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Topic: Why does this reaction not happening?  (Read 1802 times)

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Offline quishw

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Why does this reaction not happening?
« on: May 24, 2015, 03:47:19 PM »
Hi Guys,

I have a question from my own synthesis, where I wanted to oxidize the position α to the indole into a ketone. It should be quite an easy reaction normally done by DDQ, but here I can only pot a hydroxy group on that carbon but not a carbonyl. I also tried to oxidize it further with Dess-Martin and IBX and failed. I have been wondering why this reaction is not working, but I couldn't find a clue... However if I oxidize the molecule without the pyrrole part (see attachment), the reaction worked without any problem. Could anybody provide some idea why these happen? Thanks very much!

Offline TheUnassuming

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Re: Why does this reaction not happening?
« Reply #1 on: May 25, 2015, 02:41:08 PM »
What do you see when you push the oxidation?
When in doubt, avoid the Stille coupling.

Offline pgk

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Re: Why does this reaction not happening?
« Reply #2 on: May 26, 2015, 01:15:31 PM »
Consumption of DDQ for the formation of a π-complex with the alcoyl-pyrrole ring, might be possible. Try an assay by the double molar ratio of DDQ with a small amount of the compound. By the way, did you observe any unusual color formation during reaction (though, this not always a safe criterion of π-complex formation)?

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