Palladium-Catalyzed Alkyl Amination of Olefins via Radical-Polar Crossover at Room Temperature

In contrast to traditional ground-state palladium-catalyzed alkyl Heck reactions, which are thermodynamically unfavorable and endothermic, excited-state palladium catalysis facilitates single-electron mechanisms, with light primarily driving the formation of alkyl radicals from triplet-state Pd(0). Here, we report a novel and mechanistically distinct Pd-catalyzed reaction, where the key hybrid alkyl Pd(I)-radical intermediate is generated by the halogen atom transfer (XAT) from alkyl bromide to the Pd(0) at room temperature, without the need for photoinitiation. This hybrid species engages in the addition to dienes and conjugated enynes, producing a transposed open-shell allyl Pd(I)-radical, which undergoes radical-polar crossover (RPC) to yield the desired products. Density functional theory (DFT) studies offer insights into the reaction mechanism, confirming the involvement of hybrid alkyl/allyl Pd(I) radical species as key intermediates.