Radical Cascade Cyclization Involving C(sp3)-H Functionalization of Unactivated Cycloalkanes

Unactivated cycloalkane is one of the most extensive natural resources, and it is of great significance to develop mild and efficient strategies to achieve C(sp(3))-H of unactivated cycloalkanes. At the same time, the preparation of ring compounds is one of the hotspots in organic synthesis and medicinal chemistry. Because of the advantages of mild conditions and high reactivity, radical cascade cyclization involving C(sp(3))-H functionalization of unactivated cycloalkanes can simultaneously meet the above requirements and synthesize cyclic molecules with potential applications in high atomic- and step-economy manner. In this review, from the point of view of iron catalysis, copper catalysis, and metal-catalyst-free systems, the advances in radical cascade cyclization involving C(sp(3))-H functionalization of unactivated cycloalkanes in recent ten years are summarized.