Baylis−Hillman Mechanism: A New Interpretation in Aprotic Solvents

Using reaction rate data collected in aprotic solvents, we have determined that the Baylis−Hillman rate-determining step is second order in aldehyde and first order in DABCO and acrylate. On the basis of these data, we have proposed a new mechanism involving a hemiacetal intermediate. The proposed mechanism was then supported using two different kinetic isotope experiments.