Construction of Indole Structure on Pyrroloindolines via AgNTf<sub>2</sub>-Mediated Amination/Cyclization Cascade: Application to Total Synthesis of (+)-Pestalazine B
N-linked indole structure was constructed on the 3a-position of pyrroloindoline derivatives via a cascade process involving silver-mediated amination of bromopyrroloindolines with 2-ethynylanilines with subsequent 5-endo-dig cyclization. In this reaction, AgNTf2 was used as a tandem reagent, which activated the bromo group as a σ-Lewis acid and the alkyne moiety as a π-Lewis acid. Switching from the initial