Thieme Chemistry Journals Awardees – Where Are They Now? ­Ribosylation of an Acid-Labile Glycosyl Acceptor as a Potential Key Step for the Synthesis of Nucleoside Antibiotics

Naturally occurring nucleoside antibiotics (e.g., muraymycins and caprazamycins) represent attractive lead structures for the development of urgently needed novel antibacterial agents. One major challenge in the total synthesis of muraymycins, caprazamycins, and their analogues is the efficient construction of the densely functionalized aminoribosylated uridine-derived core unit. In order to avoid tedious protecting-group manipulations, we have aimed to conduct the aminoribosylation step with an acid-labile glycosyl acceptor. Therefore, different glycosylation approaches have been studied, with pentenyl glycosides giving the best results.

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.