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Topic: Retrosynthesis analysis - open if you dare!  (Read 5083 times)

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Offline asdaf7477

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Retrosynthesis analysis - open if you dare!
« on: April 09, 2010, 05:50:16 PM »
Dear Chemists,

I have been scratching my brain at this problem, would anyone kindly help with the retrosynthetic analysis as well as the forward enantioselective synthesis of a molecule. I can't upload the Chemdraw version of it, and I can't fin the molecule on-line, here is one close enough to it, change the subtituents to the ones below:

http://www.bmrb.wisc.edu/metabolomics/standards/D_glucono_1_5_lactone/lit/3498.png

Note that the Carbonyl is referred to as at position 1, the oxygen in the ring is at position 2 and so on clockwise.
redraw the molecule so that the following is the structure:
- At position3, a backward facing CH2)OH group as well as a forward facing H
- At position 4 and 5 2H on each cabon
- At position 6 there are two groups, one is a forward facing Methyl group, and the second is a backward facing CH2Ph group.

Sorry if this is a little confusing, my Chemsketch isn't uploading for some reason. I will try again tonight, if it work I will re-post this

Thank you for reading!


Offline zengjia1029

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Re: Retrosynthesis analysis - open if you dare!
« Reply #1 on: April 09, 2010, 06:03:19 PM »
As you defined, the structure must be as below:

Offline asdaf7477

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Re: Retrosynthesis analysis - open if you dare!
« Reply #2 on: April 09, 2010, 06:09:42 PM »
yes thank you!!!

Offline zengjia1029

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Re: Retrosynthesis analysis - open if you dare!
« Reply #3 on: April 09, 2010, 06:29:24 PM »
My synthesis route. Any comments, thanks in advance.

Offline asdaf7477

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Re: Retrosynthesis analysis - open if you dare!
« Reply #4 on: April 09, 2010, 06:38:37 PM »
wow thank you so much! I will need some time to absorb this in, if i have any questions i'll let you know :)

Offline StarvinMarvin

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Re: Retrosynthesis analysis - open if you dare!
« Reply #5 on: April 09, 2010, 07:21:25 PM »
Just by quickly looking at the scheme:

first reaction needs Cu to facilitate 1,4 addition, doesn't it?

« Last Edit: April 09, 2010, 07:52:25 PM by StarvinMarvin »

Offline zengjia1029

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Re: Retrosynthesis analysis - open if you dare!
« Reply #6 on: April 09, 2010, 10:58:29 PM »
Just by quickly looking at the scheme:

first reaction needs Cu to facilitate 1,4 addition, doesn't it?


You are right! I have made a mistake. bisallyl copper lithium always go through a 1,4 addition.

Offline mirro

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Re: Retrosynthesis analysis - open if you dare!
« Reply #7 on: April 10, 2010, 10:18:53 AM »
In step 2 of your Evans aldol reaction, i think you need to add a base like DIPEA to form the enolate, and I wonder if it works stereoselective with an electrophile like BnBr.

I think the product of your last reaction will be this:

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