Thioamide‐Enabled Anodic N‐Centered Radical Cyclizations

An anodic cyclization leading to the 6‐membered ring, bisamine‐heterocyclic core of the chrysosporazine family of efflux inhibitors, has been accomplished. The reactions proceed through a N‐based radical intermediate that is derived from the oxidation of a thioamide anion and benefit strongly from the use of a Cu‐based mediator. Both changes to the more standard anodic cyclization conditions were required to prevent overoxidation of the product. The thioamide product derived from the cyclization was readily hydrolyzed to the amide required for synthesis of the natural products.