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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: azmanam on June 21, 2009, 11:26:00 PM

Title: Problem of the Week - 6/22/09
Post by: azmanam on June 21, 2009, 11:26:00 PM

The other question is still up if anyone wants to take a crack at part 2

http://www.chemicalforums.com/index.php?topic=33985.0

But we'll move on, since I think people are tired of that one :)

QUESTION: The following reaction is an example of an 'abnormal Michael addition.'  Provide a mechanism for this reaction that is consistent with the isotope labeling pattern shown.

Again, watch out for that ¹⁴C.  It'll throw you.

Title: Re: Problem of the Week - 6/22/09
Post by: orgopete on June 22, 2009, 11:59:04 PM

How about a Michael, intramolecular Claisen, and retro-Claisen?

Title: Re: Problem of the Week - 6/22/09
Post by: azmanam on June 24, 2009, 07:35:21 AM

yup, that'll do it.  Anyone want to draw up an arrow pushing mechanism?  The intermediate after the intramolecular Claisen is pretty neat looking.

Title: Re: Problem of the Week - 6/22/09
Post by: plankk on June 24, 2009, 10:04:46 AM

Neat looking? Maybe you have thought about such product

Title: Re: Problem of the Week - 6/22/09
Post by: azmanam on June 24, 2009, 10:16:10 AM

no... that's not what the product of the intramolecular Claisen looks like.  Try again.  The intramolecular Claisen may not be as straightforward as it first seems... :)

correction:That is the product of an intramolecular Claisen... just not one that gets to the product drawn.

Title: Re: Problem of the Week - 6/22/09
Post by: plankk on June 24, 2009, 11:47:01 AM

So maybe this is the interesting us product of the intramolecular Claisen.

Title: Re: Problem of the Week - 6/22/09
Post by: azmanam on June 24, 2009, 11:50:16 AM

yup