Iron-Catalyzed Regiospecific Intermolecular Radical Cyclization of Anilines: Strategy for Assembly of 2,2-Disubstituted Indolines.

The first regiospecific catalytic intermolecular assembly of 2,2-disubstituted indolines has been developed. This protocol is based on a ligand and directing group free, iron-catalyzed radical [3 + 2] process, allowing efficient coupling of different N-sulfonylanilines with various α-substituted styrenes. Preliminary mechanistic studies elucidated the radical mechanism involving a reactive and versatile anilino radical and the importance of iron complex as a Lewis acid, rendering both the reactivity and regiospecificity of this transformation.