to coumarins labelled at C-3 enhances the potential of this route. 

Synthesis from Ethylene Bromide.—Such an acid is known as a commonly occurring substance in nature and is called succinic acid. It has the composition C4H6O4 and is plainly isomeric with methyl malonic acid. Its constitution as given above is, however, proven by the following syntheses Ethylene bromide, or symmetrical di-brom ethane, which is made by the addition of bromine to ethylene gas, yields by treatment with potassium cyanide a symmetrical di-... 

Naturally occurring sorbic acid may be extracted as the lactone (parasorbic acid) from the berries of the mountain ash Sorbus aucuparia L. (Fam. Rosaceae). Synthetically, sorbic acid may be prepared by the condensation of crotonaldehyde and ketene in the presence of boron trifluoride by the condensation of crotonaldehyde and malonic acid in pyridine solution or from 1,1,3,5-tetraalkoxyhexane. Fermentation of sorbaldehyde or sorbitol with bacteria in a culture medium has also been used. 

Malonic acid 1,3-propanedioic acid a naturally occurring compound C—CH2 C ... 

Biological synthesis of fatty acids is analogous to the malonate synthesis of carboxylic acids. The enolate carbanion from malonate acts as a nucleophile in a nucleophilic substitution on the acetyl-CE followed by decarboxylation. Each series puts the three-carbon malonate on the ACP and then decarboxylates the substitution product, resulting in lengthening of the carbon chain by two carbons at a time. Naturally occurring fatty acids are even numbered carboxylic acids. 

The facts that radioactively labeled acetate and malonate label acetylenes in the same manner as fatty acids and that few branched-chain acetylenic compounds are known strongly suggest that naturally occurring acetylenes are derived from fatty acids. Additionally, many acetylenic compounds with a Z double bond have the double bond in the same position as the double bond of oleic acid. In a similar manner to fatty acids, introduction of double bonds into acetylenic compounds requires molecular oxygen. Although the triple bond is usually introduced into a position where a double bond would be expected, in some instances no prior double-bond formation is observed. The enzymes responsible for the introduction of triple bonds have been little studied. 

Inhibitors of the Citric Add Cycle. Many compounds have been found to inhibit various steps of the citric acid cycle. Two inhibitors are of particular importance. Arsenite specifically inactivates a-ketoglutarate oxidation. This compound has a similar effect on pyruvate oxidation, and it is now believed that arsenite sensitivity is characteristic of systems containing disulfide groups, as found in lipoic acid. Malonate is a competitive inhibitor of succinate oxidation. Besides its usefulness in studies in which it is desirable to prevent further oxidation, this inhibition was instrumental in developing our current concept of competitive inhibition, since the similarity of structures is striking, and the competitive nature of the reaction is easily demonstrated. The specific inhibition of aconitase by fluorocitrate has already been mentioned. Succinate oxidation is inhibited by naturally occurring C-4 dicarboxylic acids in particular oxalacetate has been found to inhibit succinate oxidation in systems that permit oxalacetate to accumulate. 

The decomposition pathways of DBNPA described by Exner et al. (1973) are shown in Figure 21. Hydrolysis ends with oxalic acid which oxidizes slowly to CO2. The reaction of DBNPA with nucleophiles leads to malonic acid, which is just as oxalic acid a naturally occurring dicarboxylic acid it may further degrade to acetic acid and CO2. 

Incorporation experiments proved that lunularin (595) and lunularic acid (598) were biosynthesized by the shikimate-malonate pathway 288, 290). The co-occurrence of (595) and (598), and the presence of a lunularic acid decarboxylase in Lunularia cruciata and Conocephalum conicum indicated that a decarboxylation step was involved in forming naturally occurring C-14 stilbenes and their dihydro products 290, 292). 

According to the acyl-polymalonate hypothesis, chain-starter units other than acetate may be involved in the biosynthetic process (c/. Scheme 1). In this connection, the naturally occurring stilbenes and derivatives are produced by condensation of a cinnamate unit with three malonate units followed by aldol condensation of the enzyme-bound P-triketo-ester intermediate (77). " Secondary transformations (p. 183) may also occur at a pre-aromatic or postaromatic stage in the biosynthesis. Previous attempts to demonstrate the intermediacy of P-triketo-esters in the biosynthesis of stilbenes resulted in the reported conversion of cinnamoyltriacetic acid (77 R = H, as acid) into pinosylvin (79) by acetone powders prepared from leaves of a mutant of Eucalyptus sideroxylon. However, a subsequent report has indicated that this conversion cannot be repeated and this has prompted the explanation that P-polyketo-ester intermediates are bound to the enzyme and do not occur in the free state. Several difTerent preparations of acetone powder from E. 

Decarboxylation of malonic acid derivatives is a well studied process in the biosynthesis of biomolecules such as long-chain fatty acids and polyketides. A decarboxylase that exhibits enantioselectivity for substituted malonates would be useful for producing ophcally active carboxylic acids, hi fact, malonyl-CoA decarboxylase does catalyze an enantioselective decarboxylation (Figure 3.2) [5], but malonyl-CoA is an unsuitable precursor for optically active substances. Instead, we focused on the prochiral-activated compoimd arylmalonate, an intermediate of malonic ester synthesis, to develop a method for enantioselective decarboxylation. Malonates are stable at room temperature but readily decompose to arylacetate and CO2 at high temperatures. This suggests that the decarboxylation of arylmalonate may occur naturally if arylmalonate acts as a substrate for a decarboxylase. 

Simple organic molecules such as small carboxylic acids (oxalate, acetate, malonate, citrate, etc.), amino acids and phenols are all ligands for metals. Such compounds may all occur as degradation products of organic matter in natural waters. The complexes formed are typically charged hydrophilic complexes. The stability of the metal complexes with these ligands is, however, moderate in most cases. Model calculations including such compounds at realistic concentrations indicate that their effects on speciation are relatively small [29],... 

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