Concerted or Stepwise? An Experimental and Computational Study to Reveal the Mechanistic Change as a Result of the Substituent Effects

This study investigates the Cope elimination reaction, focusing on the mechanistic shift between concerted and stepwise pathways influenced by substituent effects. Experimental approaches, including kinetic isotope effects (KIEs) and linear free energy relationships (LFERs), alongside density functional theory (DFT) computations, were employed to explore the influence of substituents on the reaction kinetics and pathways. Our findings reveal temperature- and substituent-dependent partitioning between the concerted syn-β elimination and the stepwise E1cB mechanism, providing deeper insights into the mechanistic diversity of elimination reactions.