Fluorine as a Regiocontrol Element in the Ring Opening of Bicyclic Aziridiniums

Authors

  • Yu-hong Lam,

    1. Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA, (phone: +1-310-206-0515; fax: +1-310-206-1843)
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  • Kendall N. Houk,

    Corresponding author
    1. Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA, (phone: +1-310-206-0515; fax: +1-310-206-1843)
    • Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA, (phone: +1-310-206-0515; fax: +1-310-206-1843)

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  • Janine Cossy,

    1. Laboratoire de Chimie Organique, ESPCI ParisTech, CNRS, 10 rue Vauquelin, FR-75231 Paris Cedex 05, (fax: +33-1-40794660)
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  • Domingo Gomez Pardo,

    1. Laboratoire de Chimie Organique, ESPCI ParisTech, CNRS, 10 rue Vauquelin, FR-75231 Paris Cedex 05, (fax: +33-1-40794660)
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  • Anne Cochi

    1. Laboratoire de Chimie Organique, ESPCI ParisTech, CNRS, 10 rue Vauquelin, FR-75231 Paris Cedex 05, (fax: +33-1-40794660)
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Abstract

The origin of the variation in the regioselectivity of the nucleophilic ring opening of a series of bicyclic aziridinium ions derived from N-alkylprolinols was investigated by quantum-chemical computations (M06-2X/6-31+G(d,p)-SMD). These aziridiniums differ only in the degree and the configurations of F-substitution at C(4). With the azide ion as nucleophile, the ratio of the piperidine to the pyrrolidine product was computed. An electrostatic gauche effect influences the conformation of the adjoining five-membered ring in the fluorinated bicyclic aziridinium. This controls the regioselectivity of the aziridinium ring opening.

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