Intermolecular dearomative C2-arylation of N-Ac indoles activated by FeCl3.

We report the FeCl3-mediated direct addition of electron-rich arenes to the C2-position of electrophilic N-Ac indoles under mild conditions (room temperature, air). No functional group is required on the arene nucleophile: one of its C–H bonds is added to the C2=C3 double bond of the indole nucleus in a Friedel–Crafts-type reaction. This dearomatisation process delivered a broad range of C2-arylated indolines. [ABSTRACT FROM AUTHOR]