The Morita-Baylis-Hillman reaction (the reaction between a Michael acceptor and an aldehyde catalyzed by a tertiary amine) is characterized by its ability to produce densely functionalized products in the absence of products of major side reactions.  The major drawback of the reaction is that it proceeds extremely slowly, and completion times, even in the absence of solvent, are typically on the order of days.  It is known that protic solvent additives and Lewis acid additives (e.g. Sc(OTf)3 accelerate the reaction, but the reaction rates, especially with ester Michael acceptors, remains slow.  We have examined the effects of adding alcohols to the DABCO-catalyzed reaction between p-nitrobenzaldehyde and ethyl acrylate in CD3CN, and find that the effects of a wide range of added alcohols on the value of the rate constant are actually quite small, with a doubling of the pseudo-third order rate constant of the reaction being the largest enhancement that we have observed.  Interestingly, the rate enhancement by polyols appears to correlate with the number of hydroxymethyl (not hydroxyl) groups in the polyol.

Limitations on acceleraion of the Morita-Baylis-Hillman
reaction by alcohols

239th National Meeting (2010)

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Limitations on acceleraion of the Morita-Baylis-Hillman reaction by alcohols