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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 11
BKCSDE 19(11)
November 20, 1998 

Transglycosylation of Permethylated Methyl D-Glycopyranosides in the Presence of Trimethylsilyl Trifluoromethanesulfonate
Chang Kiu Lee, Jung Ho Jun, Young Hwan Seo
Transglycosylation reactions among methyl 2,3,4,6-tetra-O-methyl-D-glycopyranosides and isomeric butyl alcohols or cyclohexanol took place in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) in dichloromethane. The extent of the reaction after 1 h and 24 h from mixing was determined by gas chromatography (GC). Anomerization of the substrate took place during the course of transglycosylation, which favors α anomer regardless of the anomeric configurations of the starting glycosides. Transglycosylation also favors the a anomer regardless of the steric bulkiness of the alcohol. tert-Butyl alcohol did not give any transglycosylation, suggesting the steric hindrance of approaching the bulky alcohol to the oxonium intermediate. A mechanism for the transglycosylation have been proposed.
1233 - 1238
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