Glycosyl fluorides from n-pentenyl-related glycosyl donors — Application to glycosylation strategies

n-Pentenyl glycosides (NPGs) and n-pentenyl orthoesters (NPOEs) have been transformed into glycosyl fluorides by a variety of methods. In the case of NPGs, Barluenga’s reagent, bis(pyridinium)iodonium(I)tetrafluoroborate (IPy2BF4), gives good yields of glycosyl fluorides when HF–pyridine complex is used as an additional fluoride source. NPOEs can be activated either by a combination of electrophilic iodonium (Barluenga’s reagent) and HBF4 or by the action of HF–pyridine complex. The ensuing glycosyl fluorides form a semiorthogonal pair of glycosyl donors when confronted with NPGs.