Alkene Hydrobenzylation by a Single Catalyst That Mediates Iterative Outer-Sphere Steps.

Cross-coupling catalysts typically react and unite functionally distinct partners via sequential inner-sphere elementary steps: coordination, migratory insertion, reductive elimination, etc. Here, we report a single catalyst that cross-couples styrenes and benzyl bromides via iterative outer-sphere steps: metal-ligand-carbon interactions. Each partner forms a stabilized radical intermediate, yet heterocoupled products predominate. The system is redox-neutral and, thus, avoids exogenous oxidants, resulting in simple and scalable conditions. Numerous variations of alkene hydrobenzylation are made possible, including access to the privileged heterodibenzyl (1,2-diarylethane) motif and challenging quaternary carbon variants.