Silver-Mediated Indole (4 + 2) Dearomative Annulation with N-Radicals: A Strategy To Construct Heterocycle-Fused Indolines

A regioselective Ag I -mediated dearomative (4 + 2) annulation reaction of substituted indoles has been developed. The transformation provides rapid access to functionalized heterocycle fused indoline skeletons with broad functional groups, high atom economy, and an easy-to-handle nature in one step. Moreover, the recovery experiment of silver catalysts could reduce the cost. Density functional theory (DFT) studies support a “radical cation” pathway in which C–N bond formation determines the rate-limiting step.