August 14, 2022, 06:46:14 PM
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Topic: Imine-Enamine Tautomerism  (Read 378 times)

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Offline racemiz.er

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Imine-Enamine Tautomerism
« on: August 02, 2022, 11:45:30 AM »
Okay, this is a tricky one... more of a thinker's question!

So, I was studying some imine formations. I was wondering if a tautomerism of imine is possible on the nitrogen end.



Any ideas guys?

Offline hollytara

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Re: Imine-Enamine Tautomerism
« Reply #1 on: August 02, 2022, 06:55:18 PM »
Yes - imines can easily tautomerize. 

But the one you show it is disfavored - double bond better next to aromatic ring and double bond better if NOT exocyclic to cyclohexane.

Often an amine / carbonyl is used that forms an exocyclic double bond so as to favor isomerization to the endocyclic, which then reacts predictably. 

Offline rolnor

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Re: Imine-Enamine Tautomerism
« Reply #2 on: August 03, 2022, 01:23:43 AM »
This is true for enamines, not imines. Enamines can form iminium salts. You need a secondary amine to get a enamine.

Offline racemiz.er

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Re: Imine-Enamine Tautomerism
« Reply #3 on: August 03, 2022, 02:24:33 AM »
Yes - imines can easily tautomerize. 

But the one you show it is disfavored - double bond better next to aromatic ring and double bond better if NOT exocyclic to cyclohexane.

Often an amine / carbonyl is used that forms an exocyclic double bond so as to favor isomerization to the endocyclic, which then reacts predictably.

Ummm... basically the cyclohexyl amine is a part of a cis isomeric cyclohexane ring. Do you have any suggestions for making it trans? Basically i am trying to invert cis 1,4 substituted cylohexane to trans 1,4 substituted cyclohexane

Offline rolnor

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Re: Imine-Enamine Tautomerism
« Reply #4 on: August 03, 2022, 05:16:30 PM »
You dont get the double bond on the cyclohexane, thats wrong. What substituents do you have on the ring? Its probably no problem to invert.

Offline racemiz.er

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Re: Imine-Enamine Tautomerism
« Reply #5 on: August 04, 2022, 01:20:17 AM »
You dont get the double bond on the cyclohexane, thats wrong. What substituents do you have on the ring? Its probably no problem to invert.

Hydroxy on para position. Unsure on how to invert. Is there a chemical process for inversion (not substitution)?

Offline kriggy

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Re: Imine-Enamine Tautomerism
« Reply #6 on: August 04, 2022, 02:55:29 AM »
Mitsunobu is usually used for this. react it with acetic acid and then hydrolyze the ester and you get inversion

Offline rolnor

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Re: Imine-Enamine Tautomerism
« Reply #7 on: August 04, 2022, 06:04:44 AM »
And that is substitution!

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