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Topic: Best route of lithiation  (Read 3323 times)

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Offline Cesium-137

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Best route of lithiation
« on: March 14, 2011, 09:36:36 PM »
Hi all,
I was looking for input on the best way to lithiate an alkyl halide. The problem is, the alkyl halide has a great LG on one end and the halide on the other, so once the halide is exchanged with lithium, intramolecular reactions can occur as well as polymerization. I've tried Li/X exchange with BuLi, but I am wondering if I could expect less side products and a cleaner reaction if I do a direct lithiation with 2eq Li metal. Any thoughts?
Thanks!

Offline Schrödinger

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Re: Best route of lithiation
« Reply #1 on: March 14, 2011, 10:56:00 PM »
Yes, I think adding 2 eq Li metal should do the trick. This is, after all, the first step in the famous Corey-House synthesis.

http://en.wikipedia.org/wiki/Corey-House_synthesis
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Offline Doc Oc

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Re: Best route of lithiation
« Reply #2 on: March 15, 2011, 08:47:25 AM »
I used tert-butyl lithium for this type of exchange and it worked fine.  It's a bit more on safety officers' radar these days, so that might be a headache.

Don't have any advice on how to avoid intramolecular reaction, that's not gonna be easy.

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