P-Ketocarboxylic acids

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. 

Their structures were mainly determined by spectral studies using EI-MS, IR, H-NMR, NOE, and CD spectra (75). They consist of a main spiroether moiety, corresponding to 1-oxaspiro[5. 5]undec-4-ene-8-one ring system, (including seven asymmetric centers and possessing a (Z)-olefin, a mefa-substituted phenol, and a P-ketocarboxylic acid functions) and a P-hydroxy-y-lactone moiety. Oscillatoxin Ds are present as esters of both moieties. On the other hand, aplysiatoxins are present as macro bis-lactones including a spiroacetal. We are interested in the relationship between oscillatoxins and aplysiatoxins from a biosynthetic point of view. 

Hirai, Y., Aida. T, Inoue, S. (1989). Artificial photosynthesis of P-ketocarboxylic acids from carbon dioxide and ketones via enolate complexes of aluminium porphyrin, J. Am. Chem. Soc., Ill 3062. 

Figure 1 shows the infrared spectra of the p-ketocarboxylic acid-functionalized poly (IB-PMS) copolymer (middle spectrum) and the ester-functionalized poly (IB-PMS) copolymer (top spectrum). The infrared spectrum of the ester product shows the disappearance of a broad peak at 3500-3100 cm" 1 due to the carboxylic add group and the appearance of new characteristic ester peaks at 1738 cm" and 1718 cm", in addition to the carbonyl peak at 1610 cm"l (Figure 1). This suggests complete conversion of the acid-fiinctionalized polymer to the ester-frmctionaliz(Kl polymer.

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

P-ketocarboxylic acid esters, asym. acylation 44, 734 -, chir ... 

Acylketeneacetals a- and P-Alkoxyenolesters 1-Alkoxy vinylesters 15 Enol carbonates Glycidic acid esters P-Ketocarboxylic acid esters Acylacetic esters 5... 

Carboxylic acid esters from l,3-dioxane-4,6-diones p-Ketocarboxylic acid esters... 

Potassium carbonate (s.a. under Pt(CO)2(PPh )2) a-Bis(alkylthio)methylene-P-ketocarboxylic acid esters s. 44, 46... 

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