[rcmishra]

Hello everybody,
recently I came across a patent where they have shown the conversion of primary amine to keto functionality using NBS and sodium methoxide.
Can anyone put some light on the mechanism of the same.
Thanks!
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RC Mishra

[Åke]

First of all, it is not possible to oxidize primary alcohols to ketones - they can only be oxidized to aldehydes and further to carboxylic acids. The use of NBS in an alcohol oxidation suggests that some kind of Corey-Kim oxidation¹ is employed, but I have never seen sodium methoxide being used as a base. What's the patent number?

1: http://en.wikipedia.org/wiki/Corey%E2%80%93Kim_oxidation

// Vedran

[Åke]

I now realise that I read your post wrongly - my bad. However, the oxidation of a primary amine to a ketone is also impossible.

// VH

[rcmishra]

No Probs...The patent No. WO2004/094371
However, we are predicting a mechanism via imine formation

I now realise that I read your post wrongly - my bad. However, the oxidation of a primary amine to a ketone is also impossible.

// VH

[Åke]

Thinking of primary alcohols made me mistake primary alkylamine with 1-alkylamine, sorry about that.  Yes, you are correct, it is possible and it has to proceed initially via imine. NBS first N-brominates the amine, sodium methoxide eliminates the HBr from the N-bromoamine to give imine, which in turn undergoes an acid catalyzed hydrolysis to give ketone. I once attempted NBS bromination of a secondary amine followed by HBr elimination using DBU as a hindered base but I never got the reaction to work.

Patent number: WO 2004094371

[OC pro]

Elimination of HBr leads to the imine which gets hydrolyzed to the ketone. Primary amines give aldehydes.

[Åke]

Primary amines give aldehydes.

Primary amines can give ketones too (as well as aldehydes). In fact, I think you are making the same mistake as I did.

[rcmishra]

Thanks Ake and OC Pro.
Your suggestions are towards our predicted mechanism, just now I found the original reference article from JACS.
The link to full text (for ACS subscribers) is http://pubs.acs.org/doi/pdf/10.1021/ja01034a027

Thanks again!
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