Access to Enoylhydrazones: Pd-Catalyzed Carbonylative Coupling of Alkynes and Hydrazones

Conventional routes to enoylhydrazones frequently suffer from restricted substrate compatibility and inadequate regiocontrol. To tackle this persistent limitation, we present a robust palladiummediated carbonylative coupling between alkynes and hydrazones, delivering unsaturated enoylhydrazones with exceptional regiochemical fidelity. This protocol exhibits broad functional group compatibility, operates under mild conditions, and is amenable to gram-scale synthesis, thus resolving the sluggish reactivity typically associated with less nucleophilic hydrazone derivatives. Mechanistic investigations reveal that the transformation proceeds via a welldefined Pd(0)/Pd(II) cycle, incorporating CO with near-quantitative atom efficiency, underscoring its alignment with sustainable synthesis goals.