Dimeric Cu(I) Hydride‐Catalyzed Alkene Hydrogenation and Imine Olefination: Mechanistic Insights Into Stereocontrol

This work employs density functional theory to elucidate the mechanism of CuH‐catalyzed reductive cross‐coupling between activated alkenes and imines for stereoselective C═C bond formation. Computational analysis reveals that dinuclear CuH complexes are not only thermodynamically more stable than their mononuclear analogues but also feature a sterically congested coordination environment that enforces an outer‐sphere hydrogen migration pathway—enabling direct formation of the key anionic intermediate INT1a . INT1a then undergoes nucleophilic addition to the imine ( R2 ), a step critically facilitated by potassium pyridin‐4‐olate ( KOpyr ), which simultaneously stabilizes the developing negative charge on the imine nitrogen and coordinates to the Bpin oxygen in the ensuing intermediate INT3 . Conformational reorganization via C a ─C c bond rotation in INT3 generates a well‐defined, low‐energy geometry that preorganizes the system for antielimination, thereby ensuring stereospecific E‐olefin formation and underpinning the high diastereoselectivity observed experimentally. Furthermore, this study identifies a cooperative electronic role of the Bpin group in R1 during C═C bond activation and demonstrates that cis–trans isomerization of the E ‐alkene product is both thermodynamically disfavored and kinetically inaccessible under dinuclear CuH catalysis, thereby providing a rigorous, mechanism‐grounded theoretical rationale for the experimentally stereochemical fidelity.