Total synthesis of (+)-seco-C-oleanane via stepwise controlled radical cascade cyclization

J Org Chem. 2012 Jan 6;77(1):341-50. doi: 10.1021/jo201968t. Epub 2011 Dec 16.

Abstract

An asymmetric concise total synthesis of the (+)-seco-C-oleanane 1 was accomplished. The successful route to this natural product involves as the key step a stepwise regio- and stereocontrolled catalytic radical polyene cascade cyclization from preoleanatetraene oxide (16), a process mediated by Cp(2)TiCl. The use of this single-electron-transfer complex permits mild cyclization conditions without using unnecessary prefunctionalizations and stops the process at the bicyclic level. Theoretical data revealed high activation energy for the third ring closure, which would account for the control of the cyclization. This process also led to natural (-)-achilleol B, camelliol A, and (+)-seco-β-amyrin as minor compounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Products / chemical synthesis*
  • Biological Products / chemistry
  • Catalysis
  • Cyclization
  • Molecular Structure
  • Oleanolic Acid / analogs & derivatives*
  • Oleanolic Acid / chemical synthesis
  • Oleanolic Acid / chemistry*
  • Quantum Theory
  • Stereoisomerism
  • Triterpenes / chemical synthesis*
  • Triterpenes / chemistry

Substances

  • Biological Products
  • Triterpenes
  • achilleol B
  • oleanane
  • Oleanolic Acid
  • beta-amyrin