A Versatile Ru Catalyst for the Asymmetric Transfer Hydrogenation of Both Aromatic and Aliphatic Sulfinylimines

Authors

  • Óscar Pablo,

    1. Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain), Fax: (+34) 965903549
    Search for more papers by this author
  • Dr. David Guijarro,

    Corresponding author
    1. Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain), Fax: (+34) 965903549
    • Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain), Fax: (+34) 965903549
    Search for more papers by this author
  • Dr. Gábor Kovács,

    1. Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain), Fax: (+34) 935812920
    Search for more papers by this author
  • Dr. Agustí Lledós,

    1. Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain), Fax: (+34) 935812920
    Search for more papers by this author
  • Dr. Gregori Ujaque,

    Corresponding author
    1. Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain), Fax: (+34) 935812920
    • Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain), Fax: (+34) 935812920
    Search for more papers by this author
  • Dr. Miguel Yus

    Corresponding author
    1. Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain), Fax: (+34) 965903549
    • Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante (Spain), Fax: (+34) 965903549
    Search for more papers by this author

Abstract

A highly efficient Ru catalyst based on an achiral, very simple, and inexpensive amino alcohol ligand (2-amino-2-methylpropan-1-ol) has been developed for the asymmetric transfer hydrogenation (ATH) of chiral N-(tert-butylsulfinyl)imines. This complex is able to catalyze the ATH of both aromatic and the most challenging aliphatic sulfinylimines by using isopropyl alcohol as the hydrogen source. The diastereoselective reduction of aromatic, heteroaromatic, and aliphatic sulfinylketimines, including sterically congested cases, over short reaction times (1–4 h), followed by desulfinylation of the nitrogen atom, affords the corresponding highly enantiomerically enriched (ee up to >99 %) α-branched primary amines in excellent yields. The same ligand was equally effective for the synthesis of both (R)- and (S)-amines by using the appropriate absolute configuration in the iminic substrate. DFT mechanistic studies show that the hydrogen-transfer process is stepwise. Moreover, the origin of the diastereoselectivity has been rationalized.

Ancillary