Lending Handedness to the Cyclopentadienyl Ligand

摘要

Chirality (handedness) represents an intrinsic property of many objects (such as hands and some molecules). The increasing demand for just one isomer of a compound, especially for Pharmaceuticals, has been met largely by purifying racemic mixtures of chiral compounds. A powerful alternative to separation is to use chiral catalysts (1) to generate only the desired enan-tiomer; chiral metal complexes bearing specialized ligands based on heteroatoms such as phosphines and N-heterocyclic carbenes have been commonly used. In contrast, on pages 504 and 500 of this issue (2, 3), the authors achieved highly asymmetric C-H functionalizations (4) (see the figure, panel A) by introducing chiral features to one of the most common ligands used in organo-metallic chemistry, cyclopentadienyl (Cp).