Radical cyclisation reactions leading to polycyclics related to the Amaryllidaceae and Erythrina alkaloids

A F Parsons, D A J Williams

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Novel radical cyclisation reactions, mediated by tributyltin hydride, samarium(II) iodide or manganese(III) acetate, have been explored to form tri- and tetra-cyclic ring systems related to the Amaryllidaceae or Erythrina family of alkaloids. Haloethanamide precursors possessing a cyclohexenone ring have been shown to form octahydroindolones, and erythrinane-type systems can be formed from precursors bearing unsaturated side-chains in tandem cyclisations. An octahydroindolone has been converted to the ring skeleton of gamma-lycorane using samarium(II) iodide while reaction with manganese(III) acetate has been shown to yield a novel tetracyclic ring system bearing a 7-membered ring. Finally, a new tandem cyclisation of a cyclohexenone aryl halide has been shown to provide a quick approach to a 5,5,6,6-tetracycle related to erythrinane natural products. (C) 2000 Elsevier Science Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)7217-7228
Number of pages12
Issue number37
Publication statusPublished - 8 Sept 2000


  • radicals and radical reactions
  • cyclisation
  • alkaloids
  • enamides

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