NiH‐Catalyzed Enantioconvergent <i>α</i> ‐Alkenylation of Carbonyl Compounds via Markovnikov Alkyne Hydronickellation

ABSTRACT β ‐Methylene carbonyl motifs constitute privileged structural frameworks that play vital roles as a pharmacophore and serve as key intermediates in the assembly of architecturally complex molecules. Despite their synthetic importance, asymmetric approaches for their preparation remain scarce and are largely confined to substrate‐controlled or stoichiometric chiral auxiliary methods. Herein, we report a nickel hydride‐catalyzed enantioconvergent α ‐alkenylation of carbonyl compounds with alkynes, providing a direct and general route to α ‐chiral β ‐methylene carbonyl derivatives. The transformation proceeds via Markovnikov‐selective alkyne hydronickellation followed by nickel‐radical recombination to forge the α ‐stereogenic center, delivering the desired products with high levels of regio‐ and enantioselectivity. The protocol accommodates a wide range of alkynes and α ‐halocarbonyl partners, displays excellent functional group tolerance, and can be applied to the modification of biologically relevant molecules. Mechanistic investigations indicate that a partially protic Ni(II)H species governs the observed regioselectivity, while enantio‐discrimination occurs during the radical capture step. This work establishes NiH catalysis as a versatile platform for expanding the synthetic repertoire for enantioenriched β ‐methylene carbonyl architectures.