7-Ketocarboxylic - from

Cobaltous benzoate a-Ketocarboxylic from carboxylie acid esters s. lA, 219 (CeHfiOO) Co CH2COOR COCOOR... 

Silicon tetrachloride/aluminum chloride Ketocarboxylic from dicarboxylic acids s. 11,845... 

In another procedure, D-amino acid oxidase (52) is usehil to produce L-amino acids from DL-amino acids. a-Ketocarboxylic acids which are formed by the action of enzymes on D-amino acids, are aminated to form L-amino acids by coupling through the action of amino acid aminotransferases (53). 

Constitution of the Esters of the (3-Ketocarboxylic Acids and of the P-Diketones.—Ethyl acetoacetate is taken as example. It reacts like a ketone with phenylhydrazine, bisulphite, and other ketone reagents on the other hand it shows an acid reaction, it dissolves in alkalis, and gives the colour reaction with ferric chloride characteristic of ends and also of phenols. From this double behaviour it was formerly concluded that it was either purely ketonic or purely enolic and that the reactions in the other form were to be attributed to a rearrangement caused by the reagents used. The true state of affairs was first disclosed by... 

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... 

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. 

The UV spectrum [7max 214, 226 (sh), 247, 268, 308, 391, and 462 nm] of malasseziazole C (392) was similar to that of malasseziazole B (391), indicating the presence of a similar indolo[3,2- 7]carbazole framework. The H-NMR spectrum of malasseziazole C (392) was also very similar to that of malasseziazole B (391), except for the presence of a carboxylic group in place of an a-ketocarboxylic group. This was evident from its C-NMR spectrum, by the absence of an a-ketocarboxylic carbonyl carbon at 5 198.6, as well as a downfield shift ((5 126.5) of the carboxylic group attached to the C-6 carbon. The structure was also supported by the HMBC and HMQC correlations. Based on these spectral analyses and the structural similarity to malasseziazole B (391), the structure 392 was assigned to malasseziazole C (358) (Scheme 2.103). 

Variations of the synthesis of MOT derivatives from AT include the reactions of 3-ketocarboxylic esters with 1-formylaminoguanidine, which is an intermediate in the preparation of AT (82JAP57/175193), or with AT in situ (83JAP58/124787). 

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 add (192) obtained from the... 

Combining experiments and computations, Schreiner s research has always exhibited a symbiotic character. His research in carbenes exemplifies this interplay. Despite a great deal of previous work on carbenes, Schreiner discovered that the chalcogene carbenes were not well known. Knowing that the simplest example, hydroxymethylene, had not been made or characterized, he was sure that its preparation would be difficult. How does nature make carbenes he asked. The pyruvate cycle—CO2 extrusion from alpha-ketocarboxylic acids. She figured it all out So, the group tried oxalic acid and Bam Extrusion gave us dihydroxycarbene smoothly The surprise was it was so simple. But it was not all to be so simple. 

The dimerization of half esters to l,n-diesters is also called Brown-Walker electrolysis. Thereby valuable intermediates for the synthesis of medium-sized rings or l,n-difunctionalized compounds can be prepared (Table 2, entry 4). This reaction is also of industrial interest since in this way sebacic acid can be prepared from adipic acid half ester. This process has been scaled-up in Germany, the USSR and Japan, and yields as high as 93% have been reported. Reaction conditions and yields for the coupling of other half esters have also been studied in detail. 1, -Polyethylene- or polydifluoromethylene-dicar-boxylic acids are reported to be formed by electrolysis of azelaic acid or perfluoroglutaric acid. Ketocarboxylic acids can be coupled to 1,4-, 1,6- or 1,14-diketones (Table 2, entries 9 and 10). Aldehydes must be dimerized in the form of their acetals to obtain good yields, as has been shown for (17) and (18). The arrow on (10)-(18) indicates the location of dimerization, along with the yield and reaction conditions. 

Boehringer Ingelheim applied a chiral auxiliary for introduction of the trifluor-omethyl group in their synthesis of indole and azaindole trifluoropentanols (Figure 9.7). Under tetrabutylammonium fluoride catalysis the trifluoromethylation to the chiral a-ketocarboxylate ester results in a 84 16 diastereoselectivity. Further crystallization yields enantiopure material that is saponified to the acid under recovery of the chiral auxiliary. Transformation to the epoxide and construction of the azaindole from alkynyl pyridine [73] give access to the whole class of enantiopure pentanol indoles and azaindoles including BI 115. 

Of the five-membered heterocyclic ring derivatives, 0,0-diethyl-0-(3-methylpyrazolyl-5) phosphorothioate (51), introduced under the name Pyrazo-thion , is an insecticide with strong systemic action. The development of this compound was a further important result of the research program carried out by the research workers of the Geigy Co. on the phosphorus esters of enolisable heterocyclic compounds obtained from j -ketocarboxylic acid esters (Gysin and Margot, 1952). 

In gas-phase reactions zeolites are superior to non-zeolitic molecular sieves, metal phosphates, and metal oxides. Over the mildly acidic [B]-MFI (Si/B = 24) the synthesis of phenylpyruvic acid methyl ester yields up to 94 % at 200 °C and WHSV = 3 h 95 % product yield could be achieved with the cesium-doped material (0.6 % w w) [8]. With these concepts a-ketocarboxylic acid esters can be prepared from readily available feedstocks whereas conventional methods require the use of costly and environmentally problematical Grignard reactions. 

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