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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Olefination on October 24, 2012, 06:38:12 PM

Title: bromination/stereochemistry problem
Post by: Olefination 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!

Title: Re: bromination/stereochemistry problem
Post by: Olefination on October 24, 2012, 06:40:20 PM

Sorry, carboxylic acid group! You know what I mean.

Title: Re: bromination/stereochemistry problem
Post by: Olefination on October 24, 2012, 06:43:26 PM

Also I thought it might involve the carboxylic acid being deprotonated and becoming a lactone tether.

Title: Re: bromination/stereochemistry problem
Post by: Olefination 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.

Title: Re: bromination/stereochemistry problem
Post by: PhDoc on October 25, 2012, 01:43:58 AM

I think you're ready for that exam now!

Title: Re: bromination/stereochemistry problem
Post by: Olefination on October 25, 2012, 05:53:17 PM

Thanks, I hope so!