The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products

Proc Natl Acad Sci U S A. 2009 Jun 2;106(22):8877-82. doi: 10.1073/pnas.0900646106. Epub 2009 May 21.


Orchids employing sexual deceit attract males of their pollinator species through specific volatile signals that mimic female-released sex pheromones. One of these signals proved to be 2-ethyl-5-propylcyclohexan-1,3-dione (chiloglottone1), a new natural product that was shown to be most important in the relations between orchids of the genus Chiloglottis, native to Australia, and corresponding pollinator species. Systematic investigations on the mass spectrometric fragmentation pattern of 2,5-dialkylcyclohexan-1,3-diones identified key ions providing information about the structures of the substituents at positions 2 and 5. Results enabled us to identify 2-ethyl-5-pentylcyclohexan-1,3-dione (chiloglottone2) and 2-butyl-5-methylcyclohexan-1,3-dione (chiloglottone3) as new natural products that play a decisive role in the pollination syndrome of some Chiloglottis species. During field bioassays, pure synthetic samples of chiloglottone1-3 or mixtures thereof proved to be attractive to the corresponding orchid pollinators. Because of their likely biogenesis from ubiquitous fatty acid precursors, 2,5-dialkylcyclohexan-1,3-diones may represent a hitherto overlooked, widespread class of natural products.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Products / chemistry*
  • Biological Products / metabolism
  • Cyclohexanones / chemistry*
  • Cyclohexanones / metabolism
  • Magnetic Resonance Spectroscopy
  • Orchidaceae / chemistry*
  • Orchidaceae / metabolism
  • Sex Attractants / chemistry*
  • Sex Attractants / metabolism


  • 2-butyl-5-methylcyclohexan-1,3-dione
  • 2-ethyl-5-pentylcyclohexan-1,3-dione
  • 2-ethyl-5-propylcyclohexan-1,3-dione
  • Biological Products
  • Cyclohexanones
  • Sex Attractants