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

Abstract 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.