A ligand-controlled regiodivergent three-component Heck-Tsuji reaction utilizing umpolung hydrazones enabled by palladium catalysis.

Developing sustainable, selective strategies for the multicomponent functionalization of allenes remains an ongoing challenge in synthetic chemistry. We report a ligand-controlled, regiodivergent palladium-catalyzed three-component Heck-Tsuji reaction of allenes, aryl iodides, and umpolung hydrazones. Leveraging the umpolung reactivity of hydrazones as sustainable carbanion surrogates enables the direct arylalkylation of allenes, forming two C-C bonds in a single step. The ligand environment governs reaction outcomes, switching selectivity between branched and linear adducts using simple, commercially available ligands. This method tolerates a wide range of aryl, heteroaryl, and alkyl substrates, operates under mild conditions, and is amenable to late-stage diversification of complex molecules. Computational studies suggest a plausible explanation for the mechanistic basis of the ligand-dependent regioselectivity, providing reasonable insights for design of divergent Pd-catalyzed multicomponent coupling reactions.