• Title/Summary/Keyword: 3,5-Dibromo-2-pyrone

Search Result 5, Processing Time 0.019 seconds

Total Synthesis of (±)-Aspidospermidine Starting from 3-Ethyl-5-bromo-2-pyrone

  • Cho, Hyun-Kyu;Tam, Nguyen Thanh;Cho, Cheon-Gyu
    • Bulletin of the Korean Chemical Society
    • /
    • v.31 no.11
    • /
    • pp.3382-3384
    • /
    • 2010
  • A new synthetic route to ($\pm$)-aspidospermidine was devised, starting from the cycloadduct of 3-ethyl-5-bromo-2-pyrone with vinyl sulfide through a tandem conjugate addition-alkylation sequence. The requisite 3-ethyl-5-bromo-2-pyrone was prepared via the C3-selective Pd-catalyzed coupling reaction with $Et_3Al$-dimethylaminoethanol complex.

NMR Signal Assignments of the Stereochemical Cycloadducts of Bicyclolactone via Diels-Alder Reaction

  • Kim, Dae-Sung;Seo, Chan-Woo;Cho, Cheon-Gyu;Won, Ho-Shik
    • Journal of the Korean Magnetic Resonance Society
    • /
    • v.8 no.1
    • /
    • pp.62-69
    • /
    • 2004
  • Bicyclolactones obtained from the Diels-Alder cycloaddition of 3,5-dibromo-2-pyrone can undergo various palladium catalyzed cross coupling reactions to afford aryl bicyclolactones. The resulting coupled products can be readily converted into various 3-OH cyclohexenes via lactone ring openings, while those bearing dienyl units underwent highly diastereoselective Diels-Alder cycloadditions with selected dienophiles to funish multiply functionalized polycarbocycles. Bromo-bicyclic diene furnished two different diastereomers endo-form (62%) and exo-form (38%) upon cycloadditions with N-Et maleimide (NEM), and their stereochemistries were identified with NMR.

  • PDF