Synthesis of Benzofuran Derivatives via Cascade Radical Cyclization/Intermolecular Coupling of 2‐Azaallyls

Benzofurans are among the most abundant structural units in bioactive natural products. However, the synthesis of such structures by radical cyclization cascade reactions is rare. Herein we report a mild and broadly applicable method for the construction of complex benzofurylethylamine derivatives through a unique radical cyclization cascade mechanism. Single‐electron‐transfer (SET) from 2‐azaallyl anions to 2‐iodo aryl allenyl ethers initiates a radical cyclization that is followed by intermolecular radical–radical coupling. This expedient approach features a rapid increase in molecular complexity and enables the synthesis of a range of polycyclic benzofurans.

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