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Topic: A few steps organic synthesis  (Read 4557 times)

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Offline Rose-white

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A few steps organic synthesis
« on: January 01, 2012, 09:52:41 AM »
Hi everyone!

I was trying to solve this (below) in few steps, but I couldn't :( I tired Diels-Alder but I didn't get the product. I tired ozonolysis but don't know what should be next, and I was wondering, maybe something with lithum compounds?

What do You think?
« Last Edit: January 01, 2012, 10:12:20 AM by Rose-white »

Offline Rose-white

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Re: A few steps organic synthesis
« Reply #1 on: January 02, 2012, 11:06:31 AM »
Seriously, nobody?  :(

Offline fledarmus

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Re: A few steps organic synthesis
« Reply #2 on: January 02, 2012, 11:30:28 AM »
You're not showing much. What did you try? Diel's Alder looks like a reasonable start, if you choose the right diene...

Offline Rose-white

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Re: A few steps organic synthesis
« Reply #3 on: January 02, 2012, 11:50:06 AM »
I tried Diels-Alder, here's what I got:
So let's assume R1 is ester, so what should be as R2? maybe OH , if I use proton to enable water to leave, so there will be + on carbon, even the double bond move this position, the + still will be on the other carbon....

Offline Rose-white

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Re: A few steps organic synthesis
« Reply #4 on: January 02, 2012, 11:55:36 AM »
or I could use H2 so there is no double bond, and then Al2O3 to dehydrate , but the double bond will be in wrong place... (Zajcew rule)

Offline orgopete

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Re: A few steps organic synthesis
« Reply #5 on: January 02, 2012, 05:24:48 PM »
I don't foresee any simple transformation from cyclohexene to the indicated product. I also do not have context for this problem. I guess I missed this class. What chemistry was being discussed that led to this problem?
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Offline Rose-white

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Re: A few steps organic synthesis
« Reply #6 on: January 02, 2012, 05:57:04 PM »
this is whole context for this problem, it was given to me by teacher as a example of problem that can be on the exam, off course there won't be the same problem on exam and even similar, it's more about the level of difficulty, and other 4 examples I can solve, but this (and one more) I just can't. And the exam involve organic chemistry in general.

Offline fledarmus

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Re: A few steps organic synthesis
« Reply #7 on: January 02, 2012, 08:09:27 PM »
What if the Diels Alder reaction is the last step in the synthesis? Barring possible functional group conversions of course...

Offline CaverKat

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Re: A few steps organic synthesis
« Reply #8 on: January 02, 2012, 09:00:57 PM »
This would probably not work at all,  but I was thinking something along the lines of adding these two:


Offline Yakimikku

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Re: A few steps organic synthesis
« Reply #9 on: January 02, 2012, 09:22:07 PM »
What if the Diels Alder reaction is the last step in the synthesis? Barring possible functional group conversions of course...


I was going to give the same hint! Try doing a retrosynthesis with Diels Alder as the last step.

Looks like to me it's 5 steps. What o-chem class are you in? I had to cheat. There's a useful reagent I didn't know about, but what can I say, I'm not an organic chemist.

Another hint--something else you suggested might be a good starting point.. ;)

Offline orgopete

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Re: A few steps organic synthesis
« Reply #10 on: January 03, 2012, 03:05:57 PM »
Okay. I concede that I never asked students for problems of this difficulty without giving them some kind of examples or guidance as to how they might do this. Since it does look like a Diels-Alder product, this is the kind of reactions that one might try, sans reagents and any selective protection-deprotection schemes that might be needed or other product that might have been isolated from the oxidation.
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Offline Yakimikku

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Re: A few steps organic synthesis
« Reply #11 on: January 03, 2012, 03:14:37 PM »
Okay. I concede that I never asked students for problems of this difficulty without giving them some kind of examples or guidance as to how they might do this. Since it does look like a Diels-Alder product, this is the kind of reactions that one might try, sans reagents and any selective protection-deprotection schemes that might be needed or other product that might have been isolated from the oxidation.

You got it! Minus an important protection/deprotection. For those curious, you can attribute the synthesis to E.J. Corey's lab:

Org. Lett., 2003, 5 (21), pp 3979–3982 (http://pubs.acs.org/doi/abs/10.1021/ol035542a)

Offline Rose-white

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Re: A few steps organic synthesis
« Reply #12 on: January 03, 2012, 05:24:16 PM »
hey, today I asked my teacher to help me with this and he clued me in on that synthesis. I had tired many ways but by myself I would never solve this. So thank you all, who was trying solve this or even wondering how to solve it, and thank you, orgopete  ;)

I need to think better and study better.

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