Stereoselective α-Sialylation with Sialyl Pentenoates as Donors and PhSeOTf as the Activator

摘要

Sialic acids are a family of monosaccharides comprising about 40 members which have in common neuraminic acid (Neu) (5-amino-3,5-dideoxy-D-glycero-D-galacto-nonulosonic acid). Since the first discovery of N-acetylneuraminic acid (Neu5Ac, 1) from brain glycolipids or salivary mucins, many of sialic acids have been known to occur in animal and some microorganisms. Because they occupy the terminal position on macromolecules and cell membranes and thus are involved with essential functional roles in many biological and pathological phenomena, sialic acids have become a family of the most important molecules of life. The lead member of the family, Neu5Ac (1), which is found in important naturally occurring glycoconjugates and oligosaccharides, is typically linked to galactose through an α2→3 or an α2→6 linkage or is polymerized in the form of an α2→8 or an α2→9 linkage.