Site-selective
acylations of α-and β-hydroxyamides
in complex polyols are described. The combination of a pyridine aldoxime
ester and Zn(OTf)2 facilitates the acylation of two types
of N-glycolyl disaccharides, namely, Gal-GlcNGc and
Neu5Gc-Gal, both of which are partial structures of polysaccharides
responsible for biological actions, with highly site-selective modifications
achieved. Furthermore, biotinylation, one of the most important techniques
in chemical biology, is used to site-selectively acylate the β-hydroxyl
group in a glycopeptide.