title: The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products.
abstract: 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.
authors.affiliation: Department of Chemistry, Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Franke
authors.forename: F
authors.initials: F
authors.lastname: Ibarra
authors.forename: C M
authors.initials: CM
authors.lastname: Schulz
authors.forename: R
authors.initials: R
authors.lastname: Twele
authors.forename: J
authors.initials: J
authors.lastname: Poldy
authors.forename: R A
authors.initials: RA
authors.lastname: Barrow
authors.forename: R
authors.initials: R
authors.lastname: Peakall
authors.forename: F P
authors.initials: FP
authors.lastname: Schiestl
authors.forename: W
authors.initials: W
authors.lastname: Francke
mesh_terms: D001688:Biological Products / Q000737:chemistry* / Q000378:metabolism; D003512:Cyclohexanones / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D029595:Orchidaceae / Q000737:chemistry* / Q000378:metabolism; D012724:Sex Attractants / Q000737:chemistry* / Q000378:metabolism
chemical_list: C541332:2-butyl-5-methylcyclohexan-1,3-dione; C541331:2-ethyl-5-pentylcyclohexan-1,3-dione; C478538:2-ethyl-5-propylcyclohexan-1,3-dione; D001688:Biological Products; D003512:Cyclohexanones; D012724:Sex Attractants