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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Acadasol on January 17, 2015, 01:19:01 PM

Title: Elimination reaction with potassium tert butoxide.
Post by: Acadasol on January 17, 2015, 01:19:01 PM
Does anyone knows how else I can better eliminate a vicinal bromide to give an alkyne product without the tert butyl group substituting the methoxyl group in a linker attached to the cyclic vicinal bromide.
Title: Re: Elimination reaction with potassium tert butoxide.
Post by: kriggy on January 17, 2015, 01:33:56 PM
I know its not the answer you wanted but why not eliminate 1st and then do the acylation of nitrogen? I cant think of way of doing that without something happening to that ester bond. Maybe using non-nucoleophilic base?
Title: Re: Elimination reaction with potassium tert butoxide.
Post by: Acadasol on January 17, 2015, 09:20:57 PM
I know its not the answer you wanted but why not eliminate 1st and then do the acylation of nitrogen? I cant think of way of doing that without something happening to that ester bond. Maybe using non-nucoleophilic base?

That sounds good but the nucleophilic nitrogen will cyclize if it were without the acyl group. The cyclization has been reported already.
Title: Re: Elimination reaction with potassium tert butoxide.
Post by: critzz on January 17, 2015, 09:31:20 PM
Have you already tried running the reaction? As long as there is no water present or tBuOH as solvent I don't really think it's a problem?
If it does happen try running the reaction at lower temperatures.
Title: Re: Elimination reaction with potassium tert butoxide.
Post by: Acadasol on January 17, 2015, 10:18:00 PM
Have you already tried running the reaction? As long as there is no water present or tBuOH as solvent I don't really think it's a problem?
If it does happen try running the reaction at lower temperatures.

I actually maintained the reaction at -40 degree Celcius and moisture free to the best of my knowledge. Do you think bringing the temperature further down is going to help? Thanks!
Title: Re: Elimination reaction with potassium tert butoxide.
Post by: k1mng on January 20, 2015, 09:30:41 PM
Hey Acadasol, in case cooling it further doesn't work, perhaps you could try sodium methoxide? If you have a bit of dry methanol and some sodium you can do the elimination. Of course, lower temps should help to avoid cleaving that amide.