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Topic: Can someone explain this problem to me?  (Read 2326 times)

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Offline MechRocket

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Can someone explain this problem to me?
« on: April 03, 2010, 10:53:35 PM »




Can someone lead me through how to do this problem step-by-step?

Here's what I did:

Lithium organocuprates add only through 1,4 addition so I made the methyl anion attack the beta carbon on the left. This would shift the electrons to form a double bond between the carbonyl carbon and the alpha carbon. Also, the double bond between the C and the O would shift to be on the O. Next, I had the double bond between the carbonyl carbon and the alpha carbon grab a proton from the H3O+, which made my final product.

However, I don't know how that double bond on the right shifted over to form a conjugated product.

Any help is appreciated, thanks.

Offline cananian

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Re: Can someone explain this problem to me?
« Reply #1 on: April 04, 2010, 12:44:31 AM »


after nucleophilic addition at Beta carbon and the protonation of alpha carbon, a base in the media will abstract the highly acidic allylic proton at alpha (on right side) forming a very stable carbanion due to resonance with double bond and the carbonyl, once it is resonated with the double bond an alpha-beta unsat system is formed as well as a carbanion on the terminal carbon on right side that is protonated later and giving the product you need

Offline MechRocket

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Re: Can someone explain this problem to me?
« Reply #2 on: April 04, 2010, 02:11:04 AM »
thanks for the response, that makes sense.

however, what will be the base that extracts the allylic Hydrogen? and does this occur after step 2 (adding H3O+)?

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