Total synthesis of graphislactones A, C, D, and H, of ulocladol, and of the originally proposed and revised structures of graphislactones e and F

Martina Altemöller, Timo Gehring, Judith Cudaj, Joachim Podlech*, Helmut Goesmann, Claus Feldmann, Alexander Rothenberger

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Graphislactones A-H and the structurally related ulocladol are highly oxygenated resorcylic lactones produced by lichens and fungi. We present total syntheses of graphislactones A, C-F, H and of ulocladol. Graphislactones E, F, and H were synthesized for the first time. The spectra of graphislactones E and F synthesized as the originally proposed structures were not in agreement with published data. Consequently, revised structures for these compounds are proposed, whose correctness is unambiguously proven by total synthesis and comparison of the spectroscopic data. Key steps in all syntheses are Suzuki couplings for the construction of the central biaryl bond and Dakin reactions to supply further hydroxy groups required in these highly oxygenated substrates. Graphislactones A, C, and H, acylated graphislac- tone D and ulocladol were prepared in 8-11 steps with 7-20% yield starting with purchasable compounds, where the longest linear sequence consists of 5-9 steps. The syntheses are thus significantly shorter than the previously published syntheses of graphislactones A-D and of ulocladol. Graphis- lactones E and F were synthesized in 8 steps, where the longest linear sequences consist of 6 and 5 steps, respectively. They were isolated as the respective acetylated compounds with 25 and 10% yield.

Original languageEnglish (US)
Pages (from-to)2130-2140
Number of pages11
JournalEuropean Journal of Organic Chemistry
Issue number13
DOIs
StatePublished - May 2009
Externally publishedYes

Keywords

  • Cross-coupling
  • Dakin reaction
  • Lichen metabolites
  • Polyketides
  • Resorcylic lactones
  • Total synthesis

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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