Synthesis of 1,2--linked glycosides using dimethyl(methylthio) sulfonium triplate as promoter and thioglycosides as glycosyl donors

Metallocene bis(perfluoroalkanesulfonate)s as air-stable cationic Lewis acids

“…All the glycosylation products, glycosyl donors and acceptor 4 [18], 5a [19], 5b [18], 5c [20], 5d [21], 5e [22], 5f [23] and 5g [24], were characterized spectroscopically by comparison of 1 H and 13 C NMR spectral data reported.…”

Regenerative Glycosylation

“…This created the basis for discovering 3,3-difluoroxindole (HOFox)-mediated regenerative glycosylations wherein the OFox imidates were found to be key intermediates. 19 In our preliminary study we first reacted thioglycoside 1 20 with stoichiometric bromine to form glycosyl bromide 2 . The latter can be glycosidated slowly, but more readily gets converted into highly reactive OFox imidate 3 if HOFox is added.…”

General Aspects of the Glycosidic Bond Formation

“…Kinetically controlled glycosylations at lower temperatures generally favor 1,2-trans glycoside formation [100,120,[127][128][129][130], although converse observations have also been reported [131,132].…”

“…It has been unambiguously demonstrated that halides activated in the presence of a halide ion (from, e.g. Bu 4 NBr) often provide the highest ratios of a-/ b-glycosides [100][101][102][103][104]. Since in most cases the glycosylation reactions proceed via unimolecular S N 1 mechanism, the orientation of the leaving group at the anomeric center is of lesser importance.…”