Dihydroxylation of Alkenes
Cis-dihydroxylation of Alkenes: Reaction with Permanganate
In the first step, permanganate anion is added to the olefin with formation of a cyclic manganese ester.
The cyclic intermediate is being hydrolyzed to the cis 1,2-diol. The formed manganese(V) compound disproportionates to MnO2 and MnO4 -
Potassium permanganate is a strong oxidizing agent that can oxidize the diols further resulting in the formation of diketones and dicarboxylic acids, the latter by cleavage of the original double bond. Therefore, the yields of 1,2-diol are rarely above 60 %.