Investigation of substituent effect on the Johnson-Claisen rearrangement: A DFT approach

The uncatalyzed Johnson-Claisen rearrangement has been investigated at the B3LYP/6-311G(d,p) level of theory. The effect of electron donating and electron withdrawing substitutions in different positions on the transition state has been studied. Our results show that electron-donating substituents accelerate rearrangement while electron-withdrawing substituents act in opposite direction and decelerate the reaction. The amount of acceleration or deceleration depends on substituent position. In addition to mono-substituted compounds, di-substituted compounds have been also investigated. All of the calculations have been carried out in gas phase.