Catalytic Asymmetric C-H Arylation of (η⁶-Arene)Chromium Complexes: Facile Access to Planar-Chiral Phosphines

A catalytic asymmetric direct C-H arylation of (η⁶-arene)chromium complexes to obtain planar-chiral compounds is reported. The use of the hemilabile ligand H₈-BINAP(O) is key to providing high enantioselectivity in this transformation. We show that this methodology opens the door to the synthesis of a variety of planar-chiral chromium derivatives which can be easily transformed into planar chiral mono- or diphosphines. Mechanistic studies, including synthesis and characterization of Pd and Ag complexes and their detection in the reaction mixture, suggest a Pd-catalyzed/Ag-promoted catalytic system where Ag carries out the C-H activation step.