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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: TwistedConf on October 21, 2014, 03:27:23 PM

Title: Alcohol to Ketone in the Presence of an Unprotected Amine
Post by: TwistedConf on October 21, 2014, 03:27:23 PM

I need to oxidize a secondary alcohol to ketone in the presence of an unprotected secondary aromatic (aniline-type:  benzene-NH-R).  These are not common in the literature.

Dess-Martin or methods that use acidic conditions so that the amine is "protected" by protonation come to mind.

Anyone have any suggestions before I start the trials?

Title: Re: Alcohol to Ketone in the Presence of an Unprotected Amine
Post by: discodermolide on October 21, 2014, 07:56:13 PM

I appreciate the protonation route as a means of amine protection, but do you trust the amine to remain protonated throughout the entire oxidation reaction and work-up?
I don't, but then I have no idea what you will be using for the oxidation.

Better to put a Boc on that nitrogen, oxidise and remove the Boc with acid to give the amine salt.

Title: Re: Alcohol to Ketone in the Presence of an Unprotected Amine
Post by: C-hemCards on October 21, 2014, 09:44:35 PM

Discodermolide makes a valid point. That being said, I'd give it a go with Dess-Martin. I think that will probably work unless the secondary alcohol is horrendously hindered.

Another option is to add an equivalent of AcOH to the rxn mixture before the oxidation.

Title: Re: Alcohol to Ketone in the Presence of an Unprotected Amine
Post by: Dan on October 22, 2014, 03:22:56 AM

Maybe TFAA/DMSO? This should temporarily protect the aniline as the TFA amide, which should hydrolyse easily with a basic workup.