How does HOTf/HFIP Cooperative System Catalyze the Ring‐Opening Reaction of Cyclopropanes? A DFT Study

Abstract

AbstractDensity functional theory calculations have been performed to probe the detailed mechanisms of Brønsted‐acid‐catalyzed ring‐opening reactions of donor‐acceptor cyclopropanes. The reaction model without consideration of the explicit solvation effect was characterized by a high activation free energy of 29.5 kcal/mol, while inclusion of the explicit solvation effect in calculations lowered the activation free energy to 20.5 kcal/mol, which demonstrated the cooperative role of HOTf and HFIP in facilitating the ring‐opening step. Additionally, we put forward two distinct reaction mechanisms, including the nucleophile‐induced mechanism and the protonation‐induced mechanism, for the ring‐opening step of donor‐acceptor cyclopropanes. Computational results revealed that modulation of the reaction conditions could result in the shift of the reaction mechanisms.