[taurean]

Guyz,

Any suggestions on how to carry out a Michael rxn of a carbon nucleophile (eg: malonates, cyano acetate, etc.) with acrylic acid?

I cannot use the derivative of acrylic acid.

Any help is greatly appreciated!

[orgopete]

Although I am not really an expert in Michael additions to acrylates, would you care to show or explain why an acrylate ester cannot be used?

[taurean]

Although I am not really an expert in Michael additions to acrylates, would you care to show or explain why an acrylate ester cannot be used?

I am using malonate as my C nucleophile and I need carboxylic acid as my end product.  If I used acrylate ester, I am afraid that I would hydrolyze the malonate too.

[Doc Oc]

If you make a benzyl ester you can hydrogenate the acrylic ester to an acid and preserve the malonate esters (if they are standard methy/ethyl esters).

[discodermolide]

Make a TMS ester by treatment with HMDS or TMSCl/Et3N, do your reaction and the TMS group will fall off during the work-up (if not make the work-up slightly acidic)

[orgopete]

There really are a variety of different esters that should allow selective cleavage under a variety of conditions (acid, base, anhydrous, aqueous, nucleophilic, oxidative, reductive, or activation methods). I concede that it may be difficult to find one that is compatible with the Michael addition reaction, however if it were my problem, I would be willing to drop back a step and seek an incremental solution. Specifically, if the Michael addition fails with the best case for the coupling reaction, I wouldn't spend my time trying for a slam dunk solution. If the Michael addition succeeds, then I would begin checking to see if I could get the reaction to succeed with either a minimum amount of ester exchange or probably worst of all, running the reaction in the alcohol of my cleavable ester. I would solve these incrementally.

[taurean]

There really are a variety of different esters that should allow selective cleavage under a variety of conditions (acid, base, anhydrous, aqueous, nucleophilic, oxidative, reductive, or activation methods). I concede that it may be difficult to find one that is compatible with the Michael addition reaction, however if it were my problem, I would be willing to drop back a step and seek an incremental solution. Specifically, if the Michael addition fails with the best case for the coupling reaction, I wouldn't spend my time trying for a slam dunk solution. If the Michael addition succeeds, then I would begin checking to see if I could get the reaction to succeed with either a minimum amount of ester exchange or probably worst of all, running the reaction in the alcohol of my cleavable ester. I would solve these incrementally.

Guys,

Thank you very much for all your suggestions.

Instead of going through the selective ester cleavage, I would prefer if I can get the reaction done in one step using acrylic acid under basic conditions.  Please suggest some conditions.

[discodermolide]

There really are a variety of different esters that should allow selective cleavage under a variety of conditions (acid, base, anhydrous, aqueous, nucleophilic, oxidative, reductive, or activation methods). I concede that it may be difficult to find one that is compatible with the Michael addition reaction, however if it were my problem, I would be willing to drop back a step and seek an incremental solution. Specifically, if the Michael addition fails with the best case for the coupling reaction, I wouldn't spend my time trying for a slam dunk solution. If the Michael addition succeeds, then I would begin checking to see if I could get the reaction to succeed with either a minimum amount of ester exchange or probably worst of all, running the reaction in the alcohol of my cleavable ester. I would solve these incrementally.

Guys,

Thank you very much for all your suggestions.

Instead of going through the selective ester cleavage, I would prefer if I can get the reaction done in one step using acrylic acid under basic conditions.  Please suggest some conditions.

I don't think this will work. As you are using basic conditions you will form the salt of the acid. This will inhibit the Michael addition, as the mechanism requires delocalisation of the pi electrons through into the CO system. to give (in the normal case of an ester, a ketol). If you already have a negative charge placed on this oxygen atom the reaction is very liable not to work.
Use the TMS ester I suggested, but you will not get around making an ester of acrylic acid to get this to work.