Metallocene sulfoxides as precursors of metallocenes with planar chirality

The preparation of metallocene sulfoxides and their ortho-diastereoselective functionalization are described. The applications of enantiopure 1,2- and 1,3-disubstituted metallocenes are reviewed, with special emphasis on the preparation of ligands for asymmetric catalysis. The sulfoxide functionality is a useful, traceless, chiral diastereoselective ortho-directing group, as explained in the article. It allows one to synthesize a wide range of enantiopure metallocenes with planar chirality and predictible configuration. Most of the examples are related to the ferrocene area.