[nj_bartel]

I was planning on running a Bayliss-Hillman with benzaldehyde, methyl cinnamate, and an imidazole compound catalyst.  Would 3-pentanone work as a solvent or would it compete with the methyl cinnamate in reacting with the imidazole compound?  Any solvent recommendations?

[Dan]

I was planning on running a Bayliss-Hillman with benzaldehyde, methyl cinnamate, and an imidazole compound catalyst. 

Any specific reason you are using imidazole? I'm not an expert on these reactions but I was under the impression that DABCO, DMAP and DBU are the most common.

Would 3-pentanone work as a solvent or would it compete with the methyl cinnamate in reacting with the imidazole compound? 

The (initial) reaction of the methyl cinnamate with the base would be a conjugate addition, forming an enolate. Since pentan-3-one is not alpha,beta-unsaturated I don't think this will be a problem.
However, pentan-3-one could, I expect, act as an electrophile and accept the cinnamate enolate. Since it is a solvent and in massive excess, I suspect this will be a major complication ie. it will compete with the benzaldehyde.

Any solvent recommendations?

What does the literature recommend? I don't know, I haven't looked into this reaction in detail, but if you're going to do it in the lab then you probably should read some papers first. I'd suggest a solvent that is not electrophilic or acidic and dissolves your reagents. THF, 1,4-dioxane, DCM, Chloroform, methanol, other alcohols? Perhaps you could even use benzaldehyde as your solvent (although it is a bit of a pain to get rid of)?

[nj_bartel]

Yes, there's a specific reason I'm trying an imidazole compound as the catalyst, and you're right - DABCO, DMAP, DBU and phosphines are the most common catalysts. 

I'm not going back into the lab until Thursday, and don't have access to the real literature again until then.  However, last time I looked I only remembered seeing information on a Bayliss-Hillman run with either ethyl cinnamate or a benzaldehyde, neither at the same time, and neither with an imidazole that I can recall.  Also, the literature that's just available through google doesn't seem to suggest a solvent for any of the Bayliss-Hillman reactions.  Those you suggested should work - I think I was initially too concerned about the solvent being an electrophillic competitor for the catalyst.

Thanks,
Nick

[chittimallasanthoshkumar]

I presume DABCO would be the best catalyst in the presence of polar solvents like all the common polar solvents. But a recent literature precedant shows that sulpholane, N-methylpyrrolidinone, N-methylmorpholine were successful for various sluggish BH reactions (including acrylamides). You can get hold of this manuscript via google (ARKIVOC 2005 (iii) 99-109)

[nj_bartel]

Thanks for the information    I'm not sure if those solvents are compatible with imidazole compounds (I'm pretty sure the sulpholane isn't), but it's worth looking into.