- GUAIANE SESQUITERPENES FROM MAGNOLIA WATSONII
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The leaves and the trunk barks of Magnolia watsonii afforded two biosynthetic intermediates of dehydrocostuslactone (watsonol A and watsonol B) along with the neolignans, magnolol, honokiol and obovatol, and the aporphine alkaloids, liriodenine and asimilobine.Key Word Index - Magnolia watsonii; Magnoliaceae; sesquiterpenes; dehydrocostuslactone; watsonol A; watsonol B; 15-acetoxycostunolide; neolignans; obovatol; aporphine alkaloids.
- Ito, Kazuo,Iida, Toshiyuki,Kobayashi, Toshiro
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- Asymmetric Total Synthesis of (?)-Dehydrocostus Lactone by Domino Metathesis
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An efficient total synthesis of the sesquiterpenoid (?)-dehydrocostus lactone is reported. Our earlier approach by a domino enediyne metathesis was extended by a domino dienyne metathesis strategy to give access to suitably functionalized hydroazulene cores. Highly stereoselective asymmetric anti aldol reactions provided the enantiopure substrates for this key step of our synthesis. Multiple hydroboration/oxidation of the resulting hydroazulenes set up three out of four stereogenic centers in a single step. First, oxidation to give a diketo-γ-lactone enabled an enantioselective formal synthesis of the target guaianolide. Subsequently, the final steps of this approach were improved by using a double carbonyl olefination at the stage of a masked γ-butyrolactone, which completed the synthesis in a much more efficient way.
- Barthel, André,H?fner, Franziska,Hennersdorf, Felix,J?ger, Anne,Kaden, Felix,Lorenz, Melanie,Metz, Peter,Nowotni, Susanne,Weigand, Jan J.
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p. 3579 - 3586
(2021/07/22)
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- Enantioselective Total Synthesis of the Guaianolide (-)-Dehydrocostus Lactone by Enediyne Metathesis
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The hydroazulene core of the bioactive sesquiterpenoid (-)-dehydrocostus lactone was generated by domino enediyne metathesis. A triple hydroboration/oxidation of the resultant conjugated triene installed three out of four stereogenic centers of the target in a single step. The enantiopure acyclic metathesis substrate was readily available by an asymmetric anti aldol reaction. Masking of the O-lactone as an acetal allowed for an efficient completion of the synthesis through late-stage double carbonyl olefination.
- Kaden, Felix,Metz, Peter
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supporting information
p. 1344 - 1348
(2021/02/20)
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- Absolute stereostructures and syntheses of saussureamines A, B, C, D and E, amino acid-sesquiterpene conjugates with gastroprotective effect, from the roots of Saussurea lappa
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From the methanolic extract of the dried roots of Saussurea lappa Clarke, Saussureae Radix, five amino acid-sesquiterpene conjugates, saussureamines A, B, C, D and E, were isolated together with a lignan glycoside, (-)-massoniresinol 4-O-β-D-glucopyranoside. Their stereostructures were determined on the basis of chemical and physicochemical evidence. In addition, saussureamines and the related amino acid-sesquiterpene conjugates were synthesized using a Michael type addition reaction of amino acid to the α-methylene-γ-lactone moiety of sesquiterpenes. Saussureamines A, B and C, costunolide and dehydrocostus lactone showed a gastroprotective effect on acidified ethanol-induced gastric mucosal lesions in rats. Saussureamines A also exhibited an inhibitory effect on gastric mucosal lesions induced by water-immersion stress in mice. (C) 2000 Elsevier Science Ltd.
- Matsuda, Hisashi,Kageura, Tadashi,Inoue, Yasunao,Morikawa, Toshio,Yoshikawa, Masayuki
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p. 7763 - 7777
(2007/10/03)
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- Guaianolides as immunomodulators. Synthesis and biological activities of dehydrocostus lactone, mokko lactone, eremanthin, and their derivatives
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The naturally occurring guaianolides, namely mokko lactone (1), dehydrocostus lactone (2), eremanthin (3), and related guaianolides, 16, 17, 21, 22, 28-31, 33, 36, 37, and 39, have been synthesized starting from l-α- santonin in an effort to examine their structure-activity relationship as inhibitors of the killing function of cytotoxic T lymphocytes (CTL) and the induction of intercellular adhesion molecule-1 (ICAM-1). It was observed during the present study that the guaianolides possessing an α-methylene γ- lactone moiety, i.e., 2, 3, 30, 33, 37, and 39, exhibited significant inhibitory activity toward the killing function of CTL and the induction of ICAM-1.
- Yuuya, Saori,Hagiwara, Hisahiro,Suzuki, Toshio,Ando, Masayoshi,Yamada, Atsushi,Suda, Kouji,Kataoka, Takao,Nagai, Kazuo
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- TOTAL SYNTHESES OF MOKKO LACTONE, DEHYDROCOSTUS LACTONE, AND EREMANTHIN
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A series of guaianolides such as mokko lactone, dehydrocostus lactone, and eremanthin which posses a common structural unit in A ring have been synthesized from 1-oxoeudesm-2-eno-13,6α-lactone in 7 steps.The key step involves solvolytic rearrangement of 1β-mesyloxyeudesm-4(14)-eno-13,6α-lactone.
- Ando, Masayoshi,Ono, Akio,Takase, Kahei
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p. 493 - 496
(2007/10/02)
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