Sciencemadness Discussion Board

2-methyl, 3-indole acetic acid oxidation

Faust - 22-11-2013 at 03:42

Hi everyone,
I was wondering if there is appropiate way to oxidize the methyl in position 2 following by decarboxylation, without affecting acetic acid in position 3 of indole ring.

I was thinking about protecting acid with methyl ester but then, KMnO4 won't be suitable because acidic and alkaline medium will break the ester.

shall K2Cr2O7 be suitable ? or other route ?

Faust - 22-11-2013 at 15:40

Any suggestions ? :)

bfesser - 23-11-2013 at 16:34

Just one: don't post in all boldface.

Galinstan - 23-11-2013 at 16:51

Im no expert so correct me if im wrong but i don't think you can oxidise your methyl group to a carboxylic acid with kmno4 in this case. it would probably just destroy the ring, unless you have any evidence to support your suggested synthesis i don't think it can be done :)

Faust - 26-11-2013 at 09:49

Quote: Originally posted by bfesser  
Just one: don't post in all boldface.


Fair enough :)

Faust - 26-11-2013 at 10:00

Quote: Originally posted by Galinstan  
Im no expert so correct me if im wrong but i don't think you can oxidise your methyl group to a carboxylic acid with kmno4 in this case. it would probably just destroy the ring, unless you have any evidence to support your suggested synthesis i don't think it can be done :)


I don't think so, because it's possible to oxidize indole -2-methanol into indole -2- carboxaldehyde by Pot. permanganate in acetone, but no ring cleavage .

http://www.orgsyn.org/demo.aspx?prep=cv5p0567

thank you for sharing :)

zed - 26-11-2013 at 18:10

Indole Acidic Acid can be readily produced by a number of methods.

Producing it from 2-Methyl-Indole Acetic Acid, is unlikely.

It would be nice, since the route>Phenylhydrazine+Levulinic Acid>Phenylhydrazone. And, Phenylhydrazone +ZnCl+heat> 2-Methyl-Indole Acetic Acid. Easy and Inexpensive.

Alas, it is unlikely that you can oxidize the two position to a carboxyl.

If you have a pressure reactor, and Indole, synthesis is straightforward. Likewise, I have seen patents utilizing Ethyl-Acrylate, Acetic Anhydride, and heat. The 3 position of the Indole ring is remarkably easy to Alkylate. Though obtaining the Indole starting material may be a problem for some.

Not a problem if you have Phenylhydrazine however. You can make your own Indole.

Check the search engine. Check Organic Synthesis Online.

Oxidizing an alcohol to an aldehyde requires very mild conditions. Oxidizing a Methyl to a Carboxyl, is an entirely different animal. In general, once you get to oxidizing things, it's damned hard to stop the process.

You can try it, but there is a good chance you will end up with O-Nitro-Benzoic Acid, or some such thing.

[Edited on 27-11-2013 by zed]

[Edited on 27-11-2013 by zed]

[Edited on 27-11-2013 by zed]