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Topic: bromination/stereochemistry problem  (Read 1739 times)

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Offline Olefination

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bromination/stereochemistry problem
« on: October 24, 2012, 06:38:12 PM »
Hello, I'm working on a practice exam (the real exam is on Friday) and I'm stumped on a problem:

"Show the product from the following reaction, and draw the reaction mechanism."
The reaction has this cyclohexene with a carbonyl group whose bond is coming up out of the paper. There is a bromine addition, and weak base in water. See attached image.

I thought it may have something to do with a stereoselective or stereospecific bromination, or maybe a bromolactonization, but I'm not sure.
(Sorry about the funky formatting-- my ChemBioDraw subscription expired so I used Photoshop to make the picture, and I don't know how to do subscripts in Photoshop because I'm computronically challenged).
Thank you!

Offline Olefination

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Re: bromination/stereochemistry problem
« Reply #1 on: October 24, 2012, 06:40:20 PM »
Sorry, carboxylic acid group! You know what I mean.

Offline Olefination

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Re: bromination/stereochemistry problem
« Reply #2 on: October 24, 2012, 06:43:26 PM »
Also I thought it might involve the carboxylic acid being deprotonated and becoming a lactone tether.

Offline Olefination

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Re: bromination/stereochemistry problem
« Reply #3 on: October 24, 2012, 06:54:43 PM »
Actually I think I figured it out... bromolactonization, then deprotonation of the COOH group, which then attacks the alkene and forms a lactone tether. The Br is on the bottom face and the lactone tether on the top.

Offline PhDoc

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Re: bromination/stereochemistry problem
« Reply #4 on: October 25, 2012, 01:43:58 AM »
I think you're ready for that exam now!
O-Chem Prof

Offline Olefination

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Re: bromination/stereochemistry problem
« Reply #5 on: October 25, 2012, 05:53:17 PM »
Thanks, I hope so!

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