September 15, 2019, 06:42:55 AM
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Topic: Grignard Addition to Propylene Oxide  (Read 268 times)

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Offline AlphaScent

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Grignard Addition to Propylene Oxide
« on: July 09, 2019, 03:57:43 PM »
Hey All,

Does anyone have any experience with adding Grignards to propylene oxide in good yields?  It seems a lot of the older literature shows that the alcohol is made as a minor product to the bromohydrin.  Also there is possible polymerization that can occur.  Adding dioxane I think may help with producing the dialkyl Mg species and pushing the Schlenk equilibrium to the right. This all may be a decent idea but let me know if you have any practical experience doing this type of work. 

A reaction would be like 1-octylMgBr reacting with propylene oxide.

Thank you in advance!

Cheer!
If you're not part of the solution, then you're part of the precipitate

Offline rolnor

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Re: Grignard Addition to Propylene Oxide
« Reply #1 on: July 09, 2019, 04:29:34 PM »
Best to make the dialkyl magnesium cuprate and make BF3-complex, then mix with the epoxide. I think its simmilar to dialkyl lithium cuprates. I have reacted grignard with secondary epoxide with good yield so I am not sure if cuprate is neccesary. HMPA would probably speeed things up. In your case the epoxide is not sterically hindered so maybe its very easy.

Offline pgk

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Re: Grignard Addition to Propylene Oxide
« Reply #2 on: July 10, 2019, 08:40:45 AM »
Addition of Grignard reagents to ethylene oxide, is described in various editions of the Vogel’s Textbook of Practical Organic Chemistry (Chapter: Aliphatic alcohols). For example, in the 5th Edition, this corresponds to the pages 535-537. However, the obtained yields are rather moderate (50-70%). 
Anyway and in the case of propylene oxide, you will get a mixture of alcohols and the secondary alcohol will probably be the major product.
« Last Edit: July 10, 2019, 08:53:22 AM by pgk »

Offline rolnor

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Re: Grignard Addition to Propylene Oxide
« Reply #3 on: July 10, 2019, 10:50:11 AM »
Here is the reaction I made, dont remember the yield:

https://pubs.acs.org/doi/10.1021/jo00009a012

Offline AlphaScent

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Re: Grignard Addition to Propylene Oxide
« Reply #4 on: July 12, 2019, 03:32:23 PM »
rolnor,

You saw no Payne rearrangement?

I have a reference that adds an aliphatic Grignard to propylene oxide utilizing catalytic CuI.  They do report minor Wurtz products which is kind of annoying.  I am going to try it because it is an easy reaction. 

We shall see.

Cheers!

If you're not part of the solution, then you're part of the precipitate

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