Sciencemadness Discussion Board

A question about a reaction involving translocation of carbonyl group of a ketone

Claus - 5-3-2014 at 04:43

The reaction is shown in the attached figure.
I got confused at the very first step...
(What is the function of C5H11ONO2?)

I guess the first step removes a hydogen at the alpha position and the second step is a reduction of a carbonyl group into a hydroxyl group.
Maybe the third step is related to a reaction of an epoxide.


rxn.png - 9kB

kmno4 - 5-3-2014 at 06:52

... and the rest is rather clear

mech.bmp - 177kB

Claus - 5-3-2014 at 08:00

Thank you for answering!
May I ask what happens next?

In the first step a β-nitro ketone forms
In the second step a β-nitro alcohol forms.(?)
In the third step a β-amino alcohol forms.(?)
Or could the third step be a Clemmensen reduction?

forgottenpassword - 5-3-2014 at 08:56

I don't agree that the first step will give a nitroalkane. There are examples of the following:
http://www.orgsyn.org/demo.aspx?prep=v90p0025
http://www.orgsyn.org/demo.aspx?prep=CV6P0840
The other steps, however, I am unsure of.

[Edited on 5-3-2014 by forgottenpassword]

Nicodem - 5-3-2014 at 09:34

Claus, this is no "translocation of carbonyl group of a ketone". The carbonyl group does not translocate. The first one is reduced and the final one is created. There is no rearrangement involved. Next time please do not ask such questions without citing the reference. Please read the forum guidelines for further information.
Quote: Originally posted by forgottenpassword  
I don't agree that the first step will give a nitroalkane. There are examples of the following:
http://www.orgsyn.org/demo.aspx?prep=v90p0025
http://www.orgsyn.org/demo.aspx?prep=CV6P0840
The other steps, however, I am unsure of.

Those are alpha-nitrosation of ketones, not alpha-nitration like in the discussed example.

The alpha-nitroketones can be reduced to the corresponding nitroolefins (see DOI: 10.1016/S0040-4039(00)86767-2) which can then be reduced further to the corresponding ketones:

ketone2isoketone.gif - 3kB

forgottenpassword - 5-3-2014 at 11:28

With the reagents specified I can only find examples of alpha nitroso compounds being produced. What reaction conditions are needed for alpha nitration of ketones with the same reagents?

Nicodem - 5-3-2014 at 12:34

Quote: Originally posted by forgottenpassword  
With the reagents specified I can only find examples of alpha nitroso compounds being produced. What reaction conditions are needed for alpha nitration of ketones with the same reagents?

For the nitrosations you need alkyl nitrites (usually in acidic media), while alkyl nitrates, like in this case, give nitroketones.

forgottenpassword - 5-3-2014 at 13:41

Oh yes, my mistake. I misread it as amyl nitrite.

kmno4 - 5-3-2014 at 14:29

Quote: Originally posted by Nicodem  
.... this is no "translocation of carbonyl group of a ketone". The carbonyl group does not translocate. The first one is reduced and the final one is created. There is no rearrangement involved. (...)

Yes, and no. Carbonyl groups do not jump from one place to another, but 'dissapearing' of one carbolyl group is very strictly connected with cration of another one.
There is an article titeled "Transposition of Ketones via 2-Nitro Ketones" (DOI: 10.1021/jo01269a007)
It gives full synthetic path from cholestan-3-one to cholestan-2-one exactly (almost) for conditions given in the post by Claus.
Maybe word "transposition" is more suitable than "translocation", but personally I see no difference (these words also function in my native language)

Nicodem - 6-3-2014 at 08:56

Quote: Originally posted by kmno4  
There is an article titeled "Transposition of Ketones via 2-Nitro Ketones" (DOI: 10.1021/jo01269a007)

It is an interesting synthetic strategy. I was not aware it was that well studied.
Quote:
Maybe word "transposition" is more suitable than "translocation", but personally I see no difference (these words also function in my native language)

I guess you are right about it. Both appear acceptable names for synthetic strategies, but not for reactions (it would imply some sort of a rearrangement).