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 [beta]-arabinofuranosides: Importance of the activation method

A 2-O-benzyl-3,5-O-benzylidene-[alpha]-D-thioarabinofuranoside which was obtained by reaction of the corresponding diol with [alpha],[alpha]-dibromotoluene under basic conditions is reviewed. 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.