Rearrangement 3-ketocarboxylic acid

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... 

Photolysis of JV-aryl amides of /3-ketocarboxylic acids 135 proceeds in a different way.93 Thus, phenylisocyanate 136 is formed in 60% yield when in 135 R = phenyl. When R = methyl or propyl, the yield decreases to 18%. Consequently, this reaction belongs only formally to the scope of the discussed rearrangements. It seems that this is a special example of Norrish Type II reaction.324 This assumption is supported by the yield dependence of... 

Enollactones from ketocarboxylic acids s. 19, 328 also enolesters from ketones, and dienone-phenol rearrangement s. J. Org. Chem. 31, 324 (1966)... 

Titanium tetrachloride 3-Hydroxyethers from acetals by rearrangement s. 17, 790 o-Phenolketones from phenolesters Fries rearrangement s. 19, 798 Poly phosphoric acid Cyclic ketocarboxylic acids from dicarboxylic acid anhydrides s, 19,961... 

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