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Updated: Jan 15, 2026

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
Photochemical and Thermal Concerted 1,3-Sigmatropic Rearrangements of a π-Extended Methylenecyclopropane
Shunsuke Konrai1, Ma-Aya Takano2, Manabu Abe2
1Department of Chemistry, Graduate School of Science, The University of Osaka, 1-1 Machikaneyama, Osaka 560-0043, Japan.
None:
The reversible interconversion between methylenecyclopropane (MCP) and trimethylenemethane (TMM) has been extensively studied, yet precise control over their spin states remains challenging. Here, we designed and synthesized a propeller-shaped π-extended MCP derivative and its corresponding TMM derivative with anthroxyl moieties. The MCP derivative was isolated as a stable compound, and upon photoirradiation, it generated the triplet-state TMM derivative, which reverted to the MCP derivative without decomposition. In contrast, thermal excitation induced a unique carbon-carbon bond fluxionality within the MCP core via a concerted 1,3-sigmatropic rearrangement rather than a stepwise diradical pathway. These findings demonstrate that external stimuli such as light and heat enable spin-state control and dynamic bond fluxionality, providing new insights into organic stimuli-responsive materials.
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