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

A regioselective AgI-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 easy 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.