Divergent Synthesis of 3‐Trifluoroethyl Benzofurans Through Rh‐Catalyzed CC Bond Activation Coupled with Transfer Hydrogenation

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The strategic incorporation of the pharmacologically privileged trifluoroethyl group into the biologically significant benzofuran scaffold offers considerable potential for medicinal and agrochemical applications. Herein, an atom‐economical synthetic approach to 3‐trifluoroethyl benzofurans through Rh‐catalyzed cascade reaction of readily available trifluoromethyl alkene‐tethered benzocyclobutenols is reported. This transformation proceeds via a mechanistically intricate sequence involving CC bond activation, migratory insertion, β ‐hydride elimination, chain walking, and transfer hydrogenation. By modulation of reaction conditions, both intermolecular and intramolecular transfer hydrogenation pathways have been developed, leading to the divergent synthesis of 4‐ β ‐keto‐ and 4‐ β ‐hydroxy‐substituted 3‐trifluoroethyl benzofurans.