IRIDOIDS : ENANTIOSELECTIVE SYNTHESIS OF LOGANIN VIA AN ASYMMETRIC DIELS-ALDER REACTION

Article abstract of DOI:10.1016/S0040-4020(01)87559-1

Starting from (-)-camphor-10-sulfonic acid (5) the crystalline sultam 9 was readily prepared.TiCl4-mediated Diels-Alder addition of the N-crotonyl sultam 11 to cyclopentadiene, crystallization of the resulrting 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 norbonanone 20, which upon Baeyer-Villiger oxidation led to the suitably substituted cyclopentane 22 from which 1-B-O-methyl loganin aglucone (2) was readily available.