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Topic: IChO problem: Small heterocycles  (Read 3041 times)

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Offline Rutherford

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IChO problem: Small heterocycles
« on: February 16, 2014, 08:06:32 AM »
I need to determine G. How will E react with 2TsCl? I thought the -OH hydrogen will be replaced by Ts, and the -NH, too. But what then? Will DMAP react?

Offline discodermolide

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Re: IChO problem: Small heterocycles
« Reply #1 on: February 16, 2014, 08:36:05 AM »
DMAP is a catalyst, forms an intermediate with the TsCl.
Both OH and NH are tosylated.
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Offline discodermolide

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Re: IChO problem: Small heterocycles
« Reply #2 on: February 16, 2014, 08:40:59 AM »
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Offline Rutherford

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Re: IChO problem: Small heterocycles
« Reply #3 on: February 16, 2014, 08:52:24 AM »
I can't solve it. What ester should be made?

Offline Rutherford

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Re: IChO problem: Small heterocycles
« Reply #4 on: February 16, 2014, 09:00:52 AM »
What is the reaction with phenol? Is it an electrophilic aromatic substitution in the para position of phenol, where the -OTs group will be replaced with phenol?

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Re: IChO problem: Small heterocycles
« Reply #5 on: February 16, 2014, 09:18:19 AM »
How about the phenol displacing the OTs to give an ether as the product?
O=S(N1C(C(F)(F)F)C1COC2=CC=CC=C2)(C3=CC=C(C)C=C3)=O
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Offline Rutherford

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Re: IChO problem: Small heterocycles
« Reply #6 on: February 16, 2014, 09:46:09 AM »
It is possible, too, but why would the ether be the main product?

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Re: IChO problem: Small heterocycles
« Reply #7 on: February 16, 2014, 09:53:13 AM »
Why not? It is simple alkylation of a phenol.
Please draw the product you think it is.
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Re: IChO problem: Small heterocycles
« Reply #8 on: February 16, 2014, 09:58:08 AM »
Just IMAGINE that instead of an OH you have a Br, how would phenol react with that?
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Offline Rutherford

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Re: IChO problem: Small heterocycles
« Reply #9 on: February 16, 2014, 09:58:35 AM »
Okay, the base will deprotonate phenol and activate it that way. That's what I oversaw. Thank you very much for the help. I really appreciate it.

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Re: IChO problem: Small heterocycles
« Reply #10 on: February 16, 2014, 10:12:22 AM »
No problem.
Note that very occasionally when I made a tosylate and tried to displace it with a nucleophile the reaction didn't work. What happened was that the chloride from triethylamine hydrochloride had already done the job. This happened only with certain compounds, but you should be aware that this side reaction can take place. I avoided this side reaction by using a different base.
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