Asymmetric 1,3-Dipolar Cycloaddition of Cyclic Nitrones to Crotonic Acid Derivatives Bearing Chiral Auxiliaries. Synthesis of Optically Active β-Amino Acids, (+)-Sedridine, and (+)-Hygroline

Authors:
  • SMShun-Ichi Murahashi
    Shun-Ichi Murahashi
  • YIYasushi Imada
    Yasushi Imada
  • MKMasahiko Kohno
    Masahiko Kohno
  • TKToru Kawakami
    Toru Kawakami
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Abstract
Asymmetric 1,3-dipolar cycloaddition of cyclic nitrones with optically active crotonic acid derivatives bearing chiral auxiliaries in the presence of zinc iodide gives bicyclic isoxazolidines, which are precursors of ß-amino acids, highly stereoselectively. By using these reactions (+)-sedridine (4) and (+)-hygroline (5) can be synthesized readily.