Synthesis 2009(9): 1557-1563  
DOI: 10.1055/s-0029-1216635
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart ˙ New York

Enantioselectivity Switch in Direct Asymmetric Aminoxylation Catalyzed by Binaphthyl-Based Chiral Secondary Amines

Taichi Kano, Akihiro Yamamoto, Fumitaka Shirozu, Keiji Maruoka*
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Fax: +81(757)534041; e-Mail: maruoka@kuchem.kyoto-u.ac.jp;
Further Information

Publication History

Received 16 January 2009
Publication Date:
14 April 2009 (online)

Abstract

Binaphthyl-based amino acids (S)-1 and an aminosulfonamide (S)-2 were applied for direct asymmetric aminoxylation with nitrosobenzene. In the presence of either (S)-1 or (S)-2, the aminoxylation of aldehydes proceeded smoothly, and subsequent reduction with NaBH4 gave 2-aminoxyl alcohols with good to excellent enantioselectivities. In each case, binaphthyl-based chiral amine catalysts (S)-1 and (S)-2, which have the identical axial chirality, gave opposite enantiomers as the major product. This method represents a rare example of the direct asymmetric aminoxylation by a non-proline type catalyst.

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CCDC-710886 contains the supplementary crystallographic data of (S)-2˙HCl salt for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.