Synthesis of Indolines via Base‐Mediated C–H Activation and Defluorinative C–N Coupling, with no Need for Transition‐Metals

Syntheses of (partially) aromatic nitrogen heterocycles increasingly rely on transition‐metal catalyzed C–C‐ and C–N‐cross‐coupling reactions. Here we describe a different approach to the synthesis of indolines by a domino C(sp3)–H activation, 1,2‐addition, and defluorinative SNAr‐cyclization sequence to provide the target 1,2‐diarylindolines (1,2‐diaryl‐2,3‐dihydroindoles) from ortho‐fluorinated methyl‐arenes and N‐aryl imines (benzylidene anilines) in a cyclocondensation that is mediated by potassium hexa­methyl­di­silazide (KHMDS) as base exclusively. This transition‐metal‐free process via C–H and C–F bond activation provides a one‐step entry into a wide array of indoline scaffolds (43 examples, up to 96% yield). This privileged substructure is common in natural products and pharmaceuticals alike, and cannot be accessed by traditional condensation reactions.