RESUMO
Functional mimetics of the sialyl Lewis(X) tetrasaccharide were prepared by the enzymatic sialylation of a 1,3-diglycosylated indole and a glycosyl azide, which was subsequently transformed into a 1,4-diglycosylated 1,2,3-triazole, by using the trans-sialidase of Trypanosoma cruzi. These compounds inhibited the binding of E-, L-, and P-selectin-coated nanoparticles to polyacrylamide-bound sialyl-Lewis(X) -containing neighboring sulfated tyrosine residues (sTyr/sLe(X) -PAA) at low or sub-millimolar concentrations. Except for E-selectin, the mimetics showed higher activities than the natural tetrasaccharide.
Assuntos
Glicoproteínas/química , Mimetismo Molecular , Neuraminidase/química , Oligossacarídeos/química , Animais , Sequência de Carboidratos , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Dados de Sequência Molecular , Espectroscopia de Prótons por Ressonância Magnética , Selectinas/química , Antígeno Sialil Lewis X , Espectrometria de Massas por Ionização por Electrospray , Trypanosoma cruzi/enzimologiaRESUMO
The iodocyclization of o-alkynylbenzamides with various electrophiles has been reported to yield five- or six-membered lactams by nucleophilic attack of the amide nitrogen onto the triple bond. While the formation of an isobenzofuran-1(3H)-imine with two bulky substituents under Larock conditions was initially attributed to steric hindrance, we found out that cyclization via the amide oxygen is the rule rather than the exception. Thus, the structures of the products reported in the literature need to be revised.
RESUMO
Mono- and diglycosylated aromatics and heteroaromatics may serve as building blocks for the construction of metabolically stable mimetics of oligosaccharides. Methods for their preparation from monosaccharidic precursors by direct C-glycosylation, dipolar cycloaddition or Larock cyclization are described.
Assuntos
Hidrocarbonetos Aromáticos/química , Oligossacarídeos/química , Ciclização , Glicosilação , Hidrocarbonetos Aromáticos/síntese química , Oligossacarídeos/síntese químicaRESUMO
The crystal structure of the title compound, C(21)H(22)N(2)O(2)S, shows a network of N-Hâ¯N and N-Hâ¯O hydrogen bonds. The tolyl and 1-phenyl rings are almost mutually coplanar [7.89â (9)°], while the 2-phenyl ring makes a dihedral angle of 50.8â (1) ° with the 1-phenyl ring. An intra-molecular N-Hâ¯N hydrogen bond stabilizes the mol-ecular conformation.