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Publication 117  

  1. Iridoids : enantioselective synthesis of loganin via an asymmetric diels-alder reaction
    Vandewalle, M.; Van der Eycken, J.; Oppolzer, W.; Vullioud, C.
    Tetrahedron 1986, 42, 4035-4043

Starting from (-)-camphor-10-sulfonic acid (5) the crystalline sultam 9 was readily prepared. TiCl4-mediated Diels-Alder addition of the N-crotonoyl sultam 11 to cyclopentadiene, crys- tallization of the resulting adduct 12 and subsequent reduction gave virtually pure (1S, 4R, 5R, 6S)-1 together with recovered auxiliary 9. The loganin precursor 1 was transformed into norbornanone 20, which upon Baeyer-Villiger oxidation led to the suitably substituted cyclo- pentane 22 from which 1-B-O-methyl loganin aglucone (2) was readily available.

DOI : 10.1016/S0040-4020(01)87559-1