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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: Elan on December 10, 2013, 04:40:36 AM

Title: Tebbe alternative that doesn't react with esters?
Post by: Elan on December 10, 2013, 04:40:36 AM

I've been trying to convert a ketone to an alkene using Tebbe's reagent. Trouble is, there is a distant ester on the molecule that keeps getting converted as well. I've tried playing with the temperature many times over, but I just can't seem to get one reaction to happen without the other. Have any of you ever had a similar issue?

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: Archer on December 10, 2013, 04:49:04 AM

Quote from: Elan on December 10, 2013, 04:40:36 AM

I've been trying to convert a ketone to an alkene using Tebbe's reagent. Trouble is, there is a distant ester on the molecule that keeps getting converted as well. I've tried playing with the temperature many times over, but I just can't seem to get one reaction to happen without the other. Have any of you ever had a similar issue?

Unfortunately It's known for reacting with esters as well as ketones, have you considered protecting the ester as an orthoester?

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: Elan on December 10, 2013, 04:56:18 AM

Quote from: Archer on December 10, 2013, 04:49:04 AM

Unfortunately It's known for reacting with esters as well as ketones, have you considered protecting the ester as an orthoester?

That's a good idea, but it's an extra step that I'd like to avoid if I can...

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: Archer on December 10, 2013, 05:00:28 AM

Wittig reaction then? I am not sure how selective this is though.

 I don't recall the Wittig reaction converting esters.

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: discodermolide on December 10, 2013, 06:21:16 AM

I have had several of my esters undergo a Wittig! Methyl and ethyl.

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: Archer on December 10, 2013, 07:01:35 AM

Quote from: discodermolide on December 10, 2013, 06:21:16 AM

I have had several of my esters undergo a Wittig! Methyl and ethyl.

Oh, clearly I have never run these with esters present.

Title: Re: Tebbe alternative that doesn't react with esters?
Post by: discodermolide on December 10, 2013, 09:12:54 AM

Here is some literature for the Wittig with esters.
A. P. Uijtterwaal, F. L. Jonkers, A. van der Gen, J. Org. Chem., 1979, 44(18), 3157.
A. P. Uijtterwaal, F. L. Jonkers, A. van der Gen, J. Org. Chem., 1978, 43(17), 3306.
W. W. Epstein, L. A. Gaudioso, J. Org. Chem., 1982, 47, 175.