1,3-Dipolar character of six-membered aromatic rings. Part XXIX. Kinetic rates and equilibria for the addition of 2π-electron addends to 3-oxidopyridinium betaines

Abstract

The rates of addition of methyl acrylate to 1-substituted 3-oxidopyridiniums increase with the electron-withdrawing power of the substituent: Me < CH₂Ph < Ph < 4,6-dimethylpyrimidin-2-yl. The rates of addition of vinyl compounds, CH₂:CHR to 1-(pyrimidin-2-yl)-3-oxidopyridinium increase in the series R = OBuⁿ< Ph < CN < 4-pyridyl < CO₂Me. Rates of addition of methyl acrylate to the pyrimidinyl betaine are but little affected by solvent polarity.