title: Identification, synthesis and mass spectrometry of a macrolide from the African reed frogHyperolius cinnamomeoventris.
abstract: The contents of the gular glands of the male African reed frogHyperolius cinnamomeoventrisconsist of a mixture of aliphatic macrolides and sesquiterpenes. While the known macrolide gephyromantolide A was readily identified, the structure of another major component was suggested to be a tetradecen-13-olide. The synthesis of the two candidate compounds (Z)-5- and (Z)-9-tetradecen-13-olide revealed the former to be the naturally occurring compound. The synthesis used ring-closing metathesis as key step. While the Hoveyda-Grubbs catalyst furnished a broad range of isomeric products, the (Z)-selective Grubbs catalyst lead to pure (Z)-products. Analysis by chiral GC revealed the natural frog compound to be (5Z,13S)-5-tetradecen-13-olide (1). This compound is also present in the secretion of other hyperoliid frogs as well as in femoral glands of male mantellid frogs such asSpinomantis aglavei. The mass spectra of the synthesized macrolides as well as their rearranged isomers obtained during ring-closing metathesis showed that it is possible to assign the location of the double bond in an unsaturated macrolide on the basis of its EI mass spectrum. The occurrence of characteristic ions can be explained by the fragmentation pathway proposed in the article. In contrast, the localization of a double bond in many aliphatic open-chain compounds like alkenes, alcohols or acetates, important structural classes of pheromones, is usually not possible from an EI mass spectrum. In the article, we present the synthesis and for the first time elucidate the structure of macrolides from the frog family Hyperoliidae.
authors.affiliation: Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Menke
authors.affiliation: Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.
authors.forename: Pardha Saradhi
authors.initials: PS
authors.lastname: Peram
authors.affiliation: Department for Integrative Zoology, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Iris
authors.initials: I
authors.lastname: Starnberger
authors.affiliation: Department for Integrative Zoology, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Hödl
authors.affiliation: Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, United States of America.
authors.forename: Gregory Fm
authors.initials: GF
authors.lastname: Jongsma
authors.affiliation: Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, United States of America.
authors.forename: David C
authors.initials: DC
authors.lastname: Blackburn
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115 Berlin, Germany.
authors.forename: Mark-Oliver
authors.initials: MO
authors.lastname: Rödel
authors.affiliation: Technische Universität Braunschweig, Institute of Zoology, 38106 Braunschweig, Germany.
authors.forename: Miguel
authors.initials: M
authors.lastname: Vences
authors.affiliation: Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
keywords: chemical communication; chiral gas chromatography; macrocyclic lactones; pheromones; ring-closing metathesis