[Zainb]

The combination of potassium permanganate and active manganese dioxide (KMnO₄/MnO₂) produces a reagent that can be used effectively for the oxidation of alcohols to carbonyl compounds as shown below.





Any idea about the resulting reagent from this combination?

Usually KMnO₄ is used to oxidize alkenes.

Thanks for any help..

[discodermolide]

The combination of potassium permanganate and active manganese dioxide (KMnO₄/MnO₂) produces a reagent that can be used effectively for the oxidation of alcohols to carbonyl compounds as shown below.





Any idea about the resulting reagent from this combination?

Usually KMnO₄ is used to oxidize alkenes.

Thanks for any help..

I see you obtained this from the following paper. The title says it all!
I guess it is not a reagent but a supporting medium, similar to Pd/C.

[Zainb]

I have seen the complete paper,,, but they did not explain the mechanism...

They used 17.3 equivalents from MnO₂ and just 32 equivalents from KMnO₄,,, Then the permanganate just a catalyst,,, I try to use this regent on alkenyl compound but the reaction mechanism still unclear.

[orgopete]

I have not seen the paper. I don't know that the mechanism for KMnO4 oxidations of benzylic CH's has been proven, but it is generally believed to involve a radical reaction. From there, oxidation reactions generally involve
       H-C-O-X  H⁺ + C=O + X^-

where X is any group able to accept electrons, MnO_n, CrO_n, Br, Cl, Ag, etc.

Although the first step is usually carried out a elevated temperatures (to improve radical formation?), the reference reaction was carried out under mild conditions. If your substrate fails to react, I should presume the radical allylic oxidation step has a higher activation energy than is being supplied in this reaction. (If you have an alkene, I am surprised the hydroxylation reaction (similar to OsO₄ oxidation) is not occurring directly.)

[Zainb]

the hydroxy group is a good nucleophile, which will attack the metal atom centr in the MnO₂ (SN²) and  then one of oxynium atom of the intermediate, R₂-CH-O-MnO₂H, will depronate the proton in the cyclic transition state leading to the carbony compound