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Palladium-Catalyzed Trimethylenemethane Cycloaddition of Olefins Activated by the σ‑Electron-Withdrawing Trifluoromethyl Group

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journal contribution
posted on 16.09.2015, 00:00 by Barry M. Trost, Laurent Debien
α-Trifluoromethyl-styrenes, trifluoromethyl-enynes, and dienes undergo palladium-catalyzed trimethylenemethane cycloadditions under mild reaction conditions. The trifluoromethyl group serves as a unique σ-electron-withdrawing group for the activation of the olefin toward the cycloaddition. This method allows for the formation of exomethylene cyclopentanes bearing a quaternary center substituted by the trifluoromethyl group, compounds of interest for the pharmaceutical, agrochemical, and materials industries. In the diene series, the cycloaddition operates in a [3 + 4] and/or [3 + 2] manner to give rise to seven- and/or five-membered rings. This transformation greatly improves the scope of the TMM cycloaddition technology and provides invaluable insights into the reaction mechanism.