Molecular Catalyst Research Division
Toward Novel Carbon-Carbon Bond Formation by Organometallic Chemistry
Tamotsu TAKAHASHI Jiro KASAHARA
Cleavage/formation of carbon-carbon bonds in organic molecules have been a major challenge in synthetic organic chemistry. By utilizing transition-metal reagents or catalysts, our research group has developed such reactions with unique modes of C-C bond cleavage/formation or interesting stereoselectivity.
Cyclopentadienyls in metallocene species are usually functioning as ancillary ligands and rarely involved in the final organic products at the metallocene-mediated transformations. It was found recently that treatment of various zirconacyclopentadiene species with titanium (IV) chloride facilitated coupling reactions between a η5-cyclopentadienyl (or η5-indenyl) ligand and the dienic moiety to afford the corresponding indene (or fluorene) derivatives in high yields (Scheme 1).
Kinetic resolution of a racemic planar-chiral (π-arene)chromium complex by Mo-catalyzed ring-closing metathesis was realized (Scheme 2). This is a rare example of catalytic asymmetric induction of planar chirality in transition-metal complexes.