Cationic Vanadium(IV) Complexes as Efficient Catalysts for Nazarov Cyclizations

Authors

  • Irene Walz,

    1. Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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  • Andreas Bertogg,

    1. Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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  • Antonio Togni

    1. Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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Abstract

Vanadium(IV) species generated in situ from V(salen)Cl2 complexes (1) by reaction with 2 equiv. of AgSbF6 are effective catalysts for Nazarov cyclizations. Thus, dialkenyl ketones bearing α-ester groups are efficiently converted to corresponding cyclopentenones in good yields at room temperature, in the presence of 2 mol-% catalyst. Under such conditions full conversion takes place within minutes for substrates bearing an electron-donating group at position 1 of the 1,4-dien-3-one system.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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