Use of acyclic glycosyl donors for furanoside synthesis

摘要

Treatment of the peracetylated ethyl dithioacetals of D-glucose, D-galactose, and D-mannose with acetyl chloride and boron trifluoride diethyl etherate at reflux yields the known acyclic 1-chloro- 1-(ethylthio) derivatives. These compounds are shown to effectively glycosylate a variety of carbohydrate acceptors using silver trifluoromethanesulfonate as the promotor, affording stereospe- cifically the corresponding acyclic 0,S-acetals in good to excellent yield.