Enantioselective Total Syntheses of the Cephalotaxus Alkaloids (-)-Fortuneicyclidins A and B and (-)-Cephalotine B

Org Lett. 2023 Oct 20;25(41):7464-7469. doi: 10.1021/acs.orglett.3c02739. Epub 2023 Oct 6.

Abstract

Fortuneicyclidins A and B are a pair of recently isolated Cephalotaxus alkaloids with an unprecedented rearranged polycyclic skeleton possessing multiple complex stereocenters and functionalization. In this work, highly stereocontrolled asymmetric total syntheses for title alkaloids were outlined. Key features include an underexplored Ir-catalyzed α-allylation of aldehyde to strategically install a vicinal N-substituted quaternary center and a tertiary stereocenter, Heck and RCM reactions to construct the critical polycyclic framework rapidly, two different tandem oxidation-transannular aldol cyclization processes, one through ozonolysis and another via Swern oxidation, to forge the last ring for fortuneicyclidins A and B, respectively. In this approach, the challenging C-2 hydroxyl group can be installed stereospecifically.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaloids*
  • Cyclization
  • Harringtonines*
  • Oxidation-Reduction
  • Stereoisomerism

Substances

  • Harringtonines
  • Alkaloids