Fe-Catalyzed Regioselective C(sp³)–H-Abstraction by Tertiary Cyclopropyl Radicals

Tertiary carbon radicals are usually more stable than secondary carbon radicals, and the hydrogen atom transfer (HAT) from secondary C(sp 3 )–H bonds to tertiary carbon radicals is normally considered to be a thermodynamically disfavored pathway. Herein, we disclose an unusual protocol involving a C(sp 3 )–H functionalization enabled by a tertiary cyclopropyl radical and proceeding through hydrogen abstraction from a variety of secondary and tertiary aliphatic C(sp 3 )–H bonds. The reaction can furnish valuable, densely functionalized cyclopropane derivatives. Sufficient mechanistic experiments and density functional theory (DFT) calculations have provided theoretical insights into the chemo- and regioselectivity in this underexplored HAT protocol. The method features broad functional group compatibility and high product diversity and offers a new prospect for radical C(sp 3 )–H functionalization.