In this study, we have designed, synthesized and full characterized a novel biological based acidic nano organocatalyst via condensations reaction of uric acid phosphorous acid. The obtained compound was named theacrine tetrakis(phosphonic acid) (TTPA) prepared under refluxing ethanol. This new applied as an efficient recyclable catalyst for the preparation pyridines with indole moieties cooper...

Solid-phase oligosaccharide synthesis offers the promise of providing libraries of oligosaccharides for glycomics research. A major stumbling block to solid-phase oligosaccharide synthesis has been a lack of general methods for the stereoselective installation of 1,2-cis-glycosides, and intractable mixtures of compounds are obtained if several such glycosides need to be installed. We have prepa...

A series of light-activatable perfluorophenylazide (PFPA)-conjugated carbohydrate structures have been synthesized and applied to glycoarray fabrication. The glycoconjugates were structurally varied with respect to anomeric attachment, S-, and O-linked carbohydrates, respectively, as well as linker structure and length. Efficient stereoselective synthetic routes were developed, leading to the f...

The stereochemistry of the ketosidic bond of sialic acid has been elucidated by a study of the two anomeric methyl ketosides. Isomer I was prepared by Koenig.+Knorr synthesis, and isomer II by direct methylation with methanol and an acid catalyst. These two anomeric configurations were established by conversion with periodate-borohydride to III and IV, respectively, followed by lactonization of...

In aqueous solution Dfructose 1,6-bisphosphate (FBP)? exists as equilibrium mixture of 20 + 4% a-D-fructofuranose 1,6-bisphosphate, 80 f 10% /3-Dfructofuranose 1,6-bisphosphate, and less than 1.5% of the open chain [l-4] . The two anomeric forms are spontaneously interconvertible via the open chain tautomer. The first order rate constant for the ring opening of the o!-D-fructofuranose 1,6-bisph...

Disaccharides tagged with p-aminobenzoic acid (ABA) were separated by capillary electrophoresis (CE) and analyzed on-line with negative ion electrospray ionization tandem mass spectrometry (ESI/MS/MS). The formation of glycosylamine instead of reductive amination was selected as the derivatization reaction. In negative ion ESI, the glycosylamine approach provides more information on linkage and...

A new and completely diastereoselective method for the introduction of fluorine into a noncarbohydrate sugar ring precursor has been developed. The use of N-fluorodibenzenesulfonimide (5) for the electrophilic fluorination of chiral lactone 4, which is derived from L-glutamic acid, yields the key intermediate 6. This is transformed into an anomeric acetate 8 and is used for the synthesis of a n...

Retaining glycosyltransferase enzymes retain the stereochemistry of the donor glycosidic linkage after transfer to an acceptor molecule. The mechanism these enzymes utilize to achieve retention of the anomeric stereochemistry has been a matter of much debate. Re-analysis of previously released structural data from retaining and inverting glycosyltransferases allows competing mechanistic proposa...

Spironucleosides are a type of conformationally restricted nucleoside analogs in which the anomeric carbon belongs simultaneously to the sugar moiety and to the base unit. This locks the nucleic base in a specific orientation around the N-glycosidic bond, imposing restrictions on the flexibility of the sugar moiety. Anomeric spiro-functionalized nucleosides have gained considerable importance w...