Carbonyl compounds vicinal diols, oxidative cleavage

The oxidative cleavage of the central carbon-carbon bond in a vicinal diol 1, by reaction with lead tetraacetate or periodic acid, yields two carbonyl compounds 2 and 3 as products. 

The oxidative cleavage of carbon-carbon bonds in vicinal diols [756, 759] is a reaction widely used in saccharide chemistry. Besides its application in this reaction, periodic acid achieves the oxidative coupling [757] or oxidation to quinones [758] of polynuclear aromatic hydrocarbons, the oxidation of methyl groups in aromatic compounds to carbonyl groups [760], the conversion of epoxides into dicarbonyl compounds [761], and the oxidative cleavage of trimethylsilyl ethers of acyloins to carboxylic acids [755]. 

The results of some oxidations with potassium permanganate differ depending on the pH of the reaction. For example, stearolic acid gives 9,10-diketostearic acid at pH 7-7.5 (achieved with carbon dioxide) and azelaic acid on treatment at pH 12 [864]. In some reactions, potassium permanganate is used as a catalyst for oxidation with other oxidants, such as sodium periodate. Thus alkenes are cleaved to carbonyl compounds or acids via vicinal diols obtained by hydroxylation with potassium permanganate, followed by cleavage by sodium periodate [763, 552]. 

While anodic oxidation of simple alcohols is of limited utility, direct oxidation of vicinal diols and related compounds is an excellent method for achieving oxidative cleavage to the corresponding carbonyl or carbonyl-acetal products, as in Eqs. (53) and (54). Unlike certain chemical glycol cleavage reactions, the anodic method is not limited by the stereochemistry of the substrate oxygens [132]. 

Because vicinal diols are obtained from alkenes, the combination of dihydroxylation followed by oxidative cleavage of a diol provides an alternative method to ozonolysis of alkenes to yield the same products. We can deduce the structure of the starting diol from the structures of the carbonyl compounds. 

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