Iron‐Catalyzed Trifluoromethylation of Indole‐Tethered Alkene Enables Synthesis of CF3‐Containing Spiroindolenines and Tetrahydrocarbazoles.

An iron‐catalyzed trifluoromethylation of indole‐tethered alkene with Togni's reagent to construct CF3‐containing spiro[indole‐3,3′‐pyrrolidine] and tetrahydrocarbazole derivatives under mild and convenient conditions has been disclosed. Mechanistic studies indicate that the reaction proceed through a CF3 radical addition to the alkene, followed by sequential dearomatizing spiocyclization of the indole and oxidation to afford the spiro[indole‐3,3′‐pyrrolidine] derivatives. Meanwhile, when the substituent at the C2 position of the indole is hydrogen, the CF3‐containing tetrahydrocarbazole is obtained through trifluoromethylation of alkene and cyclization of indole. [ABSTRACT FROM AUTHOR]