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Topic: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed  (Read 5615 times)

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Offline wintermute

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decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« on: January 17, 2007, 10:13:43 AM »
hi all,

i am puzzled with this transformation. can anybody provide me with the hint, please?

thanks in advance
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Offline FeLiXe

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Re: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« Reply #1 on: January 17, 2007, 11:23:51 AM »
the start will probably be a deprotonation of the H that is alpha to three carbonyls because it is the most acidic one

Then you'll need a hydrogen shift and ethanol leaves (I guess)
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Offline movies

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Re: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« Reply #2 on: January 17, 2007, 12:40:49 PM »
Actually deprotonating the H between the three carbonyls won't get you anywhere (although you're right that it is the most acidic proton).  Think about using OH- as a nucleophile, or think about what else you have in solution that you could deprotonate.
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Offline FeLiXe

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Re: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« Reply #3 on: January 17, 2007, 06:26:50 PM »
having fun using the "socratic way" ?  :)

how about this: reverse Claisen-condensation  8)
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Offline movies

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Re: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« Reply #4 on: January 17, 2007, 07:53:33 PM »
Quote from: FeLiXe on January 17, 2007, 06:26:50 PM
how about this: reverse Claisen-condensation  8)

There you go.
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Offline wintermute

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Re: decarbonylation of alpha-acetyl-beta-ketoester - mechanism needed
« Reply #5 on: January 18, 2007, 06:28:32 AM »
uf, it was there. just to see it :(
now, everything makes sense. ammonia was used to avoid competing ester hydrolysis....
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