913060-93-2

Upstream product

• 913061-12-8 phenyl 4,6-O-benzylidene-3-O-(9-fluorenylmethoxycarbonyl)-1-thio-β-D-galactopyranoside 
• 100-44-7 benzyl chloride 
• 98-88-4 benzoyl chloride 
• 28920-43-6 (fluorenylmethoxy)carbonyl chloride 

Downstream Products

• 913060-96-5 3-azidopropyl 2-O-benzoyl-4,6-O-benzylidene-3-O-(9-fluorenylmethoxycarbonyl)-β-D-galactopyranosyl-(1->6)-2,3,4-tri-O-benzoyl-β-D-galactopyranoside 
• 913060-97-6 3-azidopropyl 2-O-benzoyl-4-O-benzyl-3-O-(9-fluorenylmethoxycarbonyl)-β-D-galactopyranosyl-(1->6)-2,3,4-tri-O-benzoyl-β-D-galactopyranoside 

Relevant academic research and scientific papers

Total Synthesis of the Repeating Unit of Bacteroides fragilis Zwitterionic Polysaccharide A1

Zwitterionic polysaccharides isolated from commensal bacteria are endowed with unique immunological properties and are emerging as immunotherapeutic agents as well as vaccine carriers. Reported herein is a total synthesis of the repeating unit of Bacteroides fragilis zwitterionic polysaccharide A1 (PS A1). The structurally complex tetrasaccharide unit contains a rare sugar 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose (AAT) and two consecutive 1,2-cis glycosidic linkages. The repeating unit was efficiently assembled by rapid synthesis of d-galactosamine and AAT building blocks from cheap and abundant d-mannose via a one-pot SN2 displacement of 2,4-bistriflates and installation of all of the glycosidic bonds in a highly stereoselective manner. The total synthesis involves a longest linear sequence of 17 steps with 3.47% overall yield.

Practical approach for the stereoselective introduction of β-arabinofuranosides

A practical approach for the stereoselective introduction of β-arabinofuranosides has been developed on the basis of locking an arabinosyl donor in a conformation in which nucleophilic attack from the β face is favored. The new glycosyl donor was designed by analyzing optimized geometries of low-energy conformers of the arabinofuranosyl oxacarbenium ion. The Newman projection of the E3 conformer indicated that nucleophilic attack from the α face is disfavored because an eclipsed H-2 will be encountered. On the other hand, an approach from the β face was expected to be more favorable, because it will experience only staggered substituents. The arabinofuranosyl oxacarbenium ion could be locked in the E3 conformation by employing a 3,5-O-di-tert-butylsilane protecting group, which places C-5 and O-3 in a pseudoequatorial orientation, resulting in a perfect chair conformation of the protecting group. The new glycosyl donor gave excellent β selectivities in a range of glycosylations with glycosyl acceptors having primary and secondary alcohols. The attractiveness of the new methodology was demonstrated by the chemical synthesis of a fragment of arabinogalactan, which is an important constituent of the primary plant cell wall.