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Topic: Retro-synthesis Problem!!! Cannot Figure Out!  (Read 10275 times)

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Offline Nikola95

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #15 on: February 02, 2014, 10:03:31 AM »

One more question: Dont you need to protect the other carbon in acetylene when doing the coupling reaction? So you dont get acetylene substitued on both carbons.


No, you don`t have to. As I have written, by using one equivalent of a base, acetylene can be gradually alkylated in the great yields. Look at my method.

Offline TheQuestion90

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #16 on: February 03, 2014, 08:59:44 PM »
Thank you all for your assistance I very much appreciate it!!!

Offline zsinger

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #17 on: February 04, 2014, 02:05:36 PM »
Giggity…..Suzuki Coupling…….Giggity…..:).  That is a reaction that should be mandatory in all organic classes, as it could have turned this problem into fewer steps!
            -Zack
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

Offline zsinger

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #18 on: February 04, 2014, 04:12:04 PM »
I am somewhat sure that this is not the 100% correct answer……while you are correct that stoichiometric amounts of base allow for coupling, unless there is only one side to pick from, we could end up with mixed products/not the products we want.  To me, it looks like a 50/50 shot of attack at the alkyne hydrogen.  Please do correct me if I'm wrong, which I frequently am! :)
          Cheers
               -Zack



One more question: Dont you need to protect the other carbon in acetylene when doing the coupling reaction? So you dont get acetylene substitued on both carbons.


No, you don`t have to. As I have written, by using one equivalent of a base, acetylene can be gradually alkylated in the great yields. Look at my method.
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

Offline zsinger

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #19 on: February 04, 2014, 04:17:51 PM »
Sorry last one…..Hunsdieker is messy and not a fun nor neat reaction, as you are dealing with elemental Bromine (you do not want to find out how toxic…..trust me).  Avoid at all costs.
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

Offline 408

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #20 on: February 04, 2014, 08:32:08 PM »
EtBr+Zn--> Butane
Butane-(radical halogenation& isomer separation)-->1-chloro butane (or start with methanol and do successive SOCl2, Mg, CH2O treatments till you get butanol and 1-chlorobutane lol)

BnOH-->BnCl
BnCl--(1.grig, 2. CH2O)-->Ph-CH2-CH2-OH--(SOCl2)-> Ph-CH2CH2-Cl

PhCH2CH2Cl--(Mg)-->PhCH2CH2MgCl--(Acetaldehyde)-->PhCH2CH2C(OH)CH3--(ox)-->PhCH2CH2C(O)CH3

BuCl-(Mg)->BuMgCl--(PhCH2CH2C(O)CH3)--> product.

But really, lots of different routes.  Above reactions are all just intro ochem to keep things simple.

Offline kriggy

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #21 on: February 05, 2014, 09:29:06 AM »
I am somewhat sure that this is not the 100% correct answer……while you are correct that stoichiometric amounts of base allow for coupling,
unless there is only one side to pick from, we could end up with mixed products/not the products we want.
 To me, it looks like a 50/50 shot of attack at the alkyne hydrogen.  Please do correct me if I'm wrong, which I frequently am! :)
          Cheers
               -Zack

Yes thast exactly what I was thinking. From my limited N-alkylation experience its exactly like that. Even with 1:1 ratio, we got mixture of mono, dialkylated (2 equivalent nitrogens)
and nonalkylated. Not to mention that they are pain to separate.
I guess its fine at paper but..

Offline orgopete

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Re: Retro-synthesis Problem!!! Cannot Figure Out!
« Reply #22 on: February 05, 2014, 10:42:19 AM »
This looks like an acetoacetate problem. Has this been taught yet? If so, I'd use it. If so, I think this could be a five or six step synthesis (depending on how you are counting).
[Edit, nope. I missed the requirement for two carbons or less for every step. It would be be longer than my earlier prediction.]
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