Oxocarboxylic acids

Oxidation, allylic, 56,25 of alcohols, 55, 84 58,122 Oxime ( -allyl ethers, 58,10 S y-(2-Oxobut-3-yl)butanethioate, 55, 129 4-Oxocarboxylic acid esters, 58, 81 S-substituted, 58, 82... 

In the preparation of the oxocarboxylic acid imidazolides in ref. [49] and [53], as well as in their aminolysis, the stereochemical integrity was maintained. 

Hydrazinobenzimidazole derivative 336 was treated with oxocarboxylic acids to give a hydrazone 337 which underwent ring closure to the fused triazinone 338 <2000JME96, 2001JME316>. Reaction with dialkyl oxalate allowed the synthesis of the triazinedione derivative 339 <2001JME4359>. 

The thallium benzoate and thallium 2-oxocarboxylates are available via the reaction of thallium acetate with benzoic acid or the 2-oxocarboxylic acids, due to the lower values of these acids (benzoic acid 4.22, benzoylformic acid 1.2, 2-oxoglutaric acid 31/5.14, pyruvic acid 2.49) compared to acetic acid (4.76) (167). The free acetic acid is distilled off with water as an azeotrope and the thallium carboxylates are obtained in high purity. 

Klingler, F. D. Oxocarboxylic acids, Ullmann s Encyclopedia Industrial Chem., Electronic Release, 7th Ed., chap. 4, Wiley-VCH, Weinheim, 2007. 

Thermal degradation prior to ionization can cause decarbonylation or decarboxylation of the analyte. Decarbonylation, for example, is observed from a-ketocarboxylic acids and a-ketocarboxylic acid esters, whereas decarboxylation is typical behavior of P-oxocarboxylic acids such as malonic acid and its derivatives and di-, tri-, or polycarboxylic acids. 

A. Oxocarboxylic Acids and Derivatives Modified at the Carboxylic Group. .. 258... 

Ring-chain tautomeric interconversions proceeding by intramolecular reversible addition reactions to the C=0 group (Scheme 1) have been well studied, particularly with respect to the 3- and 4-oxocarboxylic acids containing five- or six-membered rings, respectively. Relatively few new investigations have appeared in the literature. 

The chlorides of 2-(2-pyridylcarbonyl)- and 2-(2-quinolylcarbonyl)biphe-nyl-2 -carboxylic acids were obtained (84MI5) only as open-chain isomers. Examples of seven-membered chlorolactone formation in the series of 6-oxocarboxylic acid chlorides are not known. 

In contrast with the oxocarboxylic acids, which readily participate in tautomeric equilibria in solution, their open-chain and cyclic N-unsubsti-tuted and A-monosubstituted amide isomers are more stable. In most cases, the tautomeric equilibrium (Scheme 3) is not observed in neutral aprotic solvents at ambient temperature. In protic solvents, e.g., CD3OD, intercon-... 

HTIB is found to be a suitable reagent for converting 5-oxocarboxylic acids such as 94 into oxolactones 95. The reaction occurs via intramolecular participation of the carboxylic group as shown in Scheme 26 (90TL201). 

The hydrazones derived from (133) and oxocarboxylic acids are thermally very sensitive and decompose immediately at 30 °C to give sulfur, nitrogen, and polymeric material. Decomposition also occurs on treatment with catalytic amounts of both acid and base. 

This type of alkylation also occurs in nature. For example, S-adenosylmethionine (SAM), an important biological methylation reagent, is involved in the biosynthesis of the antibiotic indolmycin and is responsible for the enantioselective C-methylation of an a-oxocarboxylic acid arising from tryptophan3. 

A dissociative first step is anticipated exclusively in photolysis of the endo-cyclic enamide 181 (compare also 80 -a- 85 and 173 -> 174). The reaction is formulated through a ketene intermediate 182. The enamine 183 formed then undergoes hydrolysis to give the oxocarboxylic acid derivative 184 as the product. 

Oxocarboxylic acid esters (78JA4225 85TH1) offer two distinct electrophilic sites to amine (II), the nucleophile. Selective nucleophilic attack at the ester function of (I) may be accomplished by selecting the reaction temperature. 

The present method4 is simple, versatile, and efficient in contrast to eailier methods, which were multistep or preparatively unsatisfactory Various 5-substituted 4-oxocarboxylic acid esters can be prepared by this procedure.4... 

Oxocarboxylic acids, both aliphatic117 and aromatic,41 readily undergo decarbonylation on contact with sulfur tetrafluoride. Rapid evolution of carbon monoxide is observed, even at... 

The reaction of sulfur tetrafluoride with 4-oxocarboxylic acids proceeds via cyclic lactones to give pentafluoroalkanes as the final product. The intermediate lactones may be isolated from reactions conducted under sufficiently mild conditions, e.g. formation of 27 via lactone 26.117... 

Intramolecular carboxy groups can participate as a nucleophile toward a-A3-iodanyl ketones for instance, oxidation of 5-oxocarboxylic acids with PhI(OH)OTs 17 affords a keto-y-lactone in good yields [Eq. (53)] [99]. 

Similar elimination from 1,3,2-dioxathiolane -oxides (cyclic sulfites) has been studied and used along with an in situ trap (DBU/TMSC1) to obtain a tautomeric equivalent of a-oxocarboxylic acid ester (Scheme 14)... 

As can be expected, use of ethyl diazoacetate procides y-oxoesters15) ory-oxocarboxylic acids 16) from enol ethers. Emploging the Julia method with 25 leads to the p,y-unsaturated aldehyde 26. Thus, this sequence establishes an overall a-vinylation of a given aldehyde n 17 18). 

A /3-carboxyl group on the aldehyde also influences the diastereoselection. The high diastereoselectivity observed with the y-hydroxy lactone can be rationalized by a chelated transition state with the carboxylic acid group (Scheme 41).174 2-Oxocarboxylic acids also undergo diastereoselective allylation with cinnamyl bromide to provide the corresponding a-hydroxy acids as a single diastereomer (Equation (19)).1... 

Enders D, Dyker H, Raabe G (1993 a) Enantioselective aldol reactions with a phosphoenolpuryvate equivalent asymmetric synthesis of 4-hydroxy-2-oxocarboxylic acid esters. Angew Chem Int Ed Engl 32 421-423... 

In trifluorooxopropanoic esters, however, the carbonyl function of the ester group is fluorinated by sulfur tetrafluoride, instead of the 0x0 group.In oxocarboxylic acids, both the 0x0 and acid functions react with sulfur tetrafluoride. 

The reaction of ketones with diethylaminosulfur trifluoride or related aminosulfur trifluorides in the presence of fuming sulfuric acid affords vinyl fluorides (see Vol. FlOa, p415). Certain fS-oxo esters and pcntanc-2.4-dione react with diethylaminosulfur trifliioride to give a,/Fdifluoro-a,/i-unsaturated esters and 3,4-difluoropent-3-cn-2-one, respectively. In the reaction of y-oxocarboxylic acids with diethylaminosulfur trifluoride cyclization leads to y-fluorobutyrolactones. ... 

Oxocarboxylic acids, e.g. 23. undergo decarbonylation upon reaction with sulfur tetrafluo-ride." Depending on the reaction conditions, acyl fluorides or trilluoroalkanes are obtained. 

No loss of carbon monoxide occurs in the reaction of 3- and 4-oxocarboxylic acids. By variation of the reaction conditions, 4-oxopcntanoic acid (24) can provide different produets." ... 

The decarbonylation of oxo compounds is also possible. Thermal treatment of polyfluorinated a-oxocarboxylic acids gives polylluorinated carboxylic acids 6. ... 

Banerji B, Conejo-Garcia A, McNeill LA, McDonough MA, Buck MR, Hewitson KS, Oldham NJ, Schofield CJ. The inhibition of factor inhibiting hypoxia-inducible factor (FIH) by beta-oxocarboxylic acids. Chem. Commun (Camb). 2005 (43) 5438-5440. 

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