Kinetic Resolution of α,β-Unsaturated Tertiary Phosphine Oxides via Alkene E → Z Isomerization Catalyzed by a Photoexcited Chiral Copper Complex

Catalytic kinetic resolution (KR) is an efficient method for synthesizing enantiopure compounds from racemic precursors, offering a valuable tool for asymmetric synthesis. In this study, we report a KR reaction enabled by photoexcited chiral copper complex-catalyzed alkene E → Z isomerization, facilitating the direct synthesis of P-chiral phosphine oxides from racemic tertiary phosphine oxides (TPOs). A series of P-chiral α,β-unsaturated TPOs incorporating pyridinyl groups were obtained with up to 98% enantiomeric excess (ee) and up to 354 selectivity factors (S). Both E- and Z-isomers of α,β-unsaturated TPOs were synthesized with high enantiomeric purity. These P-chiral products can be readily converted into a variety of P-chiral derivatives, including potential chiral biphosphine ligands and Lewis base catalysts, demonstrating the versatility of our approach. This work provides a direct route to synthesizing P-stereogenic phosphine oxides from racemic TPOs via asymmetric photoexcited transition metal catalysis.