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

Abstract

Tertiary carbon radicals are usually more stable than secondary carbon radicals, and the hydrogen atom transfer (HAT) from secondary C(sp3)–H bonds to tertiary carbon radicals is normally considered to be a thermodynamically disfavored pathway. Herein, we disclose an unusual protocol involving a C(sp3)–H functionalization enabled by a tertiary cyclopropyl radical and proceeding through hydrogen abstraction from a variety of secondary and tertiary aliphatic C(sp3)–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(sp3)–H functionalization.