1,721,052 research outputs found
SYNTHESIS AND AMINATION OF ALLYLSILANE ESTER DERIVATIVES
No full textLucio Pellacani, Maurizio D'Auria, Raffaele Saladin
Proline organocatalysis as a new tool for the asymmetric synthesis of ulosonic acid precursors
No full textPEP and aldolase mimicry is the key for a direct organocatalytic entry to precursors of ulosonic acids, biomolecules of enormous importance in biology, chemistry and medicine; in the key aldol reaction the dimethylacetal of pyruvic aldehyde is used as phosphoenolpyruvate (PEP) equivalent and the amino acid proline functions as an organocatalyst, imitating the enzym
Fatty acid hydroxytyrosyl esters: structure/antioxidant activity relationship by ABTS and in cell-culture DCF assays
No full textA large series of hydroxytyrosyl esters of C2-C18 fatty acids with increasing lipophilicity was prepared by acylation of methylorthoformate-protected hydroxytyrosol and tested for the relative antioxidant activity using ABTS assays in ethanolic medium and DCF assays on whole L6 cells. No correlation between lipophilicity and antioxidant activity was found. ABTS assays showed a growing activity, with respect to hydroxytyrosol, only for medium-sized ester chains (C4-C10), and a nearly constant activity for the higher homologues. A similar and dose-dependent pattern was observed in DCF assays on whole L6 cells, but a sharp activity drop resulted for long chain esters. Possible explanations are given
Reazione di Cross Coupling Pd Catalizzata per la Sintesi di [alpha-(trimethylsililmetil)iliden]-gamma-butirrolattoni
No full textAn Organocatalytic Approach to the Synthesis of Six-Membered Heterocycles
No full text"""In the last few years, the new era of organocatalysis opened up an effective and efficient way to high yielding metal free, enantio- and diastereoselective reactions leading to six-membered heterocycles. This review provides an overview of the current achievements in the organocatalytic synthesis of these crucial building blocks. Ranging from hetero-Diels-Alder to cycloadditions, from one step cyclizations to cascade reactions, recent results offer new powerful tools to obtain six membered heterocycles with facile procedures in high yields and stereoselection, often leading to many new stereogenic centres in a single reaction. The total syntheses of natural products having heterocyclic ring formation as crucial stage, are also reported. When available, alternative supported organocatalysts have been examined""
Fatty Acid Hydroxytyrosyl Esters: Structure/Antioxidant Activity Relationship by ABTS and in Cell-Culture DCF Assays
No full textA large series of hydroxytyrosyl esters of C2-C18 fatty acids with increasing lipophilicity was prepared by a new highly efficient method based on acylation of methylorthoformate-protected hydroxytyrosol. All products were tested for relative antioxidant effect using ABTS assays in ethanolic medium and DCF assays in L6 cells. No linear correlation between lipophilicity and antioxidant effect was found. ABTS assays showed a growing antioxidant capacity, with respect to hydroxytyrosol, only for medium-sized ester chains (C4-C10) and a nearly constant capacity for the higher homologues. This has been rationalized by molecular dynamics experiments in terms of partial shielding of the catecholic hydroxyls by long-chain esters. A similar and dose-dependent pattern was observed in DCF assays in L6 cells, but a sharp antioxidant activity drop resulted for long-chain esters, probably due to membrane entrapment
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