Theoretical Studies for Switching Regioselectivity in Ruthenium Hydride‐Catalyzed Alkyne Hydroacylation

Abstract Density functional theory (DFT) was used to elucidate and explore ruthenium hydride‐catalyzed intermolecular pent‐2‐yne hydroacylation with three phosphine ligands (PMe 3 , PPh 3 , ferrocene‐based Josiphos L 3 ). Ruthenium‐PMe 3 ‐catalyzed intermolecular pent‐2‐yne hydroacylation had five plausible pathways producing five possible products (β,γ‐unsaturated ketones p1 , p2 , p3 , and α,β‐unsaturated ketones p4 , p5 ), and the α‐Et‐β,γ‐unsaturated ketone p1 was predicted theoretically to be dominant. Three steps (hydrogen migration, nucleophilic reaction, β‐hydrogen elimination) were the rate‐determining step for this pathway affording α‐Et‐β,γ‐unsaturated ketone p1 . In ruthenium‐PPh 3 ‐catalyzed pent‐2‐yne hydroacylation, the rate‐determining step was the β‐hydrogen elimination. In ruthenium‐L 3 ‐catalyzed pent‐2‐yne hydroacylation, the rate‐determining step was also the β‐hydrogen elimination. Furthermore, the similarities and differences of three phosphine ligands were studied and indicated. All results were consistent with Dong's experiments.