913060-79-4

Upstream product

• 932719-30-7 S-phenyl 2-O-benzyl-3,5-O-(di-tert-butylsilylene)-1-thio-α-L-arabinofuranoside S-oxide 
• 108-98-5 thiophenol 
• 85272-31-7 di-tert-butylsilyl bis(trifluoromethanesulfonate) 
• 913060-78-3 phenyl 3,5-O-(di-tert-butylsilanediyl)-1-thio-α-L-arabinofuranoside 
• 100-39-0 benzyl bromide 

Downstream Products

• 932719-32-9 S-phenyl 2-O-benzyl-3,5-O-(di-tert-butylsilylene)-1-thio-β-L-arabinofuranoside 
• 932719-30-7 S-phenyl 2-O-benzyl-3,5-O-(di-tert-butylsilylene)-1-thio-α-L-arabinofuranoside S-oxide 

Relevant academic research and scientific papers

On the use of 3,5-O-benzylidene and 3,5-O-(Di-tert-butylsilylene)-2-O- benzylarabinothiofuranosides and their sulfoxides as glycosyl donors for the synthesis of β-arabinofuranosides: Importance of the activation method

A 2-O-benzyl-3,5-O-benzylidene-α-D-thioarabinofuranoside was obtained by reaction of the corresponding diol with α,α-dibromotoluene under basic conditions. On activation with 1-benzenesulfinyl piperidine, or diphenyl sulfoxide, and trifluoromethanesulfonic anhydride in dichloromethane at -55 °C, reaction with glycosyl acceptors affords anomeric mixtures with little or no selectivity. The analogous 2-O-benzyl-3,5-O-(di-tert-butylsilylene)- α-D-thioarabinofuranoside also showed no significant selectivity under the 1-benzenesulfinyl piperidine or diphenyl sulfoxide conditions. With N-iodosuccinimide and silver trifluoromethanesulfonate the silylene acetal showed moderate to high β-selectivity, independent of the configuration of the starting thioglycoside. High β-selectivity was also obtained with a 2-O-benzyl-3,5-O-(di-tert-butylsilylene)-α-arabinofuranosyl sulfoxide donor on activation with trifluoromethanesulfonic anhydride. The high β-selectivities obtained by the N-iodosuccinimide/silver trifluoromethanesulfonate and sulfoxide methods are consistent with a common intermediate, most likely to be the oxacarbenium ion. The poor selectivity observed on activation of the thioglycosides with the 1-benzenesulfinyl piperidine, or diphenyl sulfoxide, and trifluoromethanesulfonic anhydride methods appears to be the result of the formation of a complex mixture of glycosyl donors, as determined by low-temperature NMR work.

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.