Ketocarboxylic acids derivatives

Use of a /3-ketocarboxylic acid derivative may circumvent this problem (8-ketocarboxylic acid derivatives react with esters of a-amino carboxylic acids to give (Y) a-aminonitriles afford (Z) in a condensation step. 

An ethereal soln. of the startg. enamine and triethylamine added at -20 to -10° to phosgene, the resulting triethylamine hydrochloride removed by filtration, and the filtrate treated dropwise at -20 to -10° with methanol and triethylamine methyl a-phenyl-/ -pyrrolidinoacrylate. Y 78%. - The reaction of enamines with phosgene occurs under mild conditions and provides reactive intermediates for the synthesis of / -ketocarboxylic acid derivs. and heterocyclics. F. e. and reactions s. A. Halleux and H. G. Viehe, Soc. (C) 1970, 881. 

Sulfuric acidHsopropenyl acetate Ketocarboxylic acid derivatives from ketocarboxylic acids... 

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 considerations that (Z), as a vinylogous amide, may undergo hydrolysis to (Y) whereas (Y) and (Z), being derivatives of /3-ketocarboxylic acids, can be subjected to acid cleavage suggest starting with (Z) itself as a general synthetic approach (Scheme 2). 

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... 

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). 

Figure 3.9 Typical capillary gas chromatogram of the derivatives of dicarboxylic acids (C2 Cg), ketocarboxylic acids ( C0C2, C0C4, pyruvic acid), and dicarbonyl (glyoxal) isolated from sea water (Sample collected in the Bay of Marseille (northwestern Mediterranean Sea) in September 2005. Reprinted with permission from Determination of low molecular weight dicarboxylic and ketocarboxylic acids in seawater sample) Tedetti, M, et ai, Analytical Chemistry (1 Sep 2006), 78 ( 7), 6012-6018. Copyright (2006) American Chemical Society).

Sometimes the products of carbonyl compounds silylation are not TMS-enols, but bis-TMS derivatives of hydrated carbonyls, RR C = 0 RR C(OH)2 RR C(OTMS)2. More unpredictable products can be formed during silylation of a-ketocarboxylic acids. For example, ketomalonic acid (II) besides the normal bis-JMS ester gives an unusual TMS derivative of the enol-hydrate form (see Fig. 7). 

Hoelderich, W. Laufer, M. C. Preparation of coumarin and derivatives from phenols and carboxyhc acids, P-ketocarboxylic acids, and derivatives in the presence of Nafion-silica composites, Deloxan, and/or narrow pore zeolites. PCT Int. Appl. WO 2004002980, 2004 Chem. Abstr. 2004,140, 77027. 

Applications. Acetylated cellulose powder is in principle suitable for separation of all lipophilic substances. Separation alone is not enough however the separated substances must be detectable. This fact has been responsible for the relatively modest extent of application of Ac-cellulose layers. They may be recommended for coloured substances and for those which are detectable in UV light. Some examples of use are separation of polynuclear aromatic compounds [31, 309, 357, 599, 600, 755], anthraquinone dyes [768], antioxidants [596], cutin acids [98], sweetening materials [595], rhodanine derivatives of acetoacetic acid and acetone in urine [574] and ketocarboxylic acids [575]. 

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