Expedient Pyrrolizidine Synthesis by Propargylsilane Addition toN-Acyliminium Ions followed by Gold-Catalyzed α-Allenyl Amide Cyclization

Authors:
  • JDJan Dijkink
    Jan Dijkink
  • JMJan H. van Maarseveen
    Jan H. van Maarseveen
  • SKSape S. Kinderman
    Sape S. Kinderman
  • HHHenk Hiemstra
    Henk Hiemstra
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Abstract
A reaction sequence, involving the addition of (substituted) propargylsilanes to lactate-derived N-acyliminium ions followed by gold-catalyzed cyclization of the resulting alpha-allenyl amide, is applied in expedient syntheses of pyrrolizidine alkaloids heliotridine and ent-retronecine in five steps from (S)-malic acid