- Total synthesis of demethylwedelolactone and wedelolactone by Cu-mediated/Pd(0)-catalysis and oxidative-cyclization
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Hedysarimcoumestan B, which can be isolated from Chinese herbal medicine, is achieved, in which the longest linear sequence is only eight steps, in 50% overall yield from commercially available phloroglucinol. The key transformations in the synthesis are Cu-mediated/Pd(0)-catalysis and I2/pyridine oxidative-cyclization reactions. This synthetic strategy can be applied to give access to the demethylwedelolactone (4) and wedelolactone (5), which were afforded from commercially available phloroglucinol in high 38 and 33% yields, respectively.
- Chang, Chia-Fu,Yang, Ling-Yi,Chang, Shiao-Wei,Fang, Yu-Ting,Lee, Yean-Jang
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p. 3661 - 3666
(2008/09/20)
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- MUSHROOM TYROSINASE CATALYSED SYNTHESIS OF COUMENTANS, BENZOFURAN DERIVATIVES AND RELATED HETEROCYCLIC COMPOUNDS
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Full details of an improved synthesis of coumestan derivatives and their structural analogues, viz., wedelolactone, 11-hydroxy aureol, 11-hydroxy coumestrol along benzofuran derivatives and related heterocyclic systems are reported by coupling of in situ generated o-quinones from catechols catalysed by mushroom tyrosinase with various reatants.
- Pandey, G.,Muralikrishna, C.,Bhalerao, U. T.
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p. 6867 - 6874
(2007/10/02)
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- Wedelolactone and coumestan derivatives as new antihepatotoxic and antiphlogistic principles
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For the study of structure-activity relationships, the antihepatotoxic wedelolactone (7-methoxy-5,11,12-trihydroxy-coumestan) and 6 coumestan derivatives were synthesized by the application of a modified method of Wanzlich. An evaluation of the biological characteristics of the synthetic compounds and acuminatin from Musa acuminata showed that most of the wedelolactone derivatives significantly protected primary cultured liver cells from the toxicity of CCl4, galactosamine (Galc), and phalloidin, and strongly inhibited the activity of 5-lipoxygenase in porcine leukocytes. The hepatocyte protective activity was dependent on the C-7 substitution with pharmacological efficacy decreasing in the following order: EtO > MeO > OH > CH3(CH2)9. In addition, a free OH at C-5 of the wedelolactone molecule was shown to be important in protecting hepatocytes from CCl4 and Galc damage. Similar observation regarding the effect of C-7 substitution in wedelolactone was obtained in the 5-lipoxygenase test. In general, an increase in the lipophilicity in ring A increased the inhibition of 5-lipoxygenase activity. The synthetic wedelolactone was also found to have stimulatory effect on the RNA synthesis in isolated nuclei from hepatocytes.
- Wong,Antus,Gottsegen,Fessler,Rao,Sonnenbichler,Wagner
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p. 661 - 665
(2007/10/02)
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- Synthesis of Oxygenated Coumestans
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Eight oxygenated coumestans and their acetates have been prepared by dehydrative cyclisation of 4-hydroxy-3-arylcoumarins using methanolic hydrogen chloride.Their spectral characteristics and useful physiological properties have been presented.
- Rani, B. S. Uma,Darbarwar, Malleshwar
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p. 1060 - 1062
(2007/10/02)
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- Electrochemical Synthesis of Heterocyclic Compounds. XII. Anodic Oxidation of Catechol in the Presence of Nucleophiles
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The electrochemical synthesis of coumestan derivatives and some related heterocyclic system (2a-11a) by anodic oxidation of catechol (1) in the presence of various nucleophiles 2-11 is described.Products were obtained in good yields and purity.The mechanism of oxidation was deduced from voltammetric data and by coulometry at controlled potential.
- Tabakovic, Ibro,Grujic, Zdravko,Bejtovic, Zlatko
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p. 635 - 638
(2007/10/02)
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