Keto Ketocarboxylic acid

Isatin is the inner anhydride (lactam) of a y-amino-a-ketocarboxylic acid, isatinic acid (A), and is converted into a salt of this acid by the action of alkali. The keto-group in position 3 can condense with many other substances, and for this reason isatin is manufactured on a technical scale and converted into valuable indigoid vat dyes. The magnificent thioindigo scarlet, which is obtained from isatin and a sulphur analogue of indoxyl (the so-called hydroxythionaphthene), may be taken as example qq... 

In aqueous-alcoholic sodium hydroxide, a-(l,2-dithiol-3-ylidene) /1-keto esters are hydrolyzed. The corresponding ketocarboxylic acid,... 

The use of the y-(trimethylsiloxy)nitrile derivatives (190) as a route to 1,4-bifunctional units is exemplified in a convenient synthesis of jasmonoid compounds. The addition of the Grignard reagent to the cyano group as the homologation step results in the keto alcohol (191) after subsequent hydration. The -y-ketocarboxylic acid (192) obtained from the... 

Ketene, 104, 232 Ketimines, 414 -Ketoacetals, 221 0-Keto allenes, 230, 231 a-Ketocarboxylic acids, 184 1 -Keto-7,7-dimethylnorcarane, 181 a-Keto esters, 237, 245 Ketones, 229, 274 Ketones, resolution, 58, 59... 

Keto-y-dicarboxylic acid esters from fi-ketocarboxylic acid esters s. 4, 770 ... 

The reaction of 10-undecenoic acid [2a], for example, with an acyl chloride such as acetyl chloride, heptanoyl chloride, hexadecanoyl chloride, and EtAlCl2 in a ratio of 1 1 2 in dichloromethane gave the corresponding P,y-unsaturated keto carboxylic acid [5a]-[5c] (Scheme 1) after a reaction time of 2 h at room temperature with high regioselectivity. The products were obtained as a mixture of ( /(Z)-stereoisomers ([( )] [(Z)] = 3 1) in isolated yields of 50-67%. Catalytic hydrogenation of the unsaturated ketocarboxylic acids [5a]-[5c] gave the saturated products in quantitative yields (2). 

Startg. m. heated at 150-160° with distillation of the product 3-methyl-2-butanone. Y 88%. - -Ketocarboxylic acid esters can be obtained by refluxing in benzene, e.g. ethyl 3-keto-4-hexenoate. Y 90%. F. e. s. J. Nokami, N. Kunieda, and M. Kinoshita, Tetrah. Let. 1975, 2841. 

The treatment of polyfunctional acids by alcohols in the presence of strong inorganic acids as catalysts can simultaneously be accompanied by the derivatization of other functional groups. For example, carbonyl groups in keto-carboxylic acids are converted into dialkylketal fragments in the presence of in ketocarboxylic acids. 

Isobutyric acid allowed to react at 0° with 2 equivalents Li-diisopropylamide in tetrahydrofuran, methyl pivalate added, stirred 0.5 hr., trimethylchlorosilane added, and stirring continued 0.5 hr. at room temp. -> trimethylsilyl y -keto ester (Y 70%) treated 0.5 hr. with methanol at room temp. -keto acid (Y ca. 100%) heated tert-hxiiyl isopropyl ketone (Y ca. 100%). - Highly subst. ketones can be prepared by this method. F. e., also synthesis of glutaric acids by Michael addition, s. Yu-Neng Kuo, J. A. Yahner, and C. Ainsworth, Am. Soc. 93, 6321 (1971) direct synthesis of -ketocarboxylic acids cf. B. Angelo, C. r. 276 (C), 293 (1973). 

Ketocarboxylic acid esters from -keto-/ -dicarboxylic acid esters... 

Recently, Groger et al. [51] developed a process for preparing (S)-tertiary leucine 22 by reacting the corresponding keto acid 23 with an ammonium ion donor in the presence of a whole cell of E. coli expressing amino acid dehydrogenase and cofactor-regenerating enzyme FDH. The substrate addition was metered such that the stationary concentration of 2-ketocarboxylic acid remains <500 mM and the external addition of cofactor, based on the total input of substrate, corresponds to <0.0001 equivalents. In this process, a reaction yield of 84% and ee of 99% were obtained for (S)-tertiary leucine at 130 g/1 substrate input. 

Ketones from y -ketocarboxylic acid esters with protection of the keto group as cyclic ketal Decarboxylation with cleavage of ketals... 

Use of RuOj/aq. Na(IO )/CCl to oxidise the secondary alcohol function in hydroxylactones gave ketolactones, while lactones gave ketocarboxylates [201-203], The former reaction is exemplified by 5-ejco-enrfo-dihydroxybicyclo[2.2.1] heptane-2-e (i(9carboxylic acid-y-lactone giving the 5-keto-6-endo product (Fig. 2.9). A number of other hydroxylactones were similarly oxidised, as were y- or 5-hydroxycarboxylates to ketocarboxylates [201]. 

We mentioned that by mixing vinyl epoxides and zerovalent palladium, the alcoholate formed was usually sufficiently basic to deprotonate the pronucleophile entity. In some cases, especially with ketones, low reactivity and yields were reported (Table To overcome the problem of the weak basicity of the alcoholate, silyl enol ethers, keto adds, or preformed lithium enolates have successfully been employed.f f" f f /3-Keto acids are masked enolates via the decarboxylation of the intermediary Tr-allylpalladium ]3-ketocarboxylate complexes. The main limitation of the use of keto adds as pronucleophiles seems to be their low reactivity toward the hindered cyclic vinyl epoxides. In these cases, the cationic n-allylpalladium complex undergoes ]S-elimination. Indeed, the reaction between benzoyl acetic acid and cyclobutadiene monoxide in the presence of Pd(PPh3>4 gives only the corresponding cyclopentanone and acetophenone as the... 

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