Lactones ketocarboxylic acids

Furthermore these reagents can attack ethers, double bonds and aromatic rings in more functionalized compounds. The nickel hydroxide electrode is a suitable reagent to overcome these difficulties The necessary alkaline electrolyte opens the lactone ring to the oxidizable hydroxycarboxylate. The nickel hydroxide electrode tolerates double bonds, ethers and aromatic rings and leads in good to excellent yields to ketocarboxylic acids (Eq. (6), Table 11). 

Table 11. Oxidation of lactones to ketocarboxylic acids at the nickel hydroxide electrode...

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. 

Under different reaction conditions, vicinal diol production [70] or C=C double bond oxidative cleavage to carboxylic acids occurs [59, 71], Dialdehydes are produced from cycloolefins, by tungstic acid as catalyst in t-butanol [72], Secondary alcohols yield ketones, while primary alcohols produce aldehydes or carboxylic acids [59, 68-69, 73-74], Different products are obtained from glycols, under different reaction conditions, 1,2-Diols are cleaved to ketocarboxylic acids and dicarboxylic acids [58, 75], or oxidised to a-hydroxy ketones [76], The latter can be obtained directly from the olefins, with lower selectivity [77], Lactones are formed by 1,4-diols and other a,o)-diols [78], Internal alkynes predominantly yield a,p-epoxyketones [79], or 1,2-diketones and carboxylic acids if HgfAcO) is added as the cocatalyst [80], Terminal alkynes yield a-ketoaldehydes and carboxylic acids. 

Sodium hydroxide 7-Ketocarboxylic acids ifpom, 7-dibromo-y -capboxycapboxylic acids a, -Ethylene-7-lactones fpom y, 7-dibpomocapboxylic acids 263. GOOH... 

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

Potassium tetrahydridoborate Lactones from ketocarboxylic acids... 

Hydroxycarboxylic aeids and lactones from ketocarboxylic acids Steric control... 

Nickellsodium hydroxide Lactones from ketocarboxylic acids s. 19, 81... 

Diisobutylaluminum hydride sulfuric acid Lactones from ketocarboxylic acids Stereospecific ring closure... 

Aluminum chloride s. under Li[AlHJ Microorganisms Optically active lactones from ketocarboxylic acids... 

Sulfuric acid/acetic anhydride a,j( -Ethylene- -lactones and lactones from 7-ketocarboxylic acids... 

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