Unusual and Novel C11H16 Hydrocarbons from the Southern Australian Brown Alga Dictyopteris acrostichoides (Phaeophyceae)
✍ Scribed by Dieter Wirth; Iris Fischer-Lui; Wilhelm Boland; Detlef Icheln; Thorsten Runge; Wilfried A. König; Julie Phillips; Margaret Clayton
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- German
- Weight
- 765 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Unusual and novel C,,H,, olefins with (E)-or (E,E)-configuration instead of the previously known ( Z ) -or (E,Z)-configuration at the double bond(s) within the longer side chain are the main products of the Australian phaeophyte Dictyopteris acrostichoides. This configuration anomaly refers to all four series of alicyclic C , ,HI, hydrocarbons, namely the disubstituted cyclopentenes and cyclopropanes, as well as the monosubstituted cycloheptadienes and cyclopentenes. Chiral compounds within the above series have the same absolute configuration. The two (cyclopent-3-enyl)hexa-1,3-dienes 11 and 13 are found for the first time. The absolute configuration and optical purity of the hydrocarbons are determined by gas chromatography on modified cyclodextrins as chiral stationary phases. The synthesis of chiral references via lipase-catalyzed resolutions is described.
Introduction.
-The class of marine brown algae has evolved a unique pheromone system which to our present knowledge is almost exclusively based on a few series of simple acyclic, alicyclic, or aliheterocyclic C,,H,,, CIIH,,O, CllHI6, C,,H,,O, and C,,H,, olefins (cf. also Table ) [l] [2]. Freshly released male gametes of many phaeophytes respond chemotactically to the genuine pheromones at the lower nmolkpmol level. The signal molecules are biosynthesized from unsaturated fatty acids as was previously shown by in vivo feeding studies with the flowering plant Senecio isatideus as a model system [3]. In this terrestrial plant, (3Z,6Z,9Z)-dodeca-3,6,9-trienoic acid serves as the immediate precursor for several C,,H,, hydrocarbons among which ectocarpene (8) is by far the most abundant (94% of the total C,,H,, hydrocarbons). However, recent advances with female gametes of the two phaeophytes Ectocarpus siliculosus and Sphacelaria divaricata indicate that in the marine plants, the group of unsaturated C,, acids is replaced by the family of C,, polyenoic fatty acids like, e.g., icosatetraenoic, icosapentaenoic, and icosahexaenoic acid [4]. However, in contrast to the rather well understood biosynthesis of the C,, hydrocarbons in higher plants [3], nothing is known about the sequence of events of the algal metabolism leading from unsaturated C,, precursors to the C,, hydrocarbons. Since terrestrial plants lack the family of C,, polyenoic acids, at least for the present, the terrestrial model systems are no longer considered as being representative of the biosynthetic capacity of the enzymes from marine plants. To learn more about the various oxidation and degradation sites of, e.g., arachidonic acid in marine brown algae, we directed our attention further onto the search for new C,, structures. The large, cosmopolitan genus of Dictyopteris spp. is a well known and rich source of such hydrocarbons [5]. Another major advantage is the fact that in some Dictyopteris spp., the production of