A Class of Readily Tunable Planar‐Chiral Cyclopentadienyl Rhodium(III) Catalysts for Asymmetric C–H Activation

Abstract

Chiral half‐sandwich cyclopentadienyl rhodium(III) (CpRhIII) complexes are powerful catalysts for promoting asymmetric C−H activation reactions. Their preparation normally involved linking or embedding the Cp motif to or into a certain chiral backbone to forge the so‐called chiral Cp ligand. However, preparation of a planar‐chiral CpRhIII catalyst bearing a non‐chiral Cp ligand remains a formidable challenge and is rarely reported. We describe herein an unusual class of planar‐chiral rhodium catalysts bearing non‐chiral Cp ligands. Different from existing ones, this catalyst is readily tunable. Ten planar‐chiral only CpRhIII catalysts were prepared with ease, and successfully used in two enantioselective C−H activation reactions. Given its convenient synthesis and high structural tunability, these catalysts are expected to find more utilities in asymmetric C−H activation.