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Topic: Johnson-Claisen rearrangement  (Read 1453 times)

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Offline AlphaScent

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Johnson-Claisen rearrangement
« on: October 25, 2012, 03:07:21 PM »
Would a terminal primary alcohol that is ω to a alcohol go through the johnson-claisen rearrangment if it is not protected?  I have done it with the THP group on there but is a pain to distill.  Would it work if I deprotected it first?  See attachment for structure.
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Offline discodermolide

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Re: Johnson-Claisen rearrangement
« Reply #1 on: October 25, 2012, 11:03:04 PM »
On the unprotected system the orthoacetate will react with both OH groups. But the rearrangement should only go with the allylic alcohol.
You may have to remove the orthoester at the primary end when you are done.
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Offline AlphaScent

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Re: Johnson-Claisen rearrangement
« Reply #2 on: October 26, 2012, 12:51:48 PM »
Thanks Disco,

I knew it would react to form an orthoester to sum degree, just didnt know to how much of a degree.  I am just doing my rearrangement on my crude material.  I have to hydrolyze the ester and remove the THP in the next two steps to afford the primary alcohol and carboxylic acid.  This should crystallize pretty easily I assume. 

Thanks again for the input  :D
If you're not part of the solution, then you're part of the precipitate

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