Radical strategies for chemodivergent cyclization reactions

Chemodivergent reactions provide a unique platform for accessing expanded chemical space and diverse molecular structures from similar starting materials. The concept of tunable chemoselectivity can be realized by simple modifications to the substrate or reaction conditions. Among the known chemodivergent transformations, radical reactions have emerged as an exceedingly powerful toolbox for their simplicity and efficiency, creating a feasible path to achieve tunable chemoselectivity. This review focuses on recent progress since 2018 in controlling the different reaction pathways in radical cyclization reactions; substrate-dependent reactions, controlled by chain length, substituents and radical precursors, and condition-controlled reactions, mainly dominated by catalysts, bases, redox reagents, solvents, etc. Future avenues for investigation are also presented to help expand this exciting field.