Concise Total Syntheses of the Bioactive Mesotricyclic Diterpenoids Jatrophatrione and Citlalitrione

Jiong Yang, Yun Oliver Long, and Leo A. Paquette*
Contribution from the Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210
J. Am. Chem. Soc., 2003, 125 (6), pp 1567–1574
DOI: 10.1021/ja021177r
Publication Date (Web): January 11, 2003
Copyright © 2003 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, paquette.1@osu.edu

Abstract

Abstract Image

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 LiAlH4/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 α-face of the double bond more remote to the carbonyl.

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History

  • Published In Issue February 12, 2003
  • Received September 12, 2002

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