N-Fluorobenzenesulfonimide as a highly effective Ag(i)-catalyst attenuator for tryptamine-derived ynesulfonamide cycloisomerizationElectronic supplementary information (ESI) available: NMR spectra of all the new compounds, crystallographic data in CIF and DFT calculation details. CCDC 1550850. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c9ob00059c

N -Fluorobenzenesulfonimide (NFSI) was identified for the first time as a highly effective Ag( i )-catalyst attenuator in the annulation of a tryptamine-derived ynesulfonamide to azepino[4,5- b ]indole derivatives. Substrate tolerances were examined thoroughly and a plausible mechanism was proposed. The interaction between the Ag( i ) catalyst and NFSI was probed by density functional theory (DFT) calculations. This study provided a highly efficient method to synthesize azepino[4,5- b ]indole derivatives. N -Fluorobenzenesulfonimide was identified for the first time as a unique Ag( i )-catalyst attenuator in the annulation of a tryptamine-derived ynesulfonamide to an azepino[4,5- b ]indole.