- Sesquiterpenes and phenolic compounds from achillea clypeolata
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The investigation of a dichloromethane extract of flower heads of Achillea clypeolata collected in Bulgaria led to the isolation of one guaiane (4,10,11-trihydroxy-guaiane, 1), four eudesmanes (4(15)-eudesmene-1β, 11-diol, 2, clypeotriol, 3, 3-epi-clypeotriol, 4, cryptomeridiol, 5), one diterpene (sugeroside, 6) and two phenolic compounds (centaureidin, 7 and scopoletin, 8). Their structures were elucidated by UV/vis, EI- and CI-MS as well as by one- and two-dimensional NMR experiments. 4,10,11-Trihydroxy-guaiane (1) and 3-epi-clypeotriol (4) are reported here for the first time.
- Werner, Ingrid,Mucaji, Pavel,Presser, Armin,Glasl, Sabine
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p. 267 - 271
(2008/03/13)
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- Chemical transformations of phyllocladane (=13β-kaurane) diterpenoids
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Earlier phytochemical work on Plectranthus ambiguus (Lamiaceae) afforded a series of tetracyclic phyllocladane-type (=13β-kaurane) diterpenoids (see 1a-f). In the course of investigations concerning the reaction behavior of this rare natural-products, a new constituent of P. ambiguus was isolated, (2S,3R,16R)-phyllocladane-2,3,16,17-tetrol 2,3-diacetate (1g), and another eighteen new phyllocladanes were prepared by chemical transformations and characterized. The main constituent 1b of P. ambiguus was chemically transformed to the known natural diterpenoid calliterpenone (=(16R)-16,17-dihydroxyphyllocladan-3-one; 2) thus unambiguously establishing its structure (Scheme 1). Epimerization at C(16) via the epoxy derivative 20 yielded 16-epicalliterpenone (21), 17-hydroxyphylloclad-15-ene-3-one (22), and (16R)-3-oxophyllocladan-17-al (23) (Scheme 6). Comparing this reaction sequence with the corresponding one starting from diastereoisomeric (16R)-16,17-dihydroxy-ent-kauran-3-one (=abbeokutone; 27) showed basically the same outcome (Scheme 7). Furthermore, three new C(16)-substituted ent-kauran-3-ones were characterized. Reliable spectroscopic arguments for the determination of the configuration at C(16) in phyllocladanes and kauranes as well as for the differentiation of the diastereoisomeric skeletons are presented.
- Liu, Gui,Mueller, Ralph,Rueedi, Peter
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p. 420 - 438
(2007/10/03)
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- GUAIANOLIDES AND HELIANGOLIDES FROM HYMENOPAPPUS NEWBERRYI
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The aerial parts of Hymenopappus newberryi afforded two heliangolides, two thymol derivatives, as well as two new guaianolides and a trans,trans-germacranolide closely related to hiyodorilactone A.Furthermore, the ent-kaurene derivative abbeokutone was present.These results are of chemotaxonomic interest.Key Word Index - Hymenopappus newberryi; Compositae; sesquiterpene; lactones; guaianolides; heliangolides; ent-kaurene derivative; chemotaxonomy.
- Bohlmann, F.,Zdero, C.,Turner, B. L.
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p. 1055 - 1058
(2007/10/02)
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