Total synthesis of the monoterpenoid alkaloid (±)-tangutorine

Org Biomol Chem. 2012 Feb 7;10(5):945-51. doi: 10.1039/c1ob06539d. Epub 2011 Dec 1.

Abstract

A novel approach to a formal total synthesis of the monoterpenoid indole alkaloid (±)-tangutorine has been developed starting from an α,β-unsaturated cyclic dehydroamino ester. Synthesis of the rather unusual trans-substituted 2,3-indoloquinolizidine substructure was accomplished via Cu(II)-mediated conjugate addition and organozinc/copper coupling as the key steps, thereby setting the stage for ring-closing metathesis to produce the quinolone substructure. Finally, Bischler-Napieralski cyclization gave rise to the pentacyclic system of (±)-tangutorine thereby realizing a formal synthesis in an overall yield of 5.2% in eight consecutive steps.

MeSH terms

  • Alkaloids / chemical synthesis*
  • Carbolines / chemical synthesis*
  • Copper / chemistry
  • Cyclization
  • Monoterpenes / chemical synthesis*
  • Quinolizines / chemical synthesis*
  • Stereoisomerism

Substances

  • Alkaloids
  • Carbolines
  • Monoterpenes
  • Quinolizines
  • tangutorine
  • Copper