Ligand- and metal-exchange reactions of robust nickel complexes with pentagonal bipyramidal structures.

The coordination chemistries of transition metal complexes with pentagonal bipyramidal geometries were investigated, and the highly stable nature of a cyclic pentapyridyl ligand was disclosed. A NiCl complex with the pentapyridyl ligand was found to be stable toward water and acidic conditions. The stable complex underwent ligand-exchange reactions with nucleophilic reagents, and a series of pentagonal bipyramidal complexes with different apical ligands was prepared.

Multivalent galacto-trehaloses: design, synthesis, and biological evaluation under the concept of carbohydrate modules.

Galacto-trehalose (GT) is a novel class of 1,1'-linked nonreducing disaccharide having an α-galactoside epitope. In this study, a pair of α,α- and α,β-GT isomers were prepared in one pot with our α-glycosylation method, converted into vinyl monomers and then subjected to radical copolymerization with a second sugar (4-acrylamidophemyl β-Glc or β-GlcNAc) in the presence of acrylamide. The derived glycopolymers were assayed with α-galactoside-specific proteins (BSI-B(4) lectin and Shiga toxin-1) to show the results that both α,α- and α,β-isomers are recognized by these carbohydrate-binding proteins more strongly in forms of the GT polymers.

Synthesis and absolute structures of Mycoplasma pneumoniae beta-glyceroglycolipid antigens.

Just recently, a pair of beta-glycolipids was isolated from the cell membrane of Mycoplasma pneumoniae as a mixture of the two compounds. They are the major immunodeterminants of this pathogenic Mycoplasma and indicate high medicinal potential. They have a beta-(1-->6)-linked disaccharide structure close to each other; one has beta-d-galactopyranoside (beta-Gal-type 1) at the non-reducing terminal, and another has beta-d-glucopyranoside (beta-Glc-type 2).

One-pot alpha-glycosylation pathway via the generation in situ of alpha-glycopyranosyl imidates in N,N-dimethylformamide.

Divergent pathways are disclosed in the activation of 2-O-benzyl-1-hydroxy sugars by a reagent combination of CBr4 and Ph3P, all of which afford one-pot alpha-glycosylation methods. When this reagent is used in CH2Cl2, the 1-hydroxy sugar is converted to the alpha-glycosyl bromide in a conventional way and leads to the one-pot alpha-glycosylation method based on a halide ion-catalytic mechanism. In either DMF or a mixture of DMF and CHCl3, however, alternative alpha-glycosyl species are generated.