Transition States of Binap–Rhodium(I)-Catalyzed Asymmetric Hydrogenation: Theoretical Studies on the Origin of the Enantioselectivity

Authors

  • Seiji Mori  Prof.,

    1. Faculty of Science, Ibaraki University Bunkyo, Mito 310-8512, Japan, Fax: (+81) 29-228-8403
    2. Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University Atlanta, GA 30322, USA, Fax: (+1) 404-727-7412
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  • Thom Vreven  Dr.,

    1. Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University Atlanta, GA 30322, USA, Fax: (+1) 404-727-7412
    2. Gaussian, Inc. 340 Quinnipiac St. Bldg 40, Wallingford, CT 06492, USA
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  • Keiji Morokuma Prof.

    1. Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University Atlanta, GA 30322, USA, Fax: (+1) 404-727-7412
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Abstract

By using the hybrid IMOMM(B3LYP:MM3) method, we examined the binap–RhI-catalyzed oxidative-addition and insertion steps of the asymmetric hydrogenation of the enamide 2-acetylamino-3-phenylacrylic acid. We report a path that is energetically more favorable for the major enantiomer than for the minor enantiomer. This path follows the “lock-and-key” motif and leads to the major enantiomeric product via an energetically favorable binap–dihydride–RhIII–enamide complex. Our theoretical results are consistent with the mechanism that takes place via RhIII dihydride formation, that is, oxidative addition of H2 followed by enamide insertion.

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