A second generation formal synthesis of (-)-cephalotaxine

J Org Chem. 2008 Oct 17;73(20):8045-8. doi: 10.1021/jo801540q. Epub 2008 Sep 12.

Abstract

A second generation formal synthesis of the alkaloid (-)-cephalotaxine has been achieved using an alkylidene carbene 1,5-CH insertion reaction to establish a key quaternary stereocenter. The carbene precursor was readily derived from L-proline, and the 1,5-CH insertion reaction was performed under Ohira's conditions using lithiotrimethylsilyldiazomethane (LTDM), which gave the desired spirocyclic product in 74% yield. The hydroxymethyl group was then oxidized and then decarbonylated (93%), and this material was easily transformed into the desired Friedel-Crafts cyclization precursor. Exposure of this material to SnCl4 then gave the desired pentacyclic product, which was identical to that previously prepared by Mori and thus represents a formal total synthesis of (-)-cephalotaxine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diazomethane / analogs & derivatives
  • Diazomethane / chemistry
  • Harringtonines / chemical synthesis*
  • Homoharringtonine
  • Methane / analogs & derivatives
  • Methane / chemistry
  • Proline / chemistry
  • Stereoisomerism
  • Tin Compounds / chemistry
  • Trimethylsilyl Compounds / chemistry

Substances

  • (trimethylsilyl)diazaomethane
  • Harringtonines
  • Tin Compounds
  • Trimethylsilyl Compounds
  • carbene
  • Diazomethane
  • stannic chloride
  • Homoharringtonine
  • Proline
  • Methane