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Author Topic: Grignard Reagents?  (Read 2225 times)

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ILoveISO

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Grignard Reagents?
« on: March 04, 2011, 11:23:10 AM »

How would this work?

BrMgCH2CH2CH2CH2MgBr, THF

------------------------>
H, H2O

How does a grignard reaction work when there is two BrMg's present? The compound I start with is a 5 membered ring with a O at one of the points, carbonyl oxygen, and 2 methyl groups  at two different carbon corners.

Anyone got any idea? Thanks
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ILoveISO

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Re: Grignard Reagents?
« Reply #1 on: March 04, 2011, 01:07:31 PM »

Also once the grignard opens up this lactone, how does the ring reform cause that is what the product ends up to be so I assume it had to have opened up then reformed...
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Dan

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Re: Grignard Reagents?
« Reply #2 on: March 05, 2011, 02:12:09 PM »

Draw or explain properly. Preferably both.
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ILoveISO

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Re: Grignard Reagents?
« Reply #3 on: March 05, 2011, 04:08:23 PM »

Okay basically it is a Lactone with 2 methyl groups at the top right and bottom left of the ring. (This is a 5 membered ring) Now it undergoes this reaction

BrMgCH2CH2CH2CH2MgBr, THF
----------------------------->
H+, H2O

My question is how does a grignard reagent work when there is TWO MgBr's in there? Where does it attack? The lactone will break apart but how will the ring reform?
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Dan

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Re: Grignard Reagents?
« Reply #4 on: March 06, 2011, 12:02:53 AM »

Okay basically it is a Lactone with 2 methyl groups at the top right and bottom left of the ring. (This is a 5 membered ring)

This is exactly why we have nomenclature. Do you mean 3,5-dimethyldihydrofuran-2(3H)-one?

Quote
The lactone will break apart but how will the ring reform?

Have you been given the product's structure? What makes you think the "the ring" will reform?

Here's a question for you - if you treat ethyl acetate with two equivalents of MeMgBr, what do you get?
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