1,721,236 research outputs found
Asymmetric synthesis of 3-methyl-2-phenyl-1,4-benzodioxanes. Absolute configuration of the neolignans eusiderin and eusiderin C and D
No full textThe asymmetric synthesis of 2S,3S- and 2R,3S-3-methyl-2-phenyl-1,4- benzodioxane from (-)-ephedrine is reported. Comparison of the c.d. curves of these compounds with those of the natural neolignans eusiderin and eusiderin C allows the assignment of 2R,3R configuration to eusiderin and of 2R,3S configuration to eusiderin C and eusiderin D
A new synthesis of the cytotoxic alkaloid Luotonine A
No full textA convenient synthesis of the cytotoxic alkaloid Luotonine A has been achieved using cheap and readily accessible reagents. The key intermediate in the synthesis is the tricyclic compound 2,3-dihydro[1H]-pyrrolo[3,4-b]quinolin-3-one (5)
Lipophilicity-antifungal activity relationships for some isoflavonoid phytoalexins
No full textThe octanol/water partition coefficients of 18 isoflavonoid phytoalexins have been determined by reversed-phase HPLC and/or calculated by the use of Hansch hydrophobic parameters: The values obtained are in the range 1.5-4.2. From a study of the relationship between these data and the antifungal activity on Aphanomyces euteiches and Fusarium solani f.sp. cucurbitae reported by Van Etten, it appears that within groups of compounds of similar structure an increase in lipophilicity correlates positively with increased antifungal activity, whereas a general correlation for the whole class of isoflavonoid phytoalexins was not found. On the other hand, correlations with some other structural factors, such as the presence of a phenolic OH or benzylic hydrogen atoms, seem possible
Progress in isovanillyl sweet compounds
No full textThe so-called isovanillyl sweeteners are organic compounds containing the 3-hydroxy-4-methoxyphenyl moiety, which seems to be essential for the sweet taste of these compounds. Most of them are heterocyclic compounds, with a free rotating isovanillyl group and one chiral carbon atom. Rigid compounds with structures mimicking some of the possible preferred conformations which can be assumed by the isovanillyl sweeteners were prepared and tasted. To establish possible correlations between chirality and taste, the enantioselective synthesis of the (-)-enantiomer of the natural sweet compound (+)-hematoxylin was performed. The sweetest among the isovanillyl compounds was modified by introducing groups apt to interact with the D site of the Nofre-Tinti receptor model. All the results are discussed on the basis of comparison with the most recent models for the sweet taste receptor
Reazione intramolecolare di Friedel-Crafts di indoli con gruppi carbonilici : una semplice sintesi di b-carbolin-1-oni e di diidro-2H-azepino[3,4-b]indol-1-oni
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