Ruthenium-CatalyzedC–H Alkenylation of Phosphines:Reaction Development, Mechanistic Studies, and Applications to LigandDesign

A general and efficient P(III)-directed ruthenium-catalyzed C–H olefination of tertiary phosphines with alkenyl reagents is reported for modular synthesis of axially olefin-phosphines. This late-stage functionalization exhibits broad substrate scope for both phosphines and olefins. A diverse library of 55 olefin–phosphines was prepared in high yields, tolerating up to 15 different functional groups. These ligands demonstrate exceptional performance in Suzuki coupling, achieving catalyst loadings as low as 0.005 mol % and surpassing commercial biarylphosphines in facilitating Pd-catalyzed C–C and C–X bond formations. Mechanistic studies and DFT calculations support a Ru–C addition/β-bromo elimination pathway over oxidative addition.