NIS-Promoted Cascade Electrophilic Spirocyclization of Aryl Alkyne-Tethered Indoles to Construct Iodinated Spiroindolenines

A highly efficient and general cascade electrophilic spirocyclization reaction of aryl alkyne-tethered indoles with <i>N</i>-iodosuccinimide (NIS) has been developed under mild conditions. A diverse range of iodinated spiroindolenines were successfully constructed in moderate to excellent yields without relying on metal reagents, strong oxidants, photochemical activation, or electrochemical assistance. Moreover, this protocol demonstrates good functional group tolerance, mild reaction conditions, feasibility for gram-scale synthesis, and versatile practical applications.