Planar Chiral Ligands:Design and Applications in Asymmetric Synthesis

Chiral ligands play an important role in asymmetric synthesis. Among them the ligands having planar chirality attract more interesting of organic chemists because of their unique structure. Recently, some new types of planar chiral ligands, including 1,1'-disubstituted ferrocene 1, bis(ferrocene carboxylic)diaminocyclohexane 2, and benzylic substituted cyclophane 3, are synthesized (Scheme 1)^1]. These chiral ligands have been successfully used in asymmetric allylic alkylation, Heck reaction, etc. The role of planar chirality in asymmetric induction by using NMR and X-ray are also studied.