Diastereoselective Synthesis of N-Substituted Planar Chiral Ferrocenes Using a Proline Hydantoin-Derived Auxiliary

An N‐substituted ferrocene bearing a proline‐derived chiral directing group undergoes diastereoselective lithiation–electrophile quench to give planar chiral products in >95:5 dr. The starting material is synthesized by imidation of iodoferrocene with L‐proline hydantoin, followed by hydrosilylation. Although the auxiliary is stable to lithium bases of the types RLi and R2NLi, the ortho‐substituted products may be converted to solely planar chiral derivatives with simple reagents thanks to a labile triethylsilyloxy moiety.