yumi43

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Jan 23, 2004
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i understand this is a wittig reaction, but how does the last step after the ylide formation result in the product given? thanks :)
 
May 22, 2009
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I don't have the question on me but in a wittig reaction, all you have to remember is that the Carbon (along with whatever is attached to that carbon, and without any change in configuraiton) attached to the phosphorous in ylide will replace the oxygen of the carbonyl group, forming a C=C double bond.
There reaction goes through a intermediate (or maybe just a transition step i dont remember) that has a square of 4 bonds with (P-C-C-O-P(back to start)) as its 4 sides.
 
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yumi43

yumi43

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oh thanks for your reply! but i was actually asking about the part that happens right after the wittig reaction in this particular problem. i guess it's too hard to explain what it is without having the problem in front of you.
 
May 22, 2009
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oh thanks for your reply! but i was actually asking about the part that happens right after the wittig reaction in this particular problem. i guess it's too hard to explain what it is without having the problem in front of you.
I do have the problem now. Are you talking about the last step where the Ylide with acetone gives product B? That IS the wittig reaction, not the formation of the Ylide. And if you just replace the O in acetone by the second carbon in the butane attached to ylide, you will get product B. Right?