Concise total syntheses of the bioactive mesotricyclic diterpenoids jatrophatrione and citlalitrione

J Am Chem Soc. 2003 Feb 12;125(6):1567-74. doi: 10.1021/ja021177r.

Abstract

The highly functionalized [5.9.5] tricyclic framework resident in jatrophatrione (1) and citlalitrione (2) has been synthesized. The route begins with the tandem anionic oxy-Cope rearrangement/methylation/transannular ene cyclization of 21 and subsequent introduction of a conjugated enone double bond. Hydroxyl-directed 1,4-reduction of this functionality in 25 with LiAlH(4)/CuI/hexamethylphosphoramide/tetrahydrofuran sets the stage for the implementation of a Grob fragmentation and expedited generation of 27. Stereocontrolled intramolecular hydrosilylation allows for the subsequent introduction of a cyclic carbonate as in 53. This intermediate undergoes remarkably efficient, fully regiocontrolled Treibs reaction to generate 54, with this maneuver serving as a pivotal step for making 1 available five steps later. Treatment of 1 with m-chloroperbenzoic acid leads to 2, with attack occurring preferentially on a alpha-face of the double bond more remote to the carbonyl.

MeSH terms

  • Antineoplastic Agents, Phytogenic / chemical synthesis*
  • Diterpenes / chemical synthesis*
  • Jatropha / chemistry

Substances

  • Antineoplastic Agents, Phytogenic
  • Diterpenes
  • citlalitrione
  • jatrophatrione