N,N,N′,N′-Tetramethyl-1,3-propanediamine as the catalyst of choice for the Baylis–Hillman reaction of cycloalkenone: rate acceleration by stabilizing the zwitterionic intermediate via the ion–dipole interaction

N,N,N′,N′-Tetramethyl-1,3-propanediamine (TMPDA) can be used as an efficient catalyst for the Baylis–Hillman reaction of cycloalkenones. The increased reaction rate was thought be derived from the stabilizing effect of the zwitterionic intermediate via the ion–dipole interaction.