Molecular Catalyst Research Division

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Toward Novel Carbon-Carbon Bond Formation by Organometallic Chemistry

Professor Tamotsu TAKAHASHI Extraordinaly Professor 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.

Scheme 1. Coupling of R-Cp or Indenyl Ligand with Diene Moiety of Zirconacyclopentadienes. Scheme 2. Molybdenum-Catalyzed Kinetic Resolution of Planar-Chiral (-Arene)chromium Complex.