Enantioselective Synthesis of Planar-Chiral Transition-Metal Complexes by Homogeneous Olefi n-Metathesis Reactions and Their Application in Asymmetric Catalysis

摘要

Planar-chiral transition-metal complexes are important chiral scaffolds in organic and organometallic chemistry and have been utilized as chiral ligands, chiral catalysts, or chiral building blocks. In spite of the usefulness of the planar-chiral species in asymmetric synthesis, enantiomerically enriched forms of these compounds are primarily obtained by rather classical methods. Indeed, examples of catalytic enantio-control of planar chirality in transition-metal complexes have been extremely rare, and this has been still a developing area in this fi eld. In this account, recent results from our research group on the catalytic asymmetric synthesis of various planar-chiral transition-metal complexes are outlined. The Mo-catalyzed asymmetric ring-closing metathesis has been found to be a powerful method to control the planar chirality in various transition-metal complexes such as ferrocenes, ruthenocenes, (π-arene)chromium complexes, cymantrene derivatives, etc. Application of the highly enantiomerically enriched planar-chiral complexes in asymmetric synthesis has been also demonstrated.