Pyruvic acid methyl ester

METHYL PYRUVATE (Pyruvic acid, methyl ester)... 

Another pharmaceutical administered as a racemic mixture to treat liver diseases is a-Iipoic acid (Thioctacid). Practically nothing is known about the activity of the individual enantiomers, although naturally occur-ring (+)-a-lipoic acid has an R-configuration. The first enantiomer separation of a-lipoic acid methyl ester was demonstrated on colunms with Lipodex D (Fig. 12,46). a-Lipoic acid is involved in the oxidative decarboxylation of pyruvic add to activated acetaldehyde, which is transferred to coenz3une A to form acetyl coenzyme A. 

Chaetomellic acids have been the subject of a number of syntheses. In 1993, we reported the first synthesis of chaetomellic acid A based on the biogenetic type aldol condensation [73]. The aldol reaction of appropriate fatty acid methyl esters with methyl pyruvate yielded two diastereomeric... 

Glyoxylic acid Et ester, in G-00038 >4-Methyl-l,3-dioxoIan-2-one, M-00160 Pyruvic acid Me ester, in P-00448... 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Only in the case of the pyruvic acid condensation product was it possible to isolate the corresponding ethyl ester under these conditions. This, on mild hydrolysis, reverted to 1-methyl-1,2,3,4-tetrahydro-j8-carbohne-1-carboxylic acid, identical with the starting material, which therefore had the assigned structure 26 (R = CH3) and was not the SchiflF s base 25 (R = CH3). Alkaline hydrolysis of the ester was accompanied by decarboxylation. ... 

Although cinchona-modified Pd showed no enantioselectivity in the hydrogenation of the methyl esters of the unsaturated acids, the hydrogenation of methyl pyruvate occurred with a modest enantiomeric excess... 

Nef prepared acetol in several ways, the more important of which depended upon the reaction between bromoacetone and potassium or sodium formate or acetate, and the subsequent hydrolysis of the ester by methyl alcohol.1 2 Acetol is also formed, together with pyruvic acid, by the direct oxidation of acetone by Baeyer and Villiger s acetone-peroxide reagent.3... 

A solution of 88 g. (l mole) of freshly distilled pyruvic acid, 1 128 g. (4 moles) of absolute methanol, 350 ml. of benzene, and 0.2 g. of -toluenesulfonic acid is placed in a 1-1. round-bottomed flask connected through a ground-glass joint (Note 1) to a methyl ester column shown in Fig. 1 2 (Note 2). The column is fitted at... 

Methyl pyruvate has been prepared from the silver salt of pyruvic acid and methyl iodide,3 and from the free acid by the alcohol-vapor method without a catalyst.4 Pyruvic esters have also been prepared by the dehydrogenation of lactic acid esters.5... 

Medium Boiling Esters. Esterification of ethyl and propyl alcohols, ethylene glycol, and glycerol with various acids, eg, chloro- or bromoacetic, or pyruvic, by the use of a third component such as benzene, toluene, hexane, cyclohexane, or carbon tetrachloride to remove the water produced is quite common. Benzene has been used as a co-solvent in the preparation of methyl pyruvate from pyruvic acid (101). The preparation of ethyl lactate is described as an example of the general procedure (102). A mixture of 1 mol 80% lactic acid and 2.3 mol 95% ethyl alcohol is added to a volume of benzene equal to half that of the alcohol (ca 43 mL), and the resulting mixture is refluxed for several hours. When distilled, the overhead condensate separates into layers. The lower layer is extracted to recover the benzene and alcohol, and the water is discarded. The upper layer is returned to the column for reflux. After all the water is removed from the reaction mixture, the excess of alcohol and benzene is removed by distillation, and the ester is fractionated to isolate the pure ester. 

When the extraction is done with acetone, no methyl abscisate is recovered. Acetone has also been used for recovery of natural IAA esters (18, 32). Another approach to minimize formation of methyl esters has been to extract with hot water (53). Dichloro-methane has been used (71) in preference to methanol or ethanol to minimize the conversion of indole-3-pyruvic acid to IAA. 

The use of proline methyl ester as a chiral auxiliary in the asymmetric synthesis of alanine is shown on the following page. The idea is to start with 2-oxopropanoic acid (pyruvic acid), which has the correct carbon skeleton, and replace tire oxygen on carbon 2 with an amino group and a hydrogen. This must be done in such a manner as to produce only the S-enantiomer of the amino acid, that is, L-alanine. This is accomplished by first attaching a chiral auxiliary, the methyl ester of L-proline, to the acid. In the critical step of the process, the catalytic hydrogenation, the chirality of the... 

Esterification—Continued by azeotropic distillation with benzene, 22, 38 by nitric acid, 22, 65 of desoxycholic acid, 24, 41 of lactic acid, 26, 4 of linoleic acid, 22, 77 of linolenic acid, 22, 83 of pyruvic acid with use of methyl ester column, 24, 72 Ester interchange, 26, 5, 19 between polylactic acid and allyl alcohol, 26, 5... 

An electron transfer mechanism has been proposed to account for the formation of carbon dioxide on irradiation of alkyl pyruvates the yield of carbon dioxide is enhanced by the presence of electron acceptors such as methyl viologen. The dye-sensitized photo-oxidation of a-oxo-carboxylic acids and esters also leads to the production of carbon dioxide. An initial dye-substrate interaction rather than singlet oxygen appears to be responsible for this fragmentation. 

Heterogeneous catalytic hydrogenation of the methyl esters of a-keto acids over modified metal catalysts other than nickel have been studied using a cinchonidine-modified platinum catalyst. " Methyl pyruvate and methyl benzoylformate were hydrogenated to form methyl (R)-lactate and (R)-mandelate with high ee (81-84%). 

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