Deoxy-2- thiophenyl -glycosyl fluorides

Similarly, thioglycosides with a phenoxythiocarbonyl ester group at C-2 (109) undergo 1,2-migration of the anomeric phenyl- or ethylthio group when they are activated (110) by NIS/cat. TfOH. 

The intermediate episulfonium ion 111 is trapped by an alcohol to give P-D-glucopyranosides 112 when the starting compound is a phenyl- or ethylthio a-D- 

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Reactions with secondary acceptors proceeded in lower yields and exhibited sharply diminished stereoselectivities. It should be mentioned that 1,2-epoxides can be converted [43] to other glycosylating agents, thiophenyl glycoside 66, pentenyl glycoside 67, fluoride 68, which can be helpful after acylation at C-2 for the synthesis of 2-deoxy-P-glycosides (Scheme 15). 

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