- A multiproduct terpene synthase from medicago truncatula generates cadalane sesquiterpenes via two different mechanisms
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Terpene synthases are responsible for a large diversity of terpene carbon skeletons found in nature. The multiproduct sesquiterpene synthase MtTPS5 isolated from Medicago truncatula produces 27 products from farnesyl diphosphate (1, FDP). In this paper, we report the reaction steps involved in the formation of these products using incubation experiments with deuterium-containing substrates; we determined the absolute configuration of individual products to establish the stereochemical course of the reaction cascade and the initial conformation of the cycling substrate. Additional labeling experiments conducted with deuterium oxide showed that cadalane sesquiterpenes are mainly produced via the protonation of the neutral intermediate germacrene D (5). These findings provide an alternative route to the general accepted pathway via nerolidyl diphosphate (2, NDP) en route to sesquiterpenes with a cadalane skeleton. Mutational analysis of the enzyme demonstrated that a tyrosine residue is important for the protonation process.
- Garms, Stefan,Koellner, Tobias G.,Boland, Wilhelm
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supporting information; experimental part
p. 5590 - 5600
(2010/11/20)
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- The synthesis of mono- and dihydroxy aromadendrane sesquiterpenes, starting from natural (+)-aromadendrene-III
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The monoalcohols (-)-globulol (2), (-)-epiglobulol (3), (-)-ledol (4), and (+)-viridiflorol (5) were synthesized from (+)-aromadendrene (1). The cis-fused alloaromandedrone (14), the key intermediate used in the synthesis of 4 and 5, was obtained from the trans-fused apoaromadendrone (13) via a selective protonation of the thermodynamic enol trimethylsilylether 15. After hydroxylation of the tertiary C11 of 13 with RuO4, (+)-spathulenol (6), (-)-allospathulenol (7), and the aromadendrane diols 8-11 could be prepared. Compounds 2-11 were tested for antifungal properties, but their activity was only moderate.
- Gijsen, Harrie J. M.,Wijnberg, Joannes B. P. A.,Stork, Gerrit A.,De Groot, Aede,De Waard, Maarten A.,Van Nistelrooy, Johannes G. M.
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p. 2465 - 2476
(2007/10/02)
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- The conversion of natural (+)-aromadendrene into chiral synthons-I
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(-)-Apoaromadendrone (3) can be obtained easily in large quantities from (+)-aromadendrene which is the main constituent in a commercially available distillation tail of the oil of Eucalyptus globules. Acid catalyzed selective cleavage of the C3-C4 bond of the cyclopropane ring in 3 gave (-)-isoapoaromadendrone(9) in high yield. The regioselectivity of the cyclopropane ring opening was proved by NMR spectroscopy in combination with chemical transformations. Ozonolysis of 9 afforded the keto alcohol 14 which is a suitable chiral intermediate for the syntheses of guaianes and guaianolides.
- Gijsen, Henricus J. M.,Kanai, Karoly,Stork, Gerrit A.,Wijnberg, Joannes B.P.A.,Orru, Romano V. A.,Seelen, Claudy G. J. M.,Van Der Kerk, Sies M.,De Groot, Aede
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p. 7237 - 7246
(2007/10/02)
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