Unveiling Electric Field Catalysis in Lewis Acid-Mediated Ring-Closing Carbonyl–Olefin Metathesis and Oxa Diels–Alder Reactions

Abstract

Electric field (EF) catalysis has emerged as a versatile approach for precisely controlling chemical reactivity and selectivity, which has been explained by theory and demonstrated by experiments. This DFT study explores how Lewis acids create internal electric fields that enhance ring-closing carbonyl–olefin metathesis (RCCOM) and examines the impact of external electric fields on electron transfer in LA-catalyzed Oxa Diels–Alder (ODA) reactions between cyclopentadiene and formaldehyde. In RCCOM, Lewis acids create strong electric fields aligned with the reaction path that help to mix ionic and covalent character. This realigns electron orbitals, enabling a smoother, ionic-like pathway during key steps like cycloaddition and carbonyl–ene reactions.1 The internal EF works together with traditional Lewis acid effects to boost catalysis. In the ODA reaction, external EFs speed up the reaction in one direction while slowing it in the opposite. The inhibition reaches maximum at the electrostatic resistance point (ERP).2,3 Strong inhibitory EFs can override the usual Lewis acid catalysis and switch over to Lewis base catalysis through a different electron demand pathway.4 This makes the EF a useful tool to adjust reactivity,5 switch between Lewis acid and base roles, and a probe to explore electron transfer behavior in complex mechanisms.