Synthesis of 6/5/3-Fused Tricyclic Scaffolds via Multistep Cascade Cyclization of α‑Aryl Vinylsulfoniums with <i>para</i>-Quinamines and <i>para</i>-Quinols

Herein, we present a straightforward approach to access hydroindoline-5-one-based 6/5/3-fused polycyclic ring structures through multistep cascade reactions involving α-aryl vinylsulfoniums and <i>para</i>-quinamines. The reactions proceed smoothly under mild conditions to deliver the desired products in generally good isolated yields. This protocol is also applicable to the cascade cycloaddition reactions of α-aryl vinylsulfoniums and <i>para</i>-quinols, effectively generating complex tricyclic scaffolds. In addition, the scale-up synthesis and further derivatizations demonstrate the potential synthetic application of the protocol.