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Updated: Sep 12, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
A Potassium Base-Promoted Intramolecular Enolate-Olefin Metathesis
Kazuma Sugimoto1, Takaaki Nagao1, Kazuma Kurokawa1
1Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto, 606-8501, Japan.
Abstract:
Polycyclic aromatic hydrocarbons (PAHs) are important structures known for their unique properties. Herein, we present a transition-metal-free method for synthesizing hydroxy-substituted PAHs using base-promoted intramolecular enolate-olefin-metathesis chemistry. 2-Acyl-2'-alkenylbiaryl substrates were subjected to [2 + 2]-/retro-[2 + 2]-cycloaddition sequences to afford functionalized PAH derivatives, including enantiomerically enriched [7]helicenes. Density functional theory (DFT) calculations predicted that ionic and radical intermediates are involved in a stepwise process. Various biaryl substrates, including heteroatom-containing compounds, were successfully converted into the desired PAHs. The developed method also enabled the synthesis of π-extended arenols, thereby offering a sustainable and efficient alternative to transition-metal-catalyzed processes.
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