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Topic: Asymmetric Synthesis problems  (Read 3925 times)

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Offline greenday75

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Asymmetric Synthesis problems
« on: June 26, 2012, 11:03:25 PM »
Hey guys, im having some problems with an assignment on asymmetric synthesis. Any help would be greatly appreciated :)




Offline Doc Oc

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Re: Asymmetric Synthesis problems
« Reply #1 on: June 27, 2012, 01:20:37 AM »
You need to suggest some answers first, then we can guide you.

The way to start with these types of problems is to see which parts of the starting material seem to have tracked through to the product and figure out what reactions you know that can get you there.

For the 2nd question, look into Felkin-Ahn and Cram chelation, that ought to lead you home.

Offline PhDoc

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Re: Asymmetric Synthesis problems
« Reply #2 on: June 27, 2012, 01:35:04 AM »
Also, look into Zimmerman-Traxler transitions states for the Aldol reaction. That, in addition to the sterochemical analysis already suggested, should get you there.

The first problem is far more simple than you might imagine. Give it a shot!

If you want to really learn Organic Chemistry, you must be willing to struggle. A good fight is worth it in the end.
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Offline greenday75

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Re: Asymmetric Synthesis problems
« Reply #3 on: June 27, 2012, 01:38:01 AM »
thanks for your help. i just cant seem to grasp how the ring opens in question 2 and how the ether group on the right is formed. its hard for me write down my thoughts on paper because I have a broken arm at the moment, which is hindering my problem solving ability. thank you again for your input.

Offline Dan

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Re: Asymmetric Synthesis problems
« Reply #4 on: June 27, 2012, 03:05:29 AM »
i just cant seem to grasp how the ring opens in question 2 and how the ether group on the right is formed.

The functional group on the right is an ester (not an ether). You start with a lactone (a cyclic ester), and get an alcohol and an ester. One ester has been transformed into another ester...
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Offline greenday75

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Re: Asymmetric Synthesis problems
« Reply #5 on: June 27, 2012, 04:55:25 AM »
i just cant seem to grasp how the ring opens in question 2 and how the ether group on the right is formed.

The functional group on the right is an ester (not an ether). You start with a lactone (a cyclic ester), and get an alcohol and an ester. One ester has been transformed into another ester...

ahh, indeed you are correct. i blame my rookie errors on lack of sleep and too much coffee. thanks for your help :)

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