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Topic: Acetal formation  (Read 4888 times)

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Offline vhpk

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Acetal formation
« on: April 07, 2010, 02:31:32 AM »
Hi everyone,
I've got a question related to the acetal formation.
I'm asked to draw the mechanism for this reaction:

I know how to draw the mechanism for an acetal formation. However, in this case, I don't know what to do with the double bond since the mechanism has nothing to do with the double bond. Why does it shift ? I also try the conjugation addition way but still get nothing positive.
Any help would be highly appreciated ;) Thank you :)
Genius is a long patience

Offline sHaY

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Re: Acetal formation
« Reply #1 on: April 07, 2010, 07:16:46 PM »
maybe it's some sort of a typo?

Offline orgopete

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Re: Acetal formation
« Reply #2 on: April 08, 2010, 01:15:24 AM »
I'm sure the structure is correct. Try drawing an acid catalyzed enolization reaction.
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Offline vhpk

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Re: Acetal formation
« Reply #3 on: April 08, 2010, 09:50:18 AM »
Thank you orgopete,
Here is my trial, is it correct ?

the next step is just acetal formation :D
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Offline orgopete

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Re: Acetal formation
« Reply #4 on: April 08, 2010, 11:36:31 AM »
That would do it (ignoring the error in 3 to 4). You could also start the ketalization at the protonated ketone (4). It might make some sense to understand the deconjugation process if protonation of 3 might be more favorable in the ketalization process than protonation of 1. 
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Offline vhpk

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Re: Acetal formation
« Reply #5 on: April 09, 2010, 04:28:44 AM »
Thanks a lot orgopete  ;D
Genius is a long patience

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