Ketocarboxylic acids cyclic

Thermolytic processes are so far known to play only a minor role in the generation of the PO ion. An isolated case is the thermolysis of the monosodium salt of acetonylphosphonic acid at 150 °C, which leads to acetone and sodium polymetaphosphate 107). A cyclic fragmentation mechanism, as known for P-ketocarboxylic acids, could lead to PO in this case. 

The butylated /J-ketoester C of Figure 13.26 is not the final synthetic target of the acetoacetic ester synthesis of methyl ketones. In that context, the /J-ketoester C is converted into the corresponding /J-ketocarhoxylic acid via acid-catalyzed hydrolysis (Figure 13.27 for the mechanism, see Figure 6.22). This /i-ketocarboxylic acid is then heated either in the same pot or after isolation to effect decarboxylation. The /f-ketocarboxylic acid decarboxylates via a cyclic six-membered transition state in which three valence electron pairs are shifted at the same time. The reaction product is an enol, which isomerizes immediately to a ketone (to phenyl methyl ketone in the specific example shown). 

Cyclic ketones also can be cleaved by oxidation with KMn04 (Figure 17.33). Under these conditions, 1, -ketocarboxylic acids or 1, -dicarboxylic acids are formed. The mechanism of this reaction is not known in detail. It is known only that KMn04 serves as a three-electron oxidizing reagent and that it is reduced to Mn02. 

Permanganate periodate Ketocarboxylic acids from cyclic a,) -ethyleneketones Steroids... 

Ketocarboxylic acids from cyclic glycols or a-hydroxyketones G... 

P-ketocarboxylic acid esters 43, 727 ketones, cyclic 44, 928 p-ketothiolic acid esters 43, 727 y-lactones 43,215... 

Ketocarboxylic acid esters from cyclic ketones s. 17, 194 Nitric acid... 

Cyclic ketocarboxylic acids from dicarboxylic acids... 

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... 

Ketocarboxylic acid esters from cyclic ketones... 

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