Metal‐Free Synthesis of Oxindole‐Based Sulfones via 1,4‐Cyano Migration/Cyclization Through Radical SO ₂ Insertion

Oxindole‐based sulfones are privileged structures found in bioactive compounds and natural products. Herein, a three‐component reaction of unactivated alkenes, potassium metabisulfite, and aryldiazonium tetrafluoroborates has been developed to access oxindole‐based sulfones through a 1,4‐cyano migration/cyclization process. Mechanistic studies indicate that the reaction proceeds through a radical pathway and confirm the intermediacy of aryl, sulfonyl, and iminyl radicals.