Radical Cascade Cyclization of Alkene‐Tethered Compounds: Versatile Approach towards Ring‐Fused Polycyclic Structures

Abstract Ring‐fused polycyclic structures widely exist in a myriad of natural products and pharmaceutical molecules. Consequently, the construction of such structures from readily available substrates becomes an important researching topic in organic synthesis. Triggered by the addition of radicals to the (activated or unactivated) double bonds in alkenes, the subsequent intramolecular addition/cyclization leads to polycyclic compounds. Following this procedure, a variety of functionalized ring‐fused structures were formed. Great achievements have been witnessed recently. Those works provided efficient, atom economy, and operational simple approaches toward versatile functionalized polycyclic structures from readily available alkene‐based substrates. Here, we summarized the recent achievements on the formation of ring‐fused polycyclic structures via the radical‐triggered cascade reactions of alkenes. Construction of polycyclic structures with no less than 3 fused rings developed during the last decade were included in this Review, corresponding mechanisms were also discussed.