ABSTRACT
Nucleophilic enamines add spontaneously on heteroarenes 3-nitroindole and benzofuran to form a new C-C bond. With nitroindole and enamine , an unprecedented dearomatizing formal ene reaction occurs in a totally regio- and diastereo-selective manner. With 3-nitrobenzofuran and enamine , the reaction course is different and leads to the generation of a dienylphenol.
ABSTRACT
A novel Ni(0) -catalyzed carboxylation of aryl tosylates with carbon dioxide has been achieved under moderate temperatures and atmospheric pressure. In this procedure, the active Ni(0) species is generated in situ by simply mixing the Ni(0) precatalyst [NiBr2 (bipy)] with an excess of manganese metal. This approach requires neither a glove-box nor the tedious preparation of sophisticated intermediate organometallic derivatives. This mild, convenient, and user-friendly process is successfully applied to the valorization of carbon dioxide and the synthesis of versatile reactants with broad tolerance of substituents.
ABSTRACT
DC-SIGN and Langerin are two C-type lectins involved in the initial steps of HIV infections: the former acts as a viral attachment factor and facilitates viral invasion of the immune system, the latter has a protective effect. Potential antiviral compounds targeted against DC-SIGN were synthesized using a common fucosylamide anchor. Their DC-SIGN affinity was tested by SPR and found to be similar to that of the natural ligand Lewis-X (Le(X)). The compounds were also found to be selective for DC-SIGN and to interact only weakly with Langerin. These molecules are potentially useful therapeutic tools against sexually transmitted HIV infection.
Subject(s)
Cell Adhesion Molecules/antagonists & inhibitors , Cell Adhesion Molecules/metabolism , Fucose/chemistry , Fucose/pharmacology , Lectins, C-Type/antagonists & inhibitors , Lectins, C-Type/metabolism , Receptors, Cell Surface/antagonists & inhibitors , Receptors, Cell Surface/metabolism , Anti-HIV Agents/chemistry , Anti-HIV Agents/pharmacology , Antigens, CD/metabolism , HIV Infections/drug therapy , Humans , Mannose-Binding Lectins/metabolism , Models, Molecular , Protein BindingABSTRACT
The adhesion of bacteria to human glycoconjugates can be inhibited by soluble glycomimetics that compete with the natural target. Four monovalent and one divalent alpha-fucosyl amides have been tested for their affinity for a fucose-binding lectin from Pseudomonas aeruginosa. Isothermal calorimetric titrations demonstrated that they bind to the lectin in the micromolar range, with highest affinity for the divalent ligand. Molecular modelling established that, compared to Omicron-fucoside compounds, the glycomimetic amide group resulted in the loss of water-bridged hydrogen bonds that could be partially compensated by additional contact of the aglycone with the protein surface.
Subject(s)
Adhesins, Bacterial/metabolism , Amides/chemistry , Fucose/chemistry , Fucose/metabolism , Lectins/metabolism , Pseudomonas aeruginosa , Adhesins, Bacterial/chemistry , Glycosylation , Lectins/chemistry , Ligands , Models, Molecular , Protein Binding , Protein ConformationABSTRACT
The synthesis and solution conformation of homo-oligomers of beta-aminoacids, beta-N-mannofuranosyl-3-ulosonic acids, have been studied by NMR, MD simulation, and circular dichroism. These oligomers feature a spirocyclic disubstitution and a N,O-acetal functionality at the beta-carbon of the backbone, an unprecedented situation in the realm of beta-peptides. Our study shows that tetramer 10 and hexamer 11 adopt a characteristic secondary structure. In the hexamer 11, NMR investigations coupled with MD simulations suggest the preference for a double C(8) turn forming conformation.
