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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: Doc Oc on January 30, 2013, 02:45:50 PM

Title: Alkylation vs acyl substitution of amide
Post by: Doc Oc on January 30, 2013, 02:45:50 PM

I'm having a strange problem.  I have a linear amide with a primary alkyl bromide.  I am attempting to phenoxylate the compound, but instead I am seeing substitution at the amide and preservation of the bromine!  I've used several different solvent/base combos (DMF, DCM, acetone, Et₃N, K₂CO₃, pyridine, proton sponge) with cooling/heating/neither, none of them giving a different result.  I can't say I've ever seen this happen and I'm rather surprised.  Does anybody have any suggestions on how to solve this?  I'm about at my wit's end.

Title: Re: Alkylation vs acyl substitution of amide
Post by: Dan on January 31, 2013, 03:05:03 AM

That's pretty fruity. What's the amide, something active like an acyl pyrrole?

Not the cheapest solution, but maybe try silver phenoxide - the Ag⁺ should strongly activate the alkyl bromide.

You could also bulk up the amide.

Title: Re: Alkylation vs acyl substitution of amide
Post by: Doc Oc on January 31, 2013, 07:56:18 AM

Morpholine!  I like your suggestion and I should have thought of it since I've used silver salts in challenging alkylations in the recent past.  Thanks for the refresher Dan.