Reexamination of the traditional Baylis–Hillman reaction

In the Baylis–Hillman reaction of arylaldehydes with methyl vinyl ketone (MVK), we found that, besides the normal Baylis–Hillman adduct , the diadduct can also be formed at the same time and the yield of can reach to 55% if increasing the amount of methyl vinyl ketone. But for ethyl vinyl ketone (EVK), methyl acrylate or acrylonitrile, only the normal Baylis–Hillman adduct , or was obtained, respectively. The substituentʹs effects and Lewis base effects were also examined and a plausible reaction mechanism was proposed for the formation of .