Ferrier glycosylation for synthesis of O- and S-glycopeptides

Abstract

Ferrier glycosylation could be employed for the syntheses of a range of unsaturated O- as well as S-glycopeptides. Thus, featuring high yields and in many cases convincing diastereomeric excesses, an efficient protocol for formation of this class of compounds was established.     

Influence of Charge Density of Anionic Polyelectrolytes on Structure Formation in Liquid Crystalline Systems

The influence of different amounts of anionic copolymers of N-Methyl N-vinyl acetamide (NMVA) and acrylic acid with various charge densities on the formation of the lamellar liquid crystal formed by sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of polarization microscopy, small angle x-ray scattering (SAXS), transmission electron microscopy and rheology. On the contrary to the incorporation of poly(acrylic acid)     

Silver Zeolite as Promoter in Glycoside Synthesis. The Synthesis of 2-Deoxy-β-D-Glycopyranosides

The use of silver zeolite as a promoter for the preparation of β-linked 2-deoxygtycosides and disaccharides of biological relevance has been explored. Starting from benzoylated glycosyl bromides, the total yield of glycosides varies from 54 to 84% and the α:β ratio from 0.25 to 1.18.     

2-Phosphinophenolate complexes: formation and crystal structure of a novel trinuclear mu-O nickel(II)-tris(P(intersection)O-chelate)

A novel linear trinuclear mu-O-bridging 2-phosphinophenolate nickel(II) complex with fac-tris(P(intersection)O- chelates) in the terminal positions and the three oxygen atoms each facing the central nickel(II) cation was synthesized and structurally characterized by X-ray crystallography. To the best of our knowledge, this is the first example of an octahedral Ni(II) tris(P(intersection)O- chelate).     

Fluorescence study of the sol-gel process in hybrid precursors: evidence of concentration fluctuations at the local scale

Hybrid sol-gel materials have been prepared by hydrolytic polycondensation of an alkoxysilane. The sol-gel process of methacryloxypropyltrimethoxysilane (MAPTMS) has been followed by fluorescence spectroscopy with 2-naphthol as a probe. The experimental results showed that this photoprobe was dramatically sensitive to the microenvironment polarity. Spectroscopic studies revealed fluctuations of the maximum emission intensity and wavelength as a function of time. These fluctuations were attributed to the amphiphilic behavior of the hydrolyzed precursor. The maximum emission wavelength of the probe corresponding to its protonated form was higher than in pure water. All the results suggest that the presence of water molecules, tightly bonded to the polar head of the silanols, increased locally the sol polarity and induced a red-shifted emission. Fluorescence spectroscopy emphasized the reversibility of monomeric silanol aggregates and the changes in hydroxy group number of the silica network during the sol maturation. The behavior of this system upon shaking confirmed this statement.     

Formation of LacNAc mimetics employing novel donor substrates for enzymatic beta 1-->4 galactosylation

In examining C-6 modified 4-nitrophenyl beta-D-galactopyranosides as donor structures the beta-galactosidase (Bacillus circulans) revealed an unexpectedly broad substrate specificity which allowed successful syntheses of various disaccharide components.