The rates of equilibrium of eight quaternary pyridinium salts containing activated methylene groups with the corresponding ylides have been measured in DMSO solution containing strong bases (DBU, MTBD and P1-tBu). The effect of the ring substituents on the deprotonation rate is greater than that of the methylene substituents. This observation is consistent with the energy of C–H⋯ N hydrogen bonds and the elongation of the C–H ...
