Access to Chiral HWE Reagents by Rhodium-Catalyzed Asymmetric Arylation of γ,δ-Unsaturated β-Ketophosphonates

Asymmetric arylation of γ,δ-unsaturated β-ketophosphonates with arylboronic acids is reported. By using the (R)-diene* ligated rhodium(I) chloride complex as a catalyst under none basic conditions, the corresponding β-ketophosphonates bearing a δ-chiral center were obtained in high yields (up to 99%) with good to excellent enantioselectivities (up to >99% ee). The enantioenriched products can be readily converted to diverse chiral β′-aryl enones by the Horner–Wadsworth–Emmons reaction.