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(sp 3 )−H activation, 1,2‐addition, and defluorinative S N Ar‐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.