Synthesis and Stereochemistry of Planar-Chiral Cyclopentadienyl Complexes of Late Transition Metals

摘要

Planar chiral cyclopentadienyl complexes of late transition metals were synthesized by using trisubstituted cyclopentadienes. Each enantiomer has been isolated as an optically pure form by fractional recrystallization of (l)-menthyl ester derivatives followed by the removal of the (l)-menthyl group. Cyclopentadienyl ruthenium complexes possessing an anchor phosphine ligand, which prevents the rotation of the cyclopentadienyl ring, were also prepared. The planar-chiral ruthenium complexes showed high diastereoselectivity in some reactions such as complexation of dienes and substitution with phosphines. The planar-chiral ruthenium complexes with anchor phosphine ligands were successfully applied to asymmetric allylic lamination and alkylation. In these reactions, the anchor phosphine ligand acts as an important role to control the stereochemistry of the products.