Transition-state aromaticity and its relationship with reactivity in pericyclic reactions

• Israel Fernández

Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125

• aromatic character in their transition states, this increased aromaticity does not necessarily correlate with lower activation barriers. State-of-the-art computational methods on reactivity, such as the combined activation strain model (ASM)–energy decomposition analysis (EDA) method, reveal that factors

• other than aromaticity govern the barrier heights of these pericyclic reactions. Keywords: activation barrier; activation strain model; aromaticity; computational chemistry; transition state; Introduction Aromaticity is arguably one of the most fundamental and extensively studied concepts in chemistry

• is not behind the observed acceleration in the catalyzed reactions. Once we found that neither aromaticity nor favorable orbital (HOMO(diene)–LUMO(dienophile)) interactions are responsible for the faster rates exhibited by the catalyzed reactions, we applied the activation strain model (ASM) of