Chiral Bis(binaphthyl) Cyclopentadienyl Ligands for Rhodium-Catalyzed Desymmetrization of Diarylmethanes via...

Owing to substantial advances in the past several decades, transition-metal-catalyzed asymmetric reactions have garnered considerable attention as pivotal methods for constructing chiral molecules from abundant, readily available achiral counterparts. These advances are largely attributed to the development of chiral ligands that control stereochemistry through steric repulsion and other noncovalent interactions between the ligands and functional groups or prochiral centers on the substrates. However, stereocontrol weakens dramatically with increasing distance between the reaction site and the functional group or prochiral center. Herein, we report a symphonic strategy for remote stereocontrol of Rh(III)-catalyzed asymmetric benzylic C-H bond addition reactions of diarylmethanes in which the two aryl motifs differ at the meta and/or para position. Specifically, catalysts bearing a new type of chiral cyclopentadienyl (Cp) ligand differentiate between the two aromatic rings of the diarylmethane by arene-selective η⁶ coordination, setting up an opportunity for ligand-controlled stereoselective benzylic deprotonation and subsequent stereoselective addition to the 1,1-bis(arylsulfonyl)ethylene.