A Highly Strained Planar-Chiral Platinacycle for Catalytic Activation of Internal Olefins in the Friedel–Crafts Alkylation of Indoles


  • This work was financially supported by the ETH research grant TH-01/07-1 and F. Hoffmann-La Roche. We thank Priv.-Doz. Dr. Martin Karpf and Dr. Paul Spurr (both from F. Hoffmann-La Roche, Synthesis and Process Research, Basel) for carefully reading this manuscript and Paul Seiler and Dr. W. Bernd Schweizer (both from ETHZ) for X-ray crystal structure analysis.


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Activation by deformation: A planar-chiral platinacycle readily prepared by diastereoselective cycloplatination enables the enantioselective intramolecular hydroarylation of indoles having disubstituted Z olefins (see scheme; Ts=p-tolylsulfonyl). Sufficient activity is achieved by a combination of highly strained catalyst geometry and accelerated olefin coordination. This application represents the first highly enantioselective reaction catalyzed by a platinacycle.