Chiral cyclopentadienyl ligands as stereocontrolling element in asymmetric C-H functionalization.

Metal complexes coordinated by a single cyclopentadienyl (Cp) ligand are widely used, versatile catalysts, but their application to asymmetric reactions has been hindered by the difficulty of designing Cp substituents that effectively bias the coordination sphere. Here, we report on a class of simple C(2)-symmetric Cp derivatives that finely control the spatial arrangement of the transiently coordinated reactants around the central metal atom. Rhodium(III) complexes bearing these ligands proved to be highly enantioselective catalysts for directed carbon-hydrogen (C-H) bond functionalizations of hydroxamic acid derivatives.