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Topic: [HELP ME]How does this reaction work?  (Read 4715 times)

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Offline snowman

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[HELP ME]How does this reaction work?
« on: September 04, 2007, 08:52:36 AM »
I want to promote this reaction.but i can not find a suitable base to deproton the desirede position.
please help me
thank you

Offline Custos

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Re: [HELP ME]How does this reaction work?
« Reply #1 on: September 04, 2007, 10:38:19 PM »
Your problem is not finding a suitable base for this reaction but that it will probably not go the way you want it to (product one). The benzylic proton will be deprotonated in preference to the one next to the nitrogen, and in addition the pyrrolidine position is more hindered for the incoming electrophile anyway.  I think you would more likely get product two. Even if you use two equivalents of a strong base (LDA) to try to form the di-anion the likely second point of allylation would be on the pyrrolidine ring but on the other side, away from the nitrogen.

Offline snowman

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Re: [HELP ME]How does this reaction work?
« Reply #2 on: September 05, 2007, 03:51:16 AM »
yes ,I think so ! :)
but my boss let me to choose a base system to accomplish this reaction.
and avoid the side product as low as possible. ???
he said that I could try to use Na+DMSO system ,t-BuOK+tBuOH,...
however I have not saw some literature containing this reagent.
I think I can do alkylation firstly,and then acylation. :)
can you give me some advice?   
thank you!

Offline Custos

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Re: [HELP ME]How does this reaction work?
« Reply #3 on: September 06, 2007, 08:09:34 PM »
Yes, you could possibly do the alkylation first, on 2-carbomethoxypyrrolodine, but you might need to protect the nitrogen otherwise you will get alkylation there. You could protect it with Boc perhaps.

As for the base, I would go for a stong base like LDA (lithium diisopropyl amide) to make sure. tBuOK in tBOH would probably be okay. Maybe an irreversible base like sodium hydride would be worth a shot as well.

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