3-oxocarboxylic acid esters

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... 

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 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. 

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)... 

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... 

ASYMMETRIC HYDROGENATION OF 2-OXOCARBOXYLIC ACID ESTERS AND UNSATURATED CARBOXYLIC ACIDS ON MODIFIED PT AND PD CATALYSTS... 

P-arylthio-y-oxocarboxylic acid esters 43, 486 -, 2-a-iodo- 44, 414 -, -, 2-vinyl-4-acyl- 43, 879 -, 2,5-dihydro- 44, 244... 

Pyrolysis of a-alkoxyenolesters Phthalides from o-oxocarboxylic acid esters... 

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. 

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. ... 

R = H or alkyl, the thiolate salts 27 are formed but no elimination takes place because of the low acidity of the hydrogen . Dialkylsulphide elimination from dialkylsulphonium methyl sulphates of -oxocarboxylic acids proceeds readily with aqueous alkali at 0 °C to furnish predominantly high yields of alkynoic esters (equation 86)" . Very recently intramolecular thiol eliminations (i.e. ring openings)... 

Diketones or P-oxocarboxylic add esters and amides react with amino add salts to yield the corresponding enamines 123 (Scheme 59).1 .729] jjjese derivatives are stable to basic reaction conditions and can be used for peptide couplings. Cleavage of the A/-vinyl derivatives is readily achieved with mild acids. The enamines are usually stabilized by an intramolecular hydrogen bond, as has been confirmed by NMR and IR spectroscopy.1 1... 

Amides and mono substituted amides of anthranilic acid react with y- or -oxocarboxylic acids to give the pyrrolo- or pyrido[l,2-a]quinazolines 76 ( = 0,Reactions were carried out under reflux in the presence of or without - p-toluenesulfonic acid. Instead of the carboxylic acids, the esters can be applied. 

The carbenoid reaction between alkyl diazoacetates and enol ethers, enol acetates and silyl enol ethers furnishes P-oxycyclopropane carboxylates (see Tables 2, 4, 5, 6, 7 and Scheme 5). The recently recognized synthetic versatility of these donor/acceptor-substituted cyclopropanes i 2,io3) (precursors of 1,4-dicarbonyl and P, 7-unsaturated carbonyl compounds, 4-oxocarboxylic acids and esters, among others) gave rise to the synthesis of a large number of such systems with a broad variation of substituents p-acetoxycyclopropanecarboxylates , p-alkoxy- or p-aryloxysubstituted cyclopropanecarboxylates 2-alkoxy-1-methyl-1-cy-... 

Konovalova, I.V, Burnaeva, L.A., Saifullina, N.S., and Pudovik, A.N., On the reaction of trimethyl silyl phosphite with esters and nitriles of a-oxocarboxylic acids, Zh. Obshch. Khim., 46, 18, 1976 J. Gen. Chem. USSR (Engl. Transl.), 46, 17-19, 1976. 

Because the target molecule has several more carbon atoms than the starting material, a Claisen condensation appears to be a good way to start this synthesis. The Claisen condensation forms a j8-keto ester that can be alkylated at the desired carbon because it is flanked by two carbonyl groups. Acid-catalyzed hydrolysis will form a 3-oxocarboxylic acid that will decarboxylate when heated. 

The next important finding was that the best catalyst is Raney Ni modified with tartaric acids (TA) rather than amino acids (AA) using the esters of 2-oxocarboxylic acid (mainly methyl acetoacetate, MAA) as model substrates. Using RNi-TA produced MHB with an ee above 50% from the hydrogenation of MAA in Ae liquid phase at higher temperatures, 50-70°C, and higher hydrogen pressure, 50-100 bar. 

There are many classes of substrate structures involved in heterogeneous enantioselective hydrogenation on modified metal catalysts. They consist of 2-oxocarboxylic acids and their esters, ketones, diketones, keto lactones, imsaturated acids, oximes, and amides. Enantioselectivities of heterogeneous chirally modified metal catalysts are determined in an important way by the matched interactions between die functional groups of the substrate and the modifier. 

For example, the Pt-alumina-alkaloid catalytic systems proved to be the best for enantioselective hydrogenations of 2-oxocarboxylic acids and their esters, especially the pyruvates (Blaser Baiker ), and the formates (Orito et al. ), originally studied in the "Orito Reaction" (see Bartok et... 

The gas-phase elimination kinetics of several ethyl esters of 2-oxocarboxylic acid have been found to be homogeneous, unimolecular, and follow a first-order rate law. ° Ethyl oxalyl chloride undergoes only decarboxylation, while both ethyl piperidinegly-oxilate and ethyl benzoyl formate exhibit parallel decarboxylation and decarbonylation reactions. The mechanisms of these decomposition reactions were described in terms of concerted discrete polar cyclic TS structures. 

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