Regioisomeric Tuning of Intermolecular Diels‐Alder Reaction by Electrostatic Field‐Dipole Interaction

The effect of an electric field on the regioselectivity of the Diels‐Alder reaction is explored using a zwitterionic iminium ion species as both the dienophile and the source of the electric field. The head‐to‐tail dipolar orientation of the substrates becomes favored in less‐polar solvents and at higher temperatures where the internal electric field is conserved. Computational studies validate the electric field effect on the experimental regioisomeric preferences, in terms of the transition dipole moment, reactant complexation, and transition energy. This work offers deeper insight into the effects of electrostatic fields on chemical reactions, suggesting new directions for controlling reaction selectivity.