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Topic: Synthesis  (Read 4964 times)

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Offline John Mcmurry

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Synthesis
« on: August 14, 2018, 08:03:44 AM »
Hello!

Could anybody help me out finding the reagents for a succesful synthesis starting with cyclopent-4-ene-1,3-dione and ending with spiro[4.4]non-2-ene? I am totally lost on that one.

Thanks...

Offline clarkstill

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Re: Synthesis
« Reply #1 on: August 14, 2018, 08:31:07 AM »
It is a forum rule that you must at least show that you've attempted the problem.

Have you had any instruction on retrosynthesis?

Offline John Mcmurry

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Re: Synthesis
« Reply #2 on: August 14, 2018, 08:36:40 AM »
Nope...

Offline Babcock_Hall

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Re: Synthesis
« Reply #3 on: August 14, 2018, 09:02:34 AM »
Basically, it involves working backward from the product one step at a time.  Let's see what you can come up with...

Offline rolnor

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Re: Synthesis
« Reply #4 on: August 14, 2018, 09:43:55 AM »
The dione has very acidic hydrogens and would form a good nucleophile if base were added but it is also a excellent Michael-type alpha-beta unsaturated molecule and would probably polymerase very quickly under basic conditions, its a tricky startingmaterial.

Offline clarkstill

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Re: Synthesis
« Reply #5 on: August 14, 2018, 10:23:41 AM »
I would start by numbering atoms in the starting material and products, to identify where you need to make and break bonds.

Offline John Mcmurry

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Re: Synthesis
« Reply #6 on: August 14, 2018, 12:59:58 PM »
I can't find any mechanism that makes sense in this case

Offline John Mcmurry

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Re: Synthesis
« Reply #7 on: August 14, 2018, 01:03:12 PM »
I can't even find a way to remove the two C=O bonds. Maybe reduce them to C-OH, but what then?

Offline John Mcmurry

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Re: Synthesis
« Reply #8 on: August 14, 2018, 01:04:09 PM »
Reducing the C=O by grignard to C-OH

Offline wildfyr

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Re: Synthesis
« Reply #9 on: August 14, 2018, 01:11:31 PM »
There are many ways of reducing a ketone to an alkane. In fact if you type "ketone to alkane" into google the easiest way is the first result.

However, I suggest that this reduction not be your first step. You have a highly activated spot between the two carbonyls, what type of chemistry could you do there?

Offline John Mcmurry

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Re: Synthesis
« Reply #10 on: August 14, 2018, 01:26:22 PM »
Wolff-Kishner Reduction, my bad!

Between the two carbonyls, maybe NBS and hr, inserting an Br. Then making an diorganocopper reaction with my R'-Br and the cyclopentane-CuLi?

Offline John Mcmurry

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Re: Synthesis
« Reply #11 on: August 14, 2018, 01:28:11 PM »
Then I got this? Can I then reduce the two C=O with W-K reduction? and the synthesis is done

Offline John Mcmurry

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Re: Synthesis
« Reply #12 on: August 14, 2018, 01:52:06 PM »
Something like this?

Offline wildfyr

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Re: Synthesis
« Reply #13 on: August 14, 2018, 01:56:10 PM »
Very good, and very close. Take a look again at your cuprate. Its a bit off.

Offline John Mcmurry

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Re: Synthesis
« Reply #14 on: August 14, 2018, 01:58:00 PM »
But I just realized that I would end with this, right?

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