Glycoside bond formation in nature is essentially based on glycosyl donors having phosphates, pyrophosphates, or their ribonucleoside and lipid monoester derivatives as leaving groups, and glycosyltransferases as catalysts.[1–3] For instance, for aldoses and 3- deoxy-2-glyculosonates (Kdo, Neu5Ac), nucleoside diphosphate sugars and nucleoside monophosphate derivatives, respectively, are generally encountered as glycosyl donors ( ...