Asymmetric Synthesis of Enantiopure 1,2-Disubstituted Ferrocenes

Kagan et al. have reported the synthesis of planar-chiral 1,2-disubstituted ferrocenes 3 using chiral sulfinyl ferrocenes 1. According to the report, lithiation of 1 by LDA and the following reaction with various electrophiles affords o-substituted products 2. Then, lithiation of 2 by t-BuLi and the following reaction with electrophiles affords planar-chiral 1,2-disubstituted ferrocenes 3 with high stereoselectivity. These ferrocenes are expected to be used for various applications like chiral ligands.