Syn- dihydroxylation and oxidative cleavage of 1,2-diols to form carbonyls

2J Syn- dihydroxylation and oxidative cleavage of 1,2-diols to form carbonyls 

The reaction of alkenes with potassium permanganate (KMn04) at low temperature, or osmium tetroxide (0s04), leads to the syn- addition of two OH groups (i.e. the two OH groups add to the same face of the double bond). 

The formation of the cyclic ester leads to the reduction of manganese, from Mn(VII) to Mn(V) 

2-Diols can be oxidised further to form carbonyl compounds. This results in the cleavage of the C-C bond. When potassium permanganate is reacted with alkenes at room temperature or above, the intermediate 1,2-diol can be further oxidised to form carboxylic acids. 

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