A-Ketocarboxylic acid chloride

Oxalyl chloride dimethyIformamide Carboxylic acid chlorides from carboxylic acid silyl esters a-Ketocarboxylic acid chlorides... 

Triethylamine 4(lH)-Pyridazones from a-ketocarboxylic acid chlorides and enamines... 

The reaction of iminium chlorides with diazonium salts occurs via addition to the diazo group. For example, reaction of an iminium chloride CLXXVII with p-nitrophenyldiazonium fiuoroborate yields the aryl-hydrazone of an a-ketocarboxylic acid amide CLXXVIII... 

Cobaltous chloride I sodium sulfide j calcium hydroxide jmethyl iodide a-Ketocarboxylic acids from halides Hal COCOOH... 

Scheme 9.131. A representation of the reaction between phenylethanoyl chloride (the acid chloride of phenylethanoic acid [phenylacetic acid, C6H5CH2CO2H]) and sodium cyanide to produce the corresponding a-ketonitrile which, on hydrolysis, forms the corresponding a-ketocarboxylic acid (in this case, phenylpyruvic acid).

Calcium carbonate a-Ketocarboxylic acid amides from isonitriles and carboxylic acid chlorides via a-ketiminochlorides... 

Benzo[f]quinoline synthesis with oxalyl chloride a-Ketocarboxylic acids from hydrocarbons Isocycles from ketones... 

Hydrogen chloride (s. a. under AlCl ) 3-Hydroxy- and 3-chloro-3H-indol-2-ones from a-ketocarboxylic acid anilides... 

A stirred soln. of the startg. phosphorane in methylene chloride treated por-tionwise with a soln. of 1.75 moles Pb-tetraacetate in the same solvent, and the product isolated after 0.5 hr. phenyl cyclobutylcarbonylthiolate. Y 59.1%. F. e., also a-ketocarboxylic acid esters from the analogous phosphoranes, s. E.Zbiral and E. Werner, M. 97, 1797 (1966). 

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... 

If, for example, an a-hydrogen is attached to the carbon atom of the iminium bond, transformation into the corresponding enamine (CXXV) occurs readily, which results in subsequent reaction of CXXV with the starting iminium chloride. Since attack on nitrogen is not possible self-condensation via attack on carbon has been observed, and jS-ketocarboxylic acid amides CXXVI are obtained in good yield... 

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). 

The acylation of oleic acid [la] with cyclopropanecarboxylic acid chloride gave in the presence of EtAlCl2 the corresponding branched P,y-unsaturated ketocarboxylic acid [7] (Scheme 2). Product [7] was obtained as a mixture of 9- and 10-re-gioisomers in a ratio of 1 1 as pure ( -adduct. 

The double unsaturated ketocarboxylic acid [10] was obtained by acylation of oleic acid [la] withcrotonic acid chloride (Scheme 4). Product [10], an allyl vinyl ketone, was formed as a mixture of flie 9- and 10-regioisomers (3). 

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